Module 7 Intro

Module 7—Chemical Analysis

Read

Have you ever ridden in a vehicle that ran out of gas before reaching the planned destination? A situation like this quickly reminds you that depleting one of the reactants in a chemical process causes the reaction to quit. Chemical reactions don’t have a fuel gauge like a vehicle does, so how can you use your knowledge of stoichiometry to identify the limiting reagent in a reaction?

Read “Identifying Limiting and Excess Reagents” on pages 321 to 323 of your textbook. Work through “SAMPLE problems” 8.2 and 8.3 and the “COMMUNICATION example.”

Self-Check

SC 2. 2.50 mol of propane, C3H8(g), is combusted with 12.0 mol of oxygen gas.

1. Write the balanced chemical equation.
   
   

2. Predict the limiting and excess reagents.
   
   

3. Calculate the volume of CO2(g) produced when the reaction is complete. Assume SATP conditions.

SC 3. 10.0 g of butane, C4H10(g), is combusted with 30.0 g of oxygen gas.

1. Write the balanced chemical equation.

2. Determine the number of moles of each reactant.

3. Predict the limiting and excess reagents.

4. Calculate the mass of CO2(g) produced when the reaction is complete.

SC 4. 2.00 L of methane, CH4(g), is combusted with 9.00 L of oxygen gas. Assume STP conditions.

1. Write the balanced chemical equation.
   
   

2. Determine the number of moles of each reactant.
   
   

3. Predict the limiting and excess reagents.
   
   

4. After the reaction is complete, the atmospheric conditions change. Calculate the volume of CO2(g) produced if the atmospheric pressure is now 99.0 kPa and the temperature is 19.0°C.

SC 5. A 12.0-mL sample of a 0.500-mol/L silver nitrate solution is mixed with 10.0 mL of 0.400-mol/L NaOH(aq). Calculate the mass of precipitate produced in the reaction.