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Chapter 3 SABIS Grade 10 Part 4

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✅Lesson 13✅: Avogadro's Number and Molar Mass 🧪📊

Let's dive into the fascinating world of Avogadro's number and molar mass! 🚀

📝 Prerequisite Quiz 📝 Choose the correct answer for each question:

  1. Avogadro's number represents the number of particles in _______. A) 1 mole of gas B) 1 gram of gas C) 1 liter of gas D) 1 cubic meter of gas

  2. A mole is defined as _______. A) 6.02 × 10²³ particles B) 6.02 × 10⁻²³ particles C) 6.02 × 10²³ grams D) 6.02 × 10⁻²³ grams

  3. Atomic mass units (amu) were introduced because _______. A) the masses of atoms and molecules are too large to be measured in grams B) the masses of atoms and molecules are too small to be measured in grams C) the masses of atoms and molecules cannot be accurately measured D) the masses of atoms and molecules are equal to their number of particles

  4. The atomic mass of carbon-12 is defined as _______. A) 12 amu B) 6 amu C) 1 amu D) 24 amu

  5. The conversion factor from grams to amu is _______. A) 1 gram = 6.02 × 10²³ amu B) 1 gram = 1 amu C) 1 gram = 12 amu D) 1 gram = 1/6.02 × 10²³ amu

Awesome! Let's check your answers. 📝✅

Explanation: Avogadro's number, which is approximately 6.02 × 10²³, represents the number of particles in one mole of a substance. A mole is a unit that allows us to count particles on a macroscopic scale. The concept of atomic mass units (amu) was introduced because the masses of single atoms and molecules are too small to be measured in grams. One amu is defined as 1/12th of the mass of a carbon-12 atom. By using conversion factors, we can convert between grams and amu.

Now, let's move on to the next section to explore more about molar mass and its applications. 💡🔬

Examples:

  1. Suppose we have a sample of oxygen gas (O2). Each oxygen atom has an atomic mass of 16 amu. The molecular mass of oxygen gas (O2) is obtained by adding the atomic masses of two oxygen atoms, which gives us 16 + 16 = 32 amu.

  2. Let's consider a mole of oxygen gas (O2). Since the molecular mass of O2 is 32 amu, the mass of one mole of oxygen gas is 32 grams. This relationship holds true for any substance: the molar mass of a substance expressed in grams is numerically equal to its molecular or atomic mass expressed in atomic mass units (amu).

End of Lesson Quiz 📝🔍 Now, let's test your knowledge with a few questions:

  1. What is the molar mass of carbon dioxide (CO2)? A) 12 grams B) 22 grams C) 44 grams D) 32 grams

  2. How many moles of hydrogen atoms are there in one mole of water (H2O)? A) 1 mole B) 2 moles C) 3 moles D) 4 moles

  3. The volume of one mole of any gas at STP conditions is _______. A) 22.4 cm³ B) 22.4 dm³ C) 22.4 liters D) 22.4 m³

  4. The molecular formula of glucose (C6H12O6) corresponds to _______. A) 6 moles of carbon atoms, 12 moles of hydrogen atoms, and 6 moles of oxygen atoms B) 1 mole of carbon atoms, 2 moles of hydrogen atoms, and 1 mole of oxygen atoms C) 12 moles of carbon atoms, 6 moles of hydrogen atoms, and 12 moles of oxygen atoms D) 6 moles of carbon atoms, 6 moles of hydrogen atoms, and 6 moles of oxygen atoms

Brilliant! You've completed Lesson 13 with flying colors. Avogadro's number and molar mass are crucial concepts in chemistry that help us understand the relationships between particles and their masses. If you have any questions, feel free to ask. Keep up the great work! 🌟😊

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