3.5g of CuCl2.2H2O were dissolved and reacted with excess Na2SO3 in the presence of HCl. After filtration, 1.5g of CuCl crystals was obtained. Calculate the %yield.
1. Write and balance the equation.
2. Convert 3.5g CuCl2.H2O to grams of the product. Use stoichiometry. Here is a worked example. Just follow the steps.
http://www.jiskha.com/science/chemistry/stoichiometry.html
3. %yield = (grams product/theoretical yield in grams)*100.
balanced equation of cucl2.2h2o+na2so3
To calculate the percent yield, we need to compare the actual yield to the theoretical yield.
First, let's calculate the theoretical yield of CuCl crystals:
1 mole of CuCl2.2H2O --> 1 mole of CuCl
The molar mass of CuCl2.2H2O = 63.5 g/mol (Cu) + 2*35.5 g/mol (Cl) + 2*(2*1 g/mol) (H2O) = 170.5 g/mol
The molar mass of CuCl = 63.5 g/mol + 35.5 g/mol = 99 g/mol
The number of moles of CuCl2.2H2O = mass / molar mass = 3.5 g / 170.5 g/mol = 0.0205 mol
Since 1 mole of CuCl2.2H2O produces 1 mole of CuCl, the theoretical yield of CuCl is also 0.0205 mol.
Now, let's calculate the actual yield:
Actual yield = 1.5 g
Finally, we can calculate the percent yield:
Percent yield = (Actual yield / Theoretical yield) * 100
Percent yield = (1.5 g / (0.0205 mol * 99 g/mol)) * 100
Percent yield = (1.5 g / 2.0245 g) * 100
Percent yield = 74.11%
Therefore, the percent yield is approximately 74.11%.
To calculate the percent yield, we need to compare the actual yield of the product (1.5g of CuCl crystals) to the theoretical yield.
1. Determine the moles of CuCl2.2H2O:
To do this, we need to calculate the molar mass of CuCl2.2H2O.
Cu: atomic mass = 63.55g/mol
Cl: atomic mass = 35.45g/mol (x2 since there are two chlorines in the formula)
H2O: molecular mass = (1.01g/mol x 2) + (16.00g/mol) = 18.02g/mol
Molar mass of CuCl2.2H2O:
= (63.55g/mol + (35.45g/mol x 2)) + (18.02g/mol x 2)
= 170.49g/mol
Now, calculate the moles of CuCl2.2H2O by dividing the given mass by the molar mass:
moles = mass / molar mass
moles = 3.5g / 170.49g/mol
moles = 0.0205 mol
2. Determine the stoichiometry of the reaction:
From the balanced equation between CuCl2 and Na2SO3, we can determine the mole ratio between CuCl2 and CuCl crystals:
CuCl2 + Na2SO3 + 4HCl → CuCl + Na2SO4 + 2H2O
1 mol of CuCl2 produces 1 mol of CuCl
3. Calculate the theoretical yield of CuCl crystals:
By knowing the stoichiometry and the moles of CuCl2 from step 1, we can calculate the moles of CuCl formed in the reaction.
moles of CuCl = moles of CuCl2 = 0.0205 mol
Then, convert the moles of CuCl to grams using the molar mass of CuCl (63.55 g/mol):
theoretical yield = moles of CuCl x molar mass of CuCl
theoretical yield = 0.0205 mol x 63.55 g/mol
theoretical yield = 1.30 g
4. Calculate the percent yield:
Percent yield = (actual yield / theoretical yield) x 100%
Given that the actual yield is 1.5g of CuCl crystals:
percent yield = (1.5g / 1.30g) x 100%
percent yield = 115.38%
Therefore, the percent yield of CuCl crystals in this reaction is approximately 115.38%.