Daily Science feb

How many grams of CH 4 is needed to produce 50.0 g CHCl 3 ?

CH 4 + 3Cl 2  CHCl 3 +3HCl Lithium reacts spontaneously with bromine to produce lithium bromide. Write the balanced chemical equation for the reaction. If 25.0 g of lithium and 25.0 g of bromine are present at the beginning of the reaction, determine the limiting reactant the mass of lithium bromide produced the mass of the excess

Percent Yield

pg. 85

Percent Yield

When you determine the amount of product from a balanced chemical equation you are finding the theoretical yield rarely do scientists get the theoretical yield in the lab, we measure the actual yield need to know the efficiency-- determine percent yield

Calculating percent yield

percent yield= actual yield (from lab) / theoretical yield (from calculations) x 100 expressed as a percent

Example

When potassium chromate (K 2 CrO 4 ) is added to a solution containing 0.500 g silver nitrate, solid silver chromate (Ag 2 CrO 4 ) is formed. determine the theoretical yield of the silver chromate precipitate if 0.455 g of silver chromate is obtained, calculate the percent yield.

Practice Problems

Aluminum hydroxide is often present in antacids to neutralize stomach acid (HCl). If 14.0 g aluminum hydroxide is present in an antacid tablet, determine the theoretical yield of aluminum chloride produce when the tablet reacts with stomach acid. If the actual yield of aluminum chloride from this tablet is 22.0 g, what is the percent yield?

Al(OH) 3 +3HCl --> AlCl 3 +3H 2 O