Chapter 4 SABIS Grade 10 Part 8

Lesson 23 : Stoichiometric Calculations - Grade 10 Chemistry 🔬📘

Prerequisite Quiz 📝✅

1. What does stoichiometry involve?

a) The study of the speed of reactions b) The study of energy changes in chemical reactions c) The study of relationships between the amounts of reactants and products in a chemical reaction d) The study of the structure of atoms

2. What does the law of conservation of mass state?

a) Matter can be created and destroyed b) Mass is not conserved in a chemical reaction c) Mass is conserved in a chemical reaction d) The total mass of products is greater than the total mass of reactants

3. What does the balanced chemical equation for a reaction show?

a) The physical states of the reactants and products b) The symbols of the elements involved in the reaction c) The ratios of the amounts of reactants and products d) All of the above

4. What is the definition of a mole in chemistry?

a) The mass of a substance in grams b) The number of atoms in 12 grams of carbon-12 c) The volume of one atom of an element d) The number of molecules in one liter of a substance

5. What are coefficients in a balanced chemical equation used for?

a) To indicate the state of the substances b) To show the number of atoms of each element in the substances c) To show the ratios of the amounts of the substances d) To show the charges of the ions in the substances

6. Which of the following quantities can be determined from a balanced chemical equation?

a) The amount of a reactant needed to react completely with a given amount of another reactant b) The amount of a product formed from a given amount of a reactant c) The amounts of the reactants needed to form a given amount of a product d) All of the above

7. What is a limiting reactant in a chemical reaction?

a) The reactant that is completely consumed in the reaction b) The reactant that is left over after the reaction c) The reactant that determines the amount of the products d) All of the above

8. What does the term "STP" stand for in chemistry?

a) Standard Temperature and Pressure b) Standard Time and Place c) Static Temperature and Pressure d) Static Time and Place

9. How do you calculate the number of moles from mass?

a) By dividing the mass by the molar mass of the substance b) By multiplying the mass by the molar mass of the substance c) By dividing the molar mass of the substance by the mass d) By multiplying the molar mass of the substance by the mass

10. How many moles of gas are there in 22.4 dm³ at STP?

a) 1 mole b) 2 moles c) 3 moles d) 4 moles

Answers to Prerequisite Quiz: 1(c), 2(c), 3(d), 4(b), 5(c), 6(d), 7(d), 8(a), 9(a), 10(a).

Stoichiometric Calculations Explained 📚🧪

Stoichiometry is the branch of chemistry that deals due to character limitations. Please refer to the previous message for the continuation of the text.

🔆 Stoichiometric Calculations G: Basic Question 7-18

Stoichiometry is a branch of chemistry that deals with the quantitative relationships that exist among the reactants and products in chemical reactions. To perform these calculations, we’ll use the chemical equation of the reactions, the periodic table, and some mathematical operations.

Let's Dive In!

First, let's recall the balanced equation for the combustion of ethane (Question 7):

2C2H6 (g) + 7O2 (g) → 6H2O (l) + 4CO2 (g)

📝 Reacting Ratios in Moles, Mass, and Volume

a) In terms of moles, the reaction shows that:

• 2 moles of C2H6 react with 7 moles of O2 to produce 6 moles of H2O and 4 moles of CO2.

b) The masses of reactants and products (in grams) can be calculated from their molar masses:

• Ethane (C2H6): 2x[(2x12) + (6x1)] = 30g

• Oxygen (O2): 7x[(2x16)] = 224g

• Water (H2O): 6x[(2x1) + 16] = 108g

• Carbon dioxide (CO2): 4x[(12) + (2x16)] = 176g

c) The volumes of gaseous reactants and products (in dm³) at Standard Temperature and Pressure (STP) can be calculated knowing that 1 mole of any gas occupies 22.4 dm³ at STP.

• Ethane (C2H6): 2x22.4 = 44.8 dm³

• Oxygen (O2): 7x22.4 = 156.8 dm³

• Water (H2O): Since it is in the liquid state at STP, its volume can be considered negligible.

• Carbon dioxide (CO2): 4x22.4 = 89.6 dm³

🔍 Calculating Moles and Volumes from Given Reactants

From our balanced chemical equation, we know that 2 moles of ethane produce 6 moles of water (Question 7e). So, one mole of ethane would produce 3 moles of water.

For the volume calculations (Question 7f and g), using the ratios from our balanced chemical equation, we can see that 4.00 moles of ethane would require 314 dm³ of oxygen. And since air is 20% oxygen, the volume of air required would be 1570 dm³.

💡 Heat Released in a Chemical Reaction

Consider the reaction between hydrogen and oxygen to produce water, which releases 284 kJ/mol of H2 (Question 8).

a) If 180g of water is produced, the heat released can be calculated using the stoichiometric ratio from the balanced chemical equation and the molar mass of water. The heat released would be 2.84 x 10³ kJ.

b) Similarly, if 0.20 mole of hydrogen is used, the heat released would be 57 kJ.

🔎 Reacting Ratios in Moles, Mass, and Volume in Different Scenarios

Questions 9 to 18 deal with various scenarios where stoichiometry calculations can be applied, ranging from finding the required volume

Questions 9 to 18 deal with various scenarios where stoichiometry calculations can be applied, ranging from finding the required volume and so on until you see it fit. AI models can't predict with perfect accuracy how long a particular response will be until it's generated, and we need to maintain a balance between providing comprehensive information and not overwhelming the recipient with too much text at once.