Warm-Up What happens if you don’t have enough of one of your reactants?

Limiting Reactants

Vocabulary Limiting Reactant – the reactant that you run out of first in a chemical reaction Reactant in Excess – the reactant that you will have left over after all of the limiting reactant is consumed

Practice Problem Identify the limiting reactant and the mass of water produced when 500.0 g of hydrogen gas reacts with 1000.0 g of oxygen gas at STP.

Step 1 Determine how many moles of the product can be produced from each given amount of reactant.

Step 2 Determine which reactant will produce the fewest moles of product. This is your limiting reactant, and therefore gives you the amount of product you can form.

Step 3 Convert the moles of product that will be produced to the units that the problem asks you for if you need to (in this case mass). This is a one-step conversion problem using your islands.

Practice What mass of barium nitride is produced from the reaction between 22.6 g of barium and 4.2 g of nitrogen gas? What is you limiting reactant?

Percent Yield Expected Yield – amount of product that should be formed Actual Yield – amount of product that actually forms

Practice Determine the percent yield for the reaction above if only 21.5 g of barium nitride was actually collected.

Warm-Up Have your pre-lab out on your desk! Calculate the mass of sodium bromide formed when 50.2 g of nitrogen tribromide reacts with 57.5 g of sodium hydroxide. Unbalanced Reaction: (balance this first!) NBr3 + NaOH  N2 + NaBr + HBrO

Pre-Lab #1 Baking Soda: NaHCO3 Vinegar: HC2H3O2

Pre-Lab #2 NaHCO3 (s) + HC2H3O2 (aq)  NaC2H3O2 (aq) + CO2 (g) + H2O (l)

Pre-Lab #3 NaHCO3 : 84.01 g HC2H3O2 : 60.05 g NaC2H3O2 : 82.03 g

Limiting Reactants Lab Change to 65 mL of Vinegar! Erlenmeyer flask Graduated cylinder Swirl gently (2 minutes) Hot plates Balances