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Calculate the percent yield if 1.95 g of Ca(OH)2 reacts with excess HCl to produce 2.50 g of CaCl2. Ca(OH)2 + 2HCl → CaCl2 + 2H2OTheoretical yield?Percent yield?

Sagot :

The first step is to write a balanced chemical equation.

[tex]Ca(OH)_2+\text{ 2HCl}\rightarrow CaCl_2+2H_2O[/tex]

The above equation is already balanced.

Now lets write what we have.

Ca(OH)2 = 1.95g

CaCl2 = 2.50g

We already know that HCl is in excess, meaning Ca(OH)2 is the limiting reagent.

%Yield = (actual yield/theoretical yield) x 100

Lets first calculate the theoretcal yield. To find this we need to first calculate the number of moles of CaCl2.

n = m/M where m is the mass and M is the molar mass of CaCl2

n = 2.50g/110,98 g/mol

n = 0.0225 mol

Theoretical Yield is the amount of product that would have been produced if all of the limiting reagent reacted and it was 100% pure. The limiting reagent is used up first in a reaction and controls the amount of product that can be produced.

The actual yield of CaCl2 we were given, which is 2.50g of CaCl2.

For every 1 mole of Ca(OH)2, 1 mole of CaCl2 is produced

n = 1.95g/74.09 g/mol

n = 0.0263 mol

Therefore the number of moles of CaCl2 = 0.0263 mol

mass of CaCl2 = nM

m = 0.0263 mol x 110,98 g/mol

m = 2.92 g

So the theoretical yield of CaCl2 = 2.92g

percentage yield = (2.50g/2.92)*100

percentage yield = 85.62%