Realistically, there is no reactions can be 100% completion. That's why we have to calculate the percentage of product actually formed.
As we have leaned stoichiometry calculation to predict what's the product by converting from one reactant to another reactant, and now we can determind what's the difference between
ACTUAL YIELD and THEORETICAL YIELD
Actual Yield (What you ACTUALLY obtain from the reaction)
Theoretical Yield (What you EXPECT to get from the reaction)
So, when we want to find out what's the difference between "ACTUALLY YIELD" and "THEORETICAL YIELD". We can do it mathematically by mutiplying 100%
Actual Yield (What you ACTUALLY obtain from the reaction) x 100%
Theoretical Yield (What you EXPECT to get from the reaction)
As a result, the percentage that you get will be the PERCENT YIELD.
Ex 1)
35.0 mL of 2.00 M Ca(OH)2 produced only 3.92 of CaCl2. What would the percent yield of the reaction be?
1)First, we have to consider what are the steps to get to the answer.
If we get mL (Volumn) and M (Molarity), then we can get the mol (mole) by the molarity equation WE 'VE LEARNED BEFORE. (BETTER REVIEW)
2M x ( 35 ) (L) = 0.07 mol of Ca(OH)2 x 1 mol of CaCl2 x (40.1 + 35.5x2)
1000 1 mol of Ca(OH)2 1 mol of CaCl2
= 7.7777g of CaCl2
Actual Yield 3.92g of CaCl2 x 100% = 50.4% (SIGFIG)
Theoretical Yield 7.78g of CaCl2
Part2 Percent Purity
The ratio of the mass of pure substance to mass of impure sample expressed as a percent!
% Percent Pure = Mass of Pure Substance x 100%
Mass of Impure Sample
By following this equation, the impure sample is heavier than the pure substance, as the impure one contains other substances in it. Once you get the answer over 100%, then you may make a mistake in your calculation.
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