A student used 3.27g of Zn to react with excess HCl and obtains 6.47g ZnCl2. What is the percent yield?
First, calculate theoretical yield (TY).
Zn + 2HCl ==> ZnCl2 + H2
mols Zn = grams/atomic mass = about 0.05 but that's an estimate.
Using the coefficients in the balanced equation, convert mols Zn to mols ZnCl2.
That's about 0.05 x (1 mol ZnCl2/1 mol Zn) = estd 0.05 mols ZnCl2.
g ZnCl2 = mols ZnCl2 x molar mass ZnCl2. This is the TY.
Actual yield (AY) is 6.47g.
%yield = (AY/TY)*100 = ?
To calculate the percent yield, we need to compare the actual yield to the theoretical yield.
First, let's find the theoretical yield, which is the maximum amount of product that can be formed based on the limiting reactant. In this case, Zn is the limiting reactant because it is completely consumed during the reaction.
The molar mass of Zn is 65.38 g/mol, so we can calculate the moles of Zn used:
moles of Zn = mass of Zn / molar mass of Zn
moles of Zn = 3.27 g / 65.38 g/mol
moles of Zn = 0.05 mol
From the balanced chemical equation, we know that 1 mole of Zn reacts with 2 moles of HCl to form 1 mole of ZnCl2. Therefore, the theoretical yield of ZnCl2 can be calculated using the stoichiometric ratio:
moles of ZnCl2 = moles of Zn × (1 mole ZnCl2 / 1 mole Zn)
moles of ZnCl2 = 0.05 mol × (1 mol ZnCl2 / 1 mol Zn)
moles of ZnCl2 = 0.05 mol
To find the mass of the theoretical yield of ZnCl2, we can use the molar mass of ZnCl2, which is 136.29 g/mol:
mass of ZnCl2 = moles of ZnCl2 × molar mass of ZnCl2
mass of ZnCl2 = 0.05 mol × 136.29 g/mol
mass of ZnCl2 = 6.82 g
Now, we can calculate the percent yield:
percent yield = (actual yield / theoretical yield) × 100%
percent yield = (6.47 g / 6.82 g) × 100%
percent yield ≈ 94.8%
Therefore, the percent yield of ZnCl2 is approximately 94.8%.
To calculate the percent yield, we need to compare the actual yield (the amount of ZnCl2 obtained) with the theoretical yield (the maximum amount of ZnCl2 that can be formed based on the balanced equation).
First, we need to determine the theoretical yield. We can do this by using stoichiometry and the balanced chemical equation for the reaction between Zn and HCl.
The balanced chemical equation is: Zn + 2HCl -> ZnCl2 + H2
From the equation, we can see that 1 mole of Zn will react with 2 moles of HCl to produce 1 mole of ZnCl2.
1 mole of Zn (atomic weight: 65.38 g/mol) will react with 2 moles of HCl (molar mass: 36.46 g/mol) to produce 1 mole of ZnCl2 (molar mass: 136.29 g/mol).
To calculate the theoretical yield, we can use the formula:
Theoretical Yield = (Actual mass of Zn / molar mass of Zn) * (molar mass of ZnCl2 / molar mass of Zn)
Theoretical Yield = (3.27 g Zn / 65.38 g/mol) * (136.29 g/mol / 65.38 g/mol) = 6.79 g ZnCl2
Now, we can calculate the percent yield:
Percent Yield = (Actual Yield / Theoretical Yield) * 100
Percent Yield = (6.47 g ZnCl2 / 6.79 g ZnCl2) * 100 = 95.1%
Therefore, the percent yield is 95.1%.