Chapter 3 SABIS Grade 10 Part 5 Practice
🔍 Lesson 14 🔍
🔍 Question 1: Decode the molecular formula "2 NH3" and explain the meaning of each letter and digit.
📝 Answer 1: The molecular formula "2 NH3" represents two separate molecules of ammonia (NH3). Each molecule consists of two elements: nitrogen (N) and hydrogen (H). The coefficient "2" indicates that there are two molecules of ammonia. Within each molecule, there is one atom of nitrogen and three atoms of hydrogen chemically bonded together.🔍
Question 2: Interpret the molecular formula "4 C6H12O6" and elaborate on the significance of each letter and digit.
📝 Answer 2: The molecular formula "4 C6H12O6" corresponds to four separate molecules of glucose. Each molecule of glucose contains atoms of carbon (C), hydrogen (H), and oxygen (O). The coefficient "4" indicates that there are four molecules of glucose. Within each molecule, there are six atoms of carbon, twelve atoms of hydrogen, and six atoms of oxygen chemically bonded together.
🔍 Question 3: Understand the meaning of the molecular formula "5 CO2" and provide an explanation for each symbol and number.
📝 Answer 3: The molecular formula "5 CO2" signifies five separate molecules of carbon dioxide (CO2). Each molecule consists of one atom of carbon (C) and two atoms of oxygen (O). The coefficient "5" denotes that there are five molecules of carbon dioxide. Within each molecule, there is one carbon atom and two oxygen atoms chemically bonded together.Fantastic job! Understanding the meaning of molecular formulas with coefficients allows us to determine the composition and arrangement of atoms within a compound. Keep up the great work! ✨😊
🔍 Question 4 : Translate the equation "3 CO2 + 4 H2O → C3H8O3" into words, describing the reaction in terms of molecules and atoms.
📝 Answer 4 : Three molecules of carbon dioxide react with four molecules of water to produce one molecule of C3H8O3. Alternatively, three moles of carbon dioxide react with four moles of water to yield one mole of C3H8O3.
🔍 Question 5 : Interpret the equation "2 Al + 3 Br2 → 2 AlBr3" in words, explaining the reaction in terms of molecules and atoms.
📝 Answer 5 : Two molecules of aluminum react with three molecules of bromine to form two molecules of aluminum bromide. In terms of atoms, two moles of aluminum react with three moles of bromine to produce two moles of aluminum bromide.
🔍 Question 6 : Elaborate on the equation "N2 + 3 H2 → 2 NH3" in words, describing the reaction in terms of molecules and atoms.
📝 Answer 6: One molecule of nitrogen reacts with three molecules of hydrogen to give two molecules of ammonia. Alternatively, one mole of nitrogen reacts with three moles of hydrogen to yield two moles of ammonia.
🔍 Question 7 : 🤔 Determine the atomicity of the following substances:
Ne NO HCl NH3 CH4 CO2
📝 Answer: ✅ Here's the atomicity of each substance:
Ne: Atomicity of 1. Neon exists as single atoms. 💫
NO: Atomicity of 2. Nitric oxide consists of two atoms bonded together. 🔀
HCl: Atomicity of 2. Hydrochloric acid is composed of two atoms, one each of hydrogen and chlorine, chemically bonded. ⚗️
NH3: Atomicity of 4. Ammonia consists of four atoms, one nitrogen and three hydrogen atoms, chemically bonded together. 🌾
CH4: Atomicity of 5. Methane comprises five atoms, one carbon and four hydrogen atoms, chemically bonded together. 🔥
CO2: Atomicity of 3. Carbon dioxide consists of three atoms, one carbon and two oxygen atoms, chemically bonded together. ☁️
Understanding the atomicity of substances helps us comprehend the arrangement and composition of atoms within a molecule. Well done! 🎉👍
🔍 Question 8: 💡 Find the simplest formula for each of the following substances:
a) Benzene: C6H6 b) Ethane: C2H6 c) Sodium nitrate: NaNO3 d) Sand: SiO2 e) Vinegar: CH3COOH f) Fructose: C6H12O6
📝 Answer: ✅ Here are the simplest formulas for each substance:
a) Benzene: CH. The simplest formula of benzene represents one carbon atom and one hydrogen atom in each repeating unit of the molecule. 🌺 b) Ethane: CH3. The simplest formula of ethane consists of one carbon atom bonded to three hydrogen atoms. 🚀 c) Sodium nitrate: NaNO3. The given formula already represents the simplest ratio of atoms in sodium nitrate. 🔩 d) Sand: SiO2. The simplest formula of sand indicates that each silicon atom is bonded to two oxygen atoms. 🏖️ e) Vinegar: CH2O. The simplest formula of vinegar reveals one carbon atom, two hydrogen atoms, and one oxygen atom in each molecule. 🍷 f) Fructose: CH2O. The simplest formula of fructose displays one carbon atom, two hydrogen atoms, and one oxygen atom per molecule. 🍏
Knowing the simplest formulas helps us understand the fundamental composition of substances. Great job! 🎉👍 🔍 Question 9: 💡 Name or write the formula for the following binary compounds:
I. Write the formula of:
a) Sulphur dioxide: SO2
b) Phosphorus pentachloride: PCl5 c) Dinitrogen pentoxide: N2O5
II. Give the name of: a) HI: Hydrogen iodide b) CCl4: Carbon tetrachloride c) NO2: Nitrogen dioxide
📝 Answer: ✅ Here are the formulas and names of the given binary compounds:
I. Write the formula of: a) Sulphur dioxide: SO2 b) Phosphorus pentachloride: PCl5 c) Dinitrogen pentoxide: N2O5
II. Give the name of: a) HI: Hydrogen iodide b) CCl4: Carbon tetrachloride c) NO2: Nitrogen dioxide
Understanding how to name and write the formulas of binary compounds is crucial for communicating and identifying different substances. Well done! 🎉👍 🔍 Question 10: 💡 Name or write the formula for the following binary compounds:
I. Write the formula of: a) Potassium oxide b) Aluminum chloride c) Carbon monoxide
II. Give the name of: a) SO3 b) MgBr2 c) H2S
📝 Answer: ✅ Here are the formulas and names of the additional binary compounds:
I. Write the formula of: a) Potassium oxide: K2O b) Aluminum chloride: AlCl3 c) Carbon monoxide: CO
II. Give the name of: a) SO3: Sulfur trioxide b) MgBr2: Magnesium bromide c) H2S: Hydrogen sulfide
Great job! Naming and writing formulas for binary compounds is an essential skill in chemistry. Keep up the excellent work! 🎉👍
Here's a brief explanation of the questions 11-14 concept:
In chemistry, we often use a unit called atomic mass unit (amu) to measure the mass of atoms. Atomic mass unit is a way to express the relative mass of an atom compared to a reference atom, which is carbon-12 (C-12). The atomic mass unit is defined as 1/12th of the mass of a carbon-12 atom.
Knowing the mass of atoms in amu is important because it helps us understand the composition of different elements and compounds. In the following questions (11-14), we will explore the mass of specific atoms and determine their mass in atomic mass units (amu).
🔍 Question 11: 💡 Determine the mass in atomic mass units (amu) for the following atoms:
a) What is the mass of an atom of silver in amu? (Answer: 108 amu)
📝 Answer 11: ✅ The mass of an atom of silver is 108 amu.
🔍 Question 12: 💡 Find the mass in amu for the following atoms:
a) What is the mass of an atom of oxygen in amu? b) Determine the mass of a carbon atom in amu. c) Calculate the mass of a helium atom in amu.
📝 Answer 12: a) The mass of an atom of oxygen is approximately 16 amu. b) A carbon atom has a mass of about 12 amu. c) The mass of a helium atom is around 4 amu.
🔍 Question 13: 💡 Identify the mass in amu for the given atoms:
a) What is the mass of an atom of hydrogen in amu? b) Determine the mass of a nitrogen atom in amu. c) Calculate the mass of a sulfur atom in amu.
📝 Answer 13: a) An atom of hydrogen has a mass of approximately 1 amu. b) The mass of a nitrogen atom is about 14 amu. c) A sulfur atom has a mass of around 32 amu.
🔍 Question 14: 💡 Find the mass in atomic mass units (amu) for the following atoms:
a) What is the mass of an atom of gold in amu? b) Determine the mass of a chlorine atom in amu. c) Calculate the mass of a lithium atom in amu.
📝 Answer 14: a) The mass of an atom of gold is approximately 197 amu. b) A chlorine atom has a mass of about 35.5 amu. c) The mass of a lithium atom is around 7 amu.
Well done! Understanding the mass of atoms in atomic mass units (amu) is essential in chemistry. Keep up the great work! 🎉👍
Here's a brief explanation of the questions 15-18 concept:
Concept Explanation: In chemistry, we often work with large quantities of atoms. Avogadro's number, which is approximately 6.02 × 10^23, represents the number of atoms or molecules present in one mole of a substance. It allows us to relate the number of particles to the mass of a substance.
Knowing the mass of a specific number of atoms is important as it helps us understand the total mass of a given element or compound. By using the atomic mass of an element, we can calculate the mass of a specified number of atoms.
🔍 Question 15: What is the mass of 6.02 × 10^23 atoms of oxygen in grams? (Atomic mass of oxygen = 16 g/mol)
📝 Answer 15: The mass of 6.02 × 10^23 atoms of oxygen is equal to the atomic mass of oxygen, which is 16 grams per mole. Therefore, the mass of 6.02 × 10^23 atoms of oxygen is also 16 grams.
🔍 Question 16: Calculate the mass of 6.02 × 10^23 atoms of carbon in grams. (Atomic mass of carbon = 12 g/mol)
📝 Answer 16: The mass of 6.02 × 10^23 atoms of carbon can be determined using the atomic mass of carbon, which is 12 grams per mole. Therefore, the mass of 6.02 × 10^23 atoms of carbon is also 12 grams.
🔍 Question 17: Determine the mass of 6.02 × 10^23 atoms of hydrogen in grams. (Atomic mass of hydrogen = 1 g/mol)
📝 Answer 17: The mass of 6.02 × 10^23 atoms of hydrogen can be calculated using the atomic mass of hydrogen, which is 1 gram per mole. Therefore, the mass of 6.02 × 10^23 atoms of hydrogen is also 1 gram.
🔍 Question 18: Find the mass of 6.02 × 10^23 atoms of nitrogen in grams. (Atomic mass of nitrogen = 14 g/mol)
📝 Answer 18: The mass of 6.02 × 10^23 atoms of nitrogen is determined by the atomic mass of nitrogen, which is 14 grams per mole. Therefore, the mass of 6.02 × 10^23 atoms of nitrogen is also 14 grams.
Concept Explanation: The concept of molar mass is crucial in chemistry as it allows us to determine the mass of one mole of a substance. Molar mass is expressed in grams per mole (g/mol) and represents the mass of the element or compound in atomic mass units (amu) when scaled up to one mole.
🔍 Question 19: Calculate the mass of 1 mole of oxygen in grams. (Atomic mass of oxygen = 16 g/mol)
📝 Answer 19: The mass of 1 mole of oxygen is equal to its molar mass, which is 16 grams per mole. Therefore, the mass of 1 mole of oxygen is 16 grams.
🔍 Question 20: Find the mass of 1 mole of carbon in grams. (Atomic mass of carbon = 12 g/mol)
📝 Answer 20: The mass of 1 mole of carbon is determined by its molar mass, which is 12 grams per mole. Hence, the mass of 1 mole of carbon is 12 grams.
🔍 Question 21: Determine the mass of 1 mole of hydrogen in grams. (Atomic mass of hydrogen = 1 g/mol)
📝 Answer 21: The mass of 1 mole of hydrogen is calculated using its molar mass, which is 1 gram per mole. Consequently, the mass of 1 mole of hydrogen is 1 gram.
🔍 Question 22: Calculate the mass of 1 mole of nitrogen in grams. (Atomic mass of nitrogen = 14 g/mol)
📝 Answer 22: The mass of 1 mole of nitrogen can be found using its molar mass, which is 14 grams per mole. Therefore, the mass of 1 mole of nitrogen is 14 grams.
Concept Explanation: When given the mass of a substance, we can determine the number of moles and the number of atoms present. This involves using the molar mass of the substance and Avogadro's number.
To find the number of moles, we divide the given mass by the molar mass of the substance. The molar mass represents the mass of one mole of the substance in grams.
To find the number of atoms, we multiply the number of moles by Avogadro's number and the atomicity of the substance. The atomicity refers to the number of atoms in one molecule of the substance.
🔍 Question 23: Calculate the number of moles and the number of atoms in 8.2 g of carbon dioxide (CO2). Given: mCO2 = 8.2 g, atomicity of CO2 = 3.
📝 Answer 23: To find the number of moles of CO2, we divide the given mass by its molar mass. The molar mass of CO2 is approximately 44 g/mol.
nCO2 = mCO2 / MCO2 = 8.2 g / 44 g/mol ≈ 0.186 moles
To find the number of atoms, we multiply the number of moles by Avogadro's number (6.02 × 10^23) and the atomicity of CO2 (3).
Number of atoms = nCO2 × (6.02 × 10^23) × atomicity = 0.186 × (6.02 × 10^23) × 3 ≈ 3.37 × 10^23 atoms
🔍 Question 24: Determine the number of moles and the number of atoms in 25 g of water (H2O). Given: mH2O = 25 g, atomicity of H2O = 3.
📝 Answer 24: The molar mass of water (H2O) is approximately 18 g/mol. To find the number of moles:
nH2O = mH2O / MH2O = 25 g / 18 g/mol ≈ 1.39 moles
To find the number of atoms, we multiply the number of moles by Avogadro's number (6.02 × 10^23) and the atomicity of H2O (3).
Number of atoms = nH2O × (6.02 × 10^23) × atomicity = 1.39 × (6.02 × 10^23) × 3 ≈ 2.51 × 10^24 atoms
🔍 Question 25: Calculate the number of moles and the number of atoms in 15 g of methane (CH4). Given: mCH4 = 15 g, atomicity of CH4 = 5.
📝 Answer 25: The molar mass of methane (CH4) is approximately 16 g/mol. To find the number of moles:
nCH4 = mCH4 / MCH4 = 15 g / 16 g/mol ≈ 0.938 moles
To find the number of atoms, we multiply the number of moles by Avogadro's number (6.02 × 10^23) and the atomicity of CH4 (5).
Number of atoms = nCH4 × (6.02 × 10^23) × atomicity = 0.938 × (6.02 × 10^23) × 5 ≈ 2.83 × 10^24 atoms
Concept Explanation: When given the mass of a substance, we can calculate the number of moles, molecules, and atoms present. This involves using the molar mass of the substance and Avogadro's number.
To find the number of moles, we divide the given mass by the molar mass of the substance. The molar mass represents the mass of one mole of the substance in grams.
To calculate the number of molecules, we multiply the number of moles by Avogadro's number (6.02 × 10^23). This gives us the number of molecules present in the given mass.
To determine the number of atoms, we multiply the number of molecules by the atomicity of the substance. The atomicity refers to the number of atoms in one molecule of the substance.
🔍 Question 26: Calculate the number of moles, molecules, and atoms in 3.50 g of hydrogen (H2). Given: mH2 = 3.50 g.
📝 Answer 26: To find the number of moles of hydrogen, we divide the given mass by its molar mass. The molar mass of hydrogen is approximately 2 g/mol.
nH2 = mH2 / MH2 = 3.50 g / 2 g/mol = 1.75 moles
To calculate the number of molecules, we multiply the number of moles by Avogadro's number (6.02 × 10^23).
Number of molecules = nH2 × (6.02 × 10^23) = 1.75 × (6.02 × 10^23) = 1.05 × 10^24 molecules
To determine the number of atoms, we multiply the number of molecules by the atomicity of hydrogen (2).
Number of atoms = number of molecules × atomicity = 1.05 × 10^24 × 2 = 2.10 × 10^24 atoms
🔍 Question 27: Find the number of moles, molecules, and atoms in 5.60 g of carbon dioxide (CO2). Given: mCO2 = 5.60 g.
📝 Answer 27: The molar mass of carbon dioxide (CO2) is approximately 44 g/mol. To find the number of moles:
nCO2 = mCO2 / MCO2 = 5.60 g / 44 g/mol = 0.127 moles
To calculate the number of molecules, we multiply the number of moles by Avogadro's number (6.02 × 10^23).
Number of molecules = nCO2 × (6.02 × 10^23) = 0.127 × (6.02 × 10^23) = 7.65 × 10^22 molecules
To determine the number of atoms, we multiply the number of molecules by the atomicity of CO2 (3).
Number of atoms = number of molecules × atomicity = 7.65 × 10^22 × 3 = 2.30 × 10^23 atoms
🔍 Question 28: Calculate the number of moles, molecules, and atoms in 4.80 g of water (H2O). Given: mH2O = 4.80 g.
📝 Answer 28: The molar mass of water (H2O) is approximately 18 g/mol. To find the number of moles:
nH2O = mH2O / MH2O = 4.80 g / 18 g/mol = 0.267 moles
To calculate the number of molecules, we multiply the number of moles by Avogadro's number (6.02 × 10^23).
Number of molecules = nH2O × (6.02 × 10^23) = 0.267 × (6.02 × 10^23) = 1.61 × 10^23 molecules
To determine the number of atoms, we multiply the number of molecules by the atomicity of water (3).
Number of atoms = number of molecules × atomicity = 1.61 × 10^23 × 3 = 4.83 × 10^23 atoms
Concept Explanation: We can calculate the number of moles and the mass of a given number of molecules of a substance. This involves using Avogadro's number and the molar mass of the substance.
To find the number of moles, we divide the given number of molecules by Avogadro's number (6.02 × 10^23). This gives us the quantity in moles.
To calculate the mass, we multiply the number of moles by the molar mass of the substance. The molar mass represents the mass of one mole of the substance in grams.
🔍 Question 29: How many moles do 1.20 × 10^23 molecules of carbon dioxide (CO2) represent? Calculate the mass of the given quantity. Given: 1.20 × 10^23 molecules of CO2.
📝 Answer 29: To find the number of moles, we divide the given number of molecules by Avogadro's number.
Number of moles = (1.20 × 10^23) / (6.02 × 10^23) = 0.199 moles
To calculate the mass, we multiply the number of moles by the molar mass of carbon dioxide (CO2).
Mass = number of moles × molar mass = 0.199 moles × (12 + 16 + 16) g/mol = 15.9 g
🔍 Question 30: Determine the number of moles represented by 4.50 × 10^24 molecules of water (H2O). Calculate the mass of the given quantity. Given: 4.50 × 10^24 molecules of H2O.
📝 Answer 30: To find the number of moles, we divide the given number of molecules by Avogadro's number.
Number of moles = (4.50 × 10^24) / (6.02 × 10^23) = 7.48 moles
To calculate the mass, we multiply the number of moles by the molar mass of water (H2O).
Mass = number of moles × molar mass = 7.48 moles × (2 + 16) g/mol = 179 g
🔍 Question 31: Find the number of moles represented by 2.75 × 10^22 molecules of methane (CH4). Calculate the mass of the given quantity. Given: 2.75 × 10^22 molecules of CH4.
📝 Answer 31: To find the number of moles, we divide the given number of molecules by Avogadro's number.
Number of moles = (2.75 × 10^22) / (6.02 × 10^23) = 0.0456 moles
To calculate the mass, we multiply the number of moles by the molar mass of methane (CH4).
Mass = number of moles × molar mass = 0.0456 moles × (12 + 4) g/mol = 2.51 g
Concept Explanation: We can calculate the number of molecules and atoms in a given number of moles of a substance. This involves using Avogadro's number and the concept of atomicity.
To find the number of molecules, we multiply the number of moles by Avogadro's number (6.02 × 10^23). This gives us the quantity in molecules.
To calculate the number of atoms, we multiply the number of molecules by the atomicity, which represents the number of atoms in one molecule of the substance.
🔍 Question 32: Calculate the number of molecules and atoms in 2.5 moles of CO2 (carbon dioxide). Given: 2.5 moles of CO2.
📝 Answer 32: To find the number of molecules, we multiply the number of moles by Avogadro's number.
Number of molecules = 2.5 moles × 6.02 × 10^23 molecules/mole = 1.51 × 10^24 molecules
To calculate the number of atoms, we multiply the number of molecules by the atomicity of CO2, which is 3 (1 carbon atom and 2 oxygen atoms per molecule).
Number of atoms = 1.51 × 10^24 molecules × 3 atoms/molecule = 4.53 × 10^24 atoms
🔍 Question 33: Find the number of molecules and atoms in 0.75 moles of H2O (water). Given: 0.75 moles of H2O.
📝 Answer 33: To find the number of molecules, we multiply the number of moles by Avogadro's number.
Number of molecules = 0.75 moles × 6.02 × 10^23 molecules/mole = 4.52 × 10^23 molecules
To calculate the number of atoms, we multiply the number of molecules by the atomicity of H2O, which is 3 (2 hydrogen atoms and 1 oxygen atom per molecule).
Number of atoms = 4.52 × 10^23 molecules × 3 atoms/molecule = 1.36 × 10^24 atoms
🔍 Question 34: Determine the number of molecules and atoms in 1.2 moles of O2 (oxygen gas). Given: 1.2 moles of O2.
📝 Answer 34: To find the number of molecules, we multiply the number of moles by Avogadro's number.
Number of molecules = 1.2 moles × 6.02 × 10^23 molecules/mole = 7.22 × 10^23 molecules
To calculate the number of atoms, we multiply the number of molecules by the atomicity of O2, which is 2 (2 oxygen atoms per molecule).
Number of atoms = 7.22 × 10^23 molecules × 2 atoms/molecule = 1.44 × 10^24 atoms
Well done! Understanding the relationship between moles, molecules, and atoms helps us quantify and comprehend the vastness of the microscopic world. Keep up the fantastic work! 🎉👏
Concept Explanation: We can determine the number of moles and the number of molecules in a given volume of a substance at STP (Standard Temperature and Pressure). This involves using the volume of the substance and the conversion factor of 22.4 liters per mole at STP.
To find the number of moles, we divide the given volume by the molar volume at STP (22.4 liters/mol). This gives us the quantity in moles.
To calculate the number of molecules, we multiply the number of moles by Avogadro's number (6.02 × 10^23 molecules/mol). This gives us the quantity in molecules.
🔍 Question 35: Calculate the number of moles and the number of molecules in 840 cm³ of oxygen gas (O₂) at STP. Given: V of O₂ = 840 cm³ at STP.
📝 Answer 35: To find the number of moles, we convert the given volume to liters by dividing it by 1000 (since 1 liter = 1000 cm³), and then divide by the molar volume at STP.
V = 840 cm³ = 0.840 liters
Number of moles = V / molar volume at STP = 0.840 L / 22.4 L/mol = 0.0375 moles
To calculate the number of molecules, we multiply the number of moles by Avogadro's number.
Number of molecules = 0.0375 moles × 6.02 × 10^23 molecules/mol = 2.26 × 10^22 molecules
🔍 Question 36: Determine the number of moles and the number of molecules in 5.60 liters of hydrogen gas (H₂) at STP. Given: V of H₂ = 5.60 liters at STP.
📝 Answer 36: To find the number of moles, we divide the given volume by the molar volume at STP.
Number of moles = V / molar volume at STP = 5.60 L / 22.4 L/mol = 0.250 moles
To calculate the number of molecules, we multiply the number of moles by Avogadro's number.
Number of molecules = 0.250 moles × 6.02 × 10^23 molecules/mol = 1.51 × 10^23 molecules
🔍 Question 37: Find the number of moles and the number of molecules in 4.50 dm³ of nitrogen gas (N₂) at STP. Given: V of N₂ = 4.50 dm³ at STP.
📝 Answer 37: To find the number of moles, we divide the given volume by the molar volume at STP.
Number of moles = V / molar volume at STP = 4.50 dm³ / 22.4 dm³/mol = 0.201 moles
To calculate the number of molecules, we multiply the number of moles by Avogadro's number.
Number of molecules = 0.201 moles × 6.02 × 10^23 molecules/mol = 1.21 × 10^23 molecules
Great job! Understanding the relationship between volume, moles, and molecules at STP helps us relate macroscopic measurements to the microscopic world of atoms and molecules. Keep up the excellent work! 🎉👍 Concept Explanation: When comparing the number of atoms in given masses of two elements, we need to calculate the number of moles for each element using their respective masses and molar masses. Then, we can determine which element has a higher number of atoms by comparing the number of moles.To find the number of moles, we divide the given mass by the molar mass of each element. The molar mass represents the mass of one mole of a substance.Once we have the number of moles for each element, we can compare them. The element with a higher number of moles will have more atoms.🔍 Question 38: Compare the number of atoms in 5.0 grams of oxygen (O) and 8.0 grams of sulfur (S). Given: mO = 5.0 g and mS = 8.0 g.📝 Answer 38: To determine the number of atoms, we first calculate the number of moles for each element.nO = mO / MO = 5.0 g / 16.0 g/mol = 0.3125 moles nS = mS / MS = 8.0 g / 32.0 g/mol = 0.25 molesSince nO > nS, 5.0 grams of oxygen has more atoms than 8.0 grams of sulfur.IF THE QUESTION REQUIRES FINDING THE NUMBER OF ATOMS OF EACH ELEMENT:nO = mO / MO = 5.0 g / 16.0 g/mol = 0.3125 moles nS = mS / MS = 8.0 g / 32.0 g/mol = 0.25 molesNumber of oxygen atoms = nO × NA = 0.3125 moles × 6.02 × 10^23 atoms/mol = 1.88 × 10^23 atoms Number of sulfur atoms = nS × NA = 0.25 moles × 6.02 × 10^23 atoms/mol = 1.51 × 10^23 atomsTherefore, 5.0 grams of oxygen has more atoms than 8.0 grams of sulfur.🔍 Question 39: Which has more atoms, 10.0 grams of carbon (C) or 15.0 grams of nitrogen (N)? Given: mC = 10.0 g and mN = 15.0 g.📝 Answer 39: To find the number of atoms, we calculate the number of moles for each element.nC = mC / MC = 10.0 g / 12.0 g/mol = 0.833 moles nN = mN / MN = 15.0 g / 14.0 g/mol = 1.07 molesSince nN > nC, 15.0 grams of nitrogen has more atoms than 10.0 grams of carbon.IF THE QUESTION REQUIRES FINDING THE NUMBER OF ATOMS OF EACH ELEMENT:nC = mC / MC = 10.0 g / 12.0 g/mol = 0.833 moles nN = mN / MN = 15.0 g / 14.0 g/mol = 1.07 molesNumber of carbon atoms = nC × NA = 0.833 moles × 6.02 × 10^23 atoms/mol = 5.01 × 10^23 atoms Number of nitrogen atoms = nN × NA = 1.07 moles × 6.02 × 10^23 atoms/mol = 6.44 × 10^23 atomsHence, 15.0 grams of nitrogen has more atoms than 10.0 grams of carbon.🔍 Question 40: Compare the number of atoms in 3.5 grams of hydrogen (H) and 2.0 grams of chlorine (Cl). Given: mH = 3.5 g and mCl = 2.0 g.📝 Answer 40: To determine the number of atoms, we first calculate the number of moles for each element.nH = mH / MH = 3.5 g / 1.0 g/mol = 3.5 moles nCl = mCl / MCl = 2.0 g / 35.5 g/mol = 0.0563 molesSince nH > nCl, 3.5 grams of hydrogen has more atoms than 2.0 grams of chlorine.IF THE QUESTION REQUIRES FINDING THE NUMBER OF ATOMS OF EACH ELEMENT:nH = mH / MH = 3.5 g / 1.0 g/mol = 3.5 moles nCl = mCl / MCl = 2.0 g / 35.5 g/mol = 0.0563 molesNumber of hydrogen atoms = nH × NA = 3.5 moles × 6.02 × 10^23 atoms/mol = 2.11 × 10^24 atoms Number of chlorine atoms = nCl × NA = 0.0563 moles × 6.02 × 10^23 atoms/mol = 3.39 × 10^22 atomsTherefore, 3.5 grams of hydrogen has more atoms than 2.0 grams of chlorine.Great job! Understanding the relationship between mass, moles, and the number of atoms helps us compare quantities of different elements and their atomic compositions. Keep up the fantastic work! 🎉👍
Concept Explanation: To find the molecular formula of a compound given its molar mass and simplest formula, we need to determine the value of "n" in the molecular formula (CH)n. "n" represents the number of empirical formula units present in one molecule of the compound.
The molar mass of the compound can be calculated by multiplying the molar mass of the empirical formula by "n". By equating this molar mass to the given molar mass, we can solve for "n".
Once we have determined the value of "n", we can write the molecular formula of the compound by multiplying the empirical formula by "n".
🔍 Question 41: A compound has a molar mass of 108 g/mol. If its simplest formula is NH2, determine its molecular formula.
📝 Answer 41: Given: Simplest formula = NH2, Molar mass = 108 g/mol
To find the molecular formula, we need to determine the value of "n" in the molecular formula (NH2)n.
Molar mass = empirical formula mass × n
108 g/mol = (14 + 2) g/mol × n 108 g/mol = 16 g/mol × n
n = 108 g/mol / 16 g/mol n = 6.75
Since "n" should be an integer, we round it to the nearest whole number, which is 7.
The molecular formula of the compound is (NH2)7.
IF THE QUESTION REQUIRES FINDING THE MOLECULAR FORMULA OF ANOTHER COMPOUND:
Follow the same procedure by substituting the given simplest formula and molar mass into the calculations.
🔍 Question 42: A compound has a molar mass of 180 g/mol. If its simplest formula is C2H4O, what is its molecular formula?
📝 Answer 42: Given: Simplest formula = C2H4O, Molar mass = 180 g/mol
To find the molecular formula, we need to determine the value of "n" in the molecular formula (C2H4O)n.
Molar mass = empirical formula mass × n
180 g/mol = (12 + 4 + 16) g/mol × n 180 g/mol = 32 g/mol × n
n = 180 g/mol / 32 g/mol n = 5.625
Since "n" should be an integer, we round it to the nearest whole number, which is 6.
The molecular formula of the compound is (C2H4O)6.
Great work! Finding the molecular formula based on the molar mass and simplest formula allows us to determine the actual composition of a compound. Keep up the excellent progress! 🎉👍
Concept Explanation: To find the molar mass of a compound given its simplest formula and the number of carbon atoms per molecule, we need to determine the molecular formula of the compound first. The molecular formula represents the actual number and types of atoms in one molecule of the compound.
In this case, the simplest formula is CClH2, and we know that there are two carbon atoms in one molecule of the compound. Therefore, the molecular formula will be (CClH2)2.
To calculate the molar mass, we need to sum up the atomic masses of all the atoms in the molecular formula. Each element's atomic mass can be found on the periodic table.
🔍 Question 43: A compound has a simplest formula of NH3 with 3 nitrogen atoms per molecule. Determine its molar mass.
📝 Answer 43: Given: Simplest formula = NH3 with 3 nitrogen atoms per molecule
To find the molecular formula, we write it as (NH3)3.
To calculate the molar mass, we sum up the atomic masses of all the atoms in the molecular formula.
Molar mass = (14 × 3) + (1 × 9) = 42 + 9 = 51 g/mol
The molar mass of the compound is 51 g/mol.
IF THE QUESTION REQUIRES FINDING THE MOLECULAR FORMULA WITH A DIFFERENT NUMBER OF CARBON ATOMS:
Follow the same procedure by substituting the given simplest formula and the number of carbon atoms per molecule into the calculations.
🔍 Question 44: A compound has a simplest formula of C2H4O with 4 carbon atoms per molecule. What is its molar mass?
📝 Answer 44: Given: Simplest formula = C2H4O with 4 carbon atoms per molecule
To find the molecular formula, we write it as (C2H4O)4.
To calculate the molar mass, we sum up the atomic masses of all the atoms in the molecular formula.
Molar mass = (12 × 2 × 4) + (1 × 4 × 4) + (16 × 4) = 96 + 16 + 64 = 176 g/mol
The molar mass of the compound is 176 g/mol.
Fantastic job! Determining the molecular formula and molar mass of a compound provides crucial information about its composition. Keep up the excellent progress! 🎉👍
Concept Explanation: To find the mass of a specific element in a compound, we need to consider the compound's molar mass and the mole ratio between the element and the compound.
In this case, we are given the mass of ethanol, which is C2H5OH, and we need to determine the mass of carbon (C) in the compound.
First, we calculate the number of moles of ethanol using the formula: n = m/M, where m is the given mass of ethanol and M is the molar mass of ethanol.
Next, we determine the mole ratio of carbon in ethanol. Since there are 2 moles of carbon in 1 mole of ethanol, we multiply the number of moles of ethanol by the mole ratio to obtain the number of moles of carbon.
Finally, we calculate the mass of carbon by multiplying the number of moles of carbon by the atomic mass of carbon.
🔍 Question 45: Find the mass of nitrogen present in 2.5 g of ammonium nitrate, NH4NO3. Given: mass of ammonium nitrate = 2.5 g R.T.F: mass of N = ?
n = m/M = 2.5/80 = 0.03125 moles 1 mole of ammonium nitrate contains 1 mole of nitrogen n of N = 0.03125 moles m of N = n × M = 0.03125 × 14 = 0.4375 g
🔍 Question 46: Calculate the mass of oxygen present in 5.6 g of calcium carbonate, CaCO3. Given: mass of calcium carbonate = 5.6 g R.T.F: mass of O = ?
n = m/M = 5.6/100 = 0.056 moles 1 mole of calcium carbonate contains 3 moles of oxygen n of O = 0.056 × 3 = 0.168 moles m of O = n × M = 0.168 × 16 = 2.688 g
🔍 Question 47: Determine the mass of hydrogen present in 1.8 g of water, H2O. Given: mass of water = 1.8 g R.T.F: mass of H = ?
n = m/M = 1.8/18 = 0.1 moles 1 mole of water contains 2 moles of hydrogen n of H = 0.1 × 2 = 0.2 moles m of H = n × M = 0.2 × 1 = 0.2 g
Concept Explanation: According to Avogadro's hypothesis, at the same temperature and pressure, equal volumes of different gases contain the same number of particles. Therefore, the ratio of the molecular masses of two gases can be determined by comparing the masses of equal volumes of the gases.
In this case, we are given the masses of 1 dm3 of gas S and gas T, and we need to find the ratio of their molecular masses.
To calculate the ratio, we divide the molecular mass of gas S by the mass of 1 dm3 of gas S, and then divide the molecular mass of gas T by the mass of 1 dm3 of gas T.
🔍 Question 48: At the same conditions of temperature and pressure, 1 dm3 of gas A has a mass of 2.0 g, while 1 dm3 of gas B has a mass of 3.5 g. Determine the ratio of the molecular masses of the two gases.
Given: m of 1 dm3 of gas A = 2.0 g, m of 1 dm3 of gas B = 3.5 g R.T.F: Ratio of the molecular masses
Molecular mass of gas A / mass of 1 dm3 of gas A = Molecular mass of gas B / mass of 1 dm3 of gas B Molecular mass of gas A = (2.0 g) x (Molecular mass of gas B) / (3.5 g)
🔍 Question 49: Under the same temperature and pressure, 1 dm3 of gas X has a mass of 1.8 g, while 1 dm3 of gas Y has a mass of 2.5 g. Find the ratio of the molecular masses of gas X and gas Y.
Given: m of 1 dm3 of gas X = 1.8 g, m of 1 dm3 of gas Y = 2.5 g R.T.F: Ratio of the molecular masses
Molecular mass of gas X / mass of 1 dm3 of gas X = Molecular mass of gas Y / mass of 1 dm3 of gas Y Molecular mass of gas X = (1.8 g) x (Molecular mass of gas Y) / (2.5 g)
🔍 Question 50: At the same temperature and pressure, 1 dm3 of gas P has a mass of 0.9 g, while 1 dm3 of gas Q has a mass of 1.2 g. Calculate the ratio of the molecular masses of gas P and gas Q.
Given: m of 1 dm3 of gas P = 0.9 g, m of 1 dm3 of gas Q = 1.2 g R.T.F: Ratio of the molecular masses
Molecular mass of gas P / mass of 1 dm3 of gas P = Molecular mass of gas Q / mass of 1 dm3 of gas Q Molecular mass of gas P = (0.9 g) x (Molecular mass of gas Q) / (1.2 g)
Concept Explanation: When comparing the masses of different volumes of gases at the same temperature and pressure, we can determine the molar mass of one gas when the molecular formula and mass of another gas are given. This is based on the idea that equal volumes of gases at the same conditions contain an equal number of particles.In this case, we are given the mass of 5.0 dm3 of gas with the molecular formula C2H2 and the mass of 1.0 dm3 of gas D. We need to find the molar mass of gas D.To find the molar mass of gas D, we first calculate the mass of 5.0 dm3 of gas D by multiplying the mass of 1.0 dm3 by 5. Then, we can calculate the molar mass of gas D by setting up a ratio between the mass of 5.0 dm3 of gas D and the mass of 5.0 dm3 of C2H2.🔍 Question 51: At the same temperature and pressure, 2.0 dm3 of a gas with the molecular formula CO2 has a mass of 8.0 g, while 3.0 dm3 of gas E has a mass of 4.5 g. What is the molar mass of gas E?Given: mass of 2.0 dm3 of CO2 = 8.0 g, mass of 3.0 dm3 of gas E = 4.5 g R.T.F: Molar mass of gas E = ?Mass of 1 dm3 of gas E = 4.5 g Mass of 3 dm3 of gas E = 3 × 4.5 = 13.5 gMolar mass of gas E = (13.5 g) × (Molar mass of CO2) / (8.0 g)🔍 Question 52: Under the same temperature and pressure, 4.0 dm3 of a gas with the molecular formula H2 has a mass of 2.0 g, while 1.5 dm3 of gas F has a mass of 3.6 g. Determine the molar mass of gas F.Given: mass of 4.0 dm3 of H2 = 2.0 g, mass of 1.5 dm3 of gas F = 3.6 g R.T.F: Molar mass of gas F = ?Mass of 1 dm3 of gas F = 3.6 g Mass of 4 dm3 of gas F = 4 × 3.6 = 14.4 gMolar mass of gas F = (14.4 g) × (Molar mass of H2) / (2.0 g)🔍 Question 53: At the same temperature and pressure, 1.2 dm3 of a gas with the molecular formula CH4 has a mass of 3.0 g, while 2.5 dm3 of gas G has a mass of 4.0 g. Find the molar mass of gas G.Given: mass of 1.2 dm3 of CH4 = 3.0 g, mass of 2.5 dm3 of gas G = 4.0 g R.T.F: Molar mass of gas G = ?Mass of 1 dm3 of gas G = 4.0 g Mass of 2.5 dm3 of gas G = 2.5 × 4.0 = 10.0 gMolar mass of gas G = (10.0 g) × (Molar mass of CH4) / (3.0 g)
Concept Explanation: When comparing the masses of gases at the same temperature and pressure, we can calculate the mass of one gas based on the mass of the same volume of another gas. This is possible because equal volumes of gases at the same conditions contain an equal number of particles.
In this scenario, a flask containing gaseous C2H2 was weighed at a measured temperature and pressure, with a resulting mass of 1.50 g. The flask was then flushed and filled with nitrogen at the same temperature and pressure. We need to determine the mass of nitrogen in the flask.
To find the mass of nitrogen, we use the principle that the masses of equal volumes of gases at the same conditions are proportional to their molar masses. We set up a ratio between the molar mass of nitrogen and the molar mass of C2H2, and then solve for the mass of nitrogen using the given mass of C2H2.
🔍 Question 54: A container holding gaseous H2 was weighed at a specific temperature and pressure, and its mass was found to be 2.50 g. The container was then purged and filled with oxygen at the same temperature and pressure. Calculate the mass of the oxygen in the container. Given: mass of H2 = 2.50 g R.T.F: mass of the same volume of oxygen?
🔍 Question 55: A vessel filled with gaseous CO2 was weighed under certain temperature and pressure conditions, yielding a mass of 3.75 g. The vessel was then emptied and filled with helium at the same temperature and pressure. Determine the mass of the helium in the vessel. Given: mass of CO2 = 3.75 g R.T.F: mass of the same volume of helium?
🔍 Question 56: A flask containing gaseous CH4 was weighed at a specific temperature and pressure, and its mass was determined to be 1.80 g. The flask was then evacuated and filled with argon at the same temperature and pressure. Find the mass of the argon in the flask. Given: mass of CH4 = 1.80 g R.T.F: mass of the same volume of argon?
📝 Answer 54: To calculate the mass of oxygen in the container, we can use the principle of proportional masses. Since the mass of H2 is 2.50 g, we can set up the following ratio:
Molar mass of oxygen / Molar mass of H2 = Mass of oxygen / Mass of H2
From this ratio, we can solve for the mass of oxygen:
Mass of oxygen = (Molar mass of oxygen / Molar mass of H2) * Mass of H2
📝 Answer 55: Similar to the previous question, we can set up a ratio between the molar mass of helium and the molar mass of CO2 to find the mass of helium in the vessel.
📝 Answer 56: Using the principle of proportional masses, we can calculate the mass of argon in the flask by setting up a ratio between the molar mass of argon and the molar mass of CH4.