Limiting Reagents and Stoichiometry

This video tutorial provides a comprehensive review of stoichiometry, covering key concepts such as the definition of stoichiometry, limiting reagents, and stoichiometry calculations. It includes detailed problem-solving examples and explains how to calculate percent yield in chemical reactions. The tutorial is designed to help students understand the relationships between chemical quantities in reactions and improve their problem-solving skills in chemistry.

What is stoichiometry primarily concerned with?

• The color changes in reactions

• The relationship between chemical quantities in reactions

• The energy changes in reactions

• The speed of chemical reactions

What is a limiting reagent in a chemical reaction?

• The reactant that is in excess

• The reactant that runs out first

• The catalyst used in the reaction

• The product formed in the largest amount

How can you identify a limiting reagent problem?

• By the speed of the reaction

• By the color of the reactants

• By the temperature of the reaction

• By being given amounts of two reactants

In a reaction between aluminum and iron oxide, how many moles of aluminum are needed to react with 10 moles of iron oxide?

• 5 moles

• 6.67 moles

• 10 moles

• 20 moles

When given 27 grams of copper, how many grams of chromium are needed to react completely?

• 25 grams

• 10.5 grams

• 14.6 grams

• 20 grams

What is the percent yield if the actual yield is 38.1 grams and the theoretical yield is 42 grams?

• 95%

• 80%

• 85%

• 90%

How do you calculate the percent yield of a reaction?

• Add the actual yield to the theoretical yield

• Subtract the actual yield from the theoretical yield

• Divide the actual yield by the theoretical yield and multiply by 100

• Divide the theoretical yield by the actual yield and multiply by 100

In a limiting reagent problem, what determines the maximum amount of product that can be formed?

• The reactant in excess

• The reactant that is completely used up

• The catalyst used

• The fastest reacting substance

If 72.9 grams of iron sulfide react with 79.8 grams of hydrochloric acid, how many grams of the excess reactant are left over?

• 25.4 grams

• 20.2 grams

• 15.3 grams

• 10.2 grams

What is the first step in solving a stoichiometry problem involving grams?

• Convert grams to liters

• Write a balanced chemical equation

• Calculate the percent yield

• Determine the color of the reactants