When HgO is heated, it decomposes into elemental mercury and diatomic oxygen gas. If 42.9 g of Hg is obtained from 70.1 g of the mercuric oxide, what is the percent yield of the reaction?
2HgO ==> 2Hg + O2
mol HgO = 70.1g/molar mass HgO = ?
Use the coefficients to convert mols HgO to mols Hg. The ratio is 2:2 which is 1:1; therefore, mols HgO = mols Hg.
Convert mols Hg to grams. g = mols x atomic mass. This is the theoretical yield (TY). The actual yeld (AY) = 42.9.
%yield = (AY/TY)*100 = ?
To determine the percent yield of the reaction, we first need to find the theoretical yield, which is the maximum amount of mercury (Hg) that can be obtained from the given amount of mercuric oxide (HgO).
1. Start by calculating the molar masses of HgO and Hg:
- Molar mass of HgO = molar mass of Hg + molar mass of O
- Molar mass of HgO = 200.59 g/mol + 15.99 g/mol (oxygen has atomic mass 15.99 g/mol)
- Molar mass of HgO = 216.58 g/mol
- Molar mass of Hg = 200.59 g/mol
2. Convert the given mass of HgO to moles:
- Moles of HgO = mass of HgO / molar mass of HgO
- Moles of HgO = 70.1 g / 216.58 g/mol
- Moles of HgO ≈ 0.3232 mol (rounded to four decimal places)
3. Use the balanced chemical equation to find the stoichiometric ratio between HgO and Hg:
- The balanced equation is: 2HgO → 2Hg + O2
- From the balanced equation, we know that 2 moles of HgO produce 2 moles of Hg, so the stoichiometric ratio is 1:1.
4. Calculate the moles and mass of Hg that can be obtained based on the moles of HgO:
- Moles of Hg = moles of HgO
- Moles of Hg = 0.3232 mol (rounded to four decimal places)
- Mass of Hg = moles of Hg × molar mass of Hg
- Mass of Hg = 0.3232 mol × 200.59 g/mol
- Mass of Hg ≈ 64.96 g (rounded to two decimal places)
Now, we can calculate the percent yield:
5. Percent yield = (Actual yield / Theoretical yield) × 100%
- Actual yield: Given as 42.9 g
- Theoretical yield: Calculated as 64.96 g
- Percent yield = (42.9 g / 64.96 g) × 100%
- Percent yield ≈ 66.1% (rounded to one decimal place)
Therefore, the percent yield of the reaction is approximately 66.1%.