Who can propel a rocket the farthest?

The best scientist will win!

• Using the reaction between Oxygen and Hydrogen Gas to create energy

• Test 3 ratios in attempt to create the best rocket!

Things to think about the rockets flight

• What ratio propelled the rocket furthest?

• Are there any ratios with unused gas?

• At what point does the hydrogen or oxygen stop reacting?

What do you notice in the Copper Silver Nitrate Lab?

• Which reactant seems to have disapeared?

• What is left?

• Can any more silver be made at this point?

Limiting Reactants and Excess

• What is the Limiting Reagent (Reactant)?It is the substance in a chemical reaction that runs out first.

• The limiting reactant (reagent) determines how much product you can make.

• If you are given amounts of more than one reactant, determine how much product you can make with each of them. Whichever produces the LEAST amount of product is your limiting reagent.

Practice ProblemsConsider the reaction:

2 Al + 3 I2 2 AlI3

Determine the limiting reagent and the theoretical yield of the product,

aluminum iodide, if one starts with:

a). 1.20 moles of Al and 2.40 moles of iodine

b). 1.20 grams of Al and 2.40 grams of iodine

c) In the problem b. above, how many grams of excess reactant will remain?

15.00 g aluminum sulfide and 12.00 g of water react until the limiting reagent is used up. Here is the balanced equation for the reaction.

Al2S3 + 6 H2O 2 Al(OH)3 + 3 H2S

a.) What is the maximum mass of H2S which can be formed from these reagents ?

b). Which is the limiting reagent?

c). How much of the excess reactant is used up?

Example: In the reaction between nitrogen gas and hydrogen gas producing ammonia:

a.) If you start with 14 grams of N2 and 6.0 grams of H2, what will be the limiting reactant? What is the theoretical yield of product?

b.) If 10. grams of the product was formed, what would be the percent yield?