Question
Calculate the percentage by mass of each of the element in the following compounds.
a) chloro - trifluoro methane
b) Calcium phosphate- Ca3(PO4)2
a) chloro - trifluoro methane
b) Calcium phosphate- Ca3(PO4)2
Answers
GPT-4o mini
To calculate the percentage by mass of each element in a compound, you'll follow these steps:
1. Find the molar mass of the compound by adding up the atomic masses of each element in the molecule.
2. Calculate the percentage by mass of each element by dividing the mass of that element by the total molar mass of the compound, and then multiplying by 100.
### a) Chloro-trifluoro methane (CHF₃Cl)
1. **Determine the molar mass:**
- Carbon (C): 12.01 g/mol
- Hydrogen (H): 1.01 g/mol
- Fluorine (F): 19.00 g/mol (there are 3 F atoms)
- Chlorine (Cl): 35.45 g/mol
Molar mass = \(1 \times 12.01 + 1 \times 1.01 + 3 \times 19.00 + 1 \times 35.45\)
\[
= 12.01 + 1.01 + 57.00 + 35.45 = 105.47 \, \text{g/mol}
\]
2. **Calculate the percentage by mass of each element:**
- %C = \(\frac{12.01}{105.47} \times 100 = 11.39\%\)
- %H = \(\frac{1.01}{105.47} \times 100 = 0.96\%\)
- %F = \(\frac{57.00}{105.47} \times 100 = 54.05\%\)
- %Cl = \(\frac{35.45}{105.47} \times 100 = 33.58\%\)
### b) Calcium phosphate (Ca₃(PO₄)₂)
1. **Determine the molar mass:**
- Calcium (Ca): 40.08 g/mol (there are 3 Ca atoms)
- Phosphorus (P): 30.97 g/mol (there are 2 P atoms)
- Oxygen (O): 16.00 g/mol (there are 8 O atoms since PO₄ has 4 O and there are 2 units)
Molar mass = \(3 \times 40.08 + 2 \times 30.97 + 8 \times 16.00\)
\[
= 120.24 + 61.94 + 128.00 = 310.18 \, \text{g/mol}
\]
2. **Calculate the percentage by mass of each element:**
- %Ca = \(\frac{120.24}{310.18} \times 100 = 38.76\%\)
- %P = \(\frac{61.94}{310.18} \times 100 = 19.98\%\)
- %O = \(\frac{128.00}{310.18} \times 100 = 41.27\%\)
### Summary of percentages:
- **Chloro-trifluoro methane (CHF₃Cl):**
- %C: 11.39%
- %H: 0.96%
- %F: 54.05%
- %Cl: 33.58%
- **Calcium phosphate (Ca₃(PO₄)₂):**
- %Ca: 38.76%
- %P: 19.98%
- %O: 41.27%
1. Find the molar mass of the compound by adding up the atomic masses of each element in the molecule.
2. Calculate the percentage by mass of each element by dividing the mass of that element by the total molar mass of the compound, and then multiplying by 100.
### a) Chloro-trifluoro methane (CHF₃Cl)
1. **Determine the molar mass:**
- Carbon (C): 12.01 g/mol
- Hydrogen (H): 1.01 g/mol
- Fluorine (F): 19.00 g/mol (there are 3 F atoms)
- Chlorine (Cl): 35.45 g/mol
Molar mass = \(1 \times 12.01 + 1 \times 1.01 + 3 \times 19.00 + 1 \times 35.45\)
\[
= 12.01 + 1.01 + 57.00 + 35.45 = 105.47 \, \text{g/mol}
\]
2. **Calculate the percentage by mass of each element:**
- %C = \(\frac{12.01}{105.47} \times 100 = 11.39\%\)
- %H = \(\frac{1.01}{105.47} \times 100 = 0.96\%\)
- %F = \(\frac{57.00}{105.47} \times 100 = 54.05\%\)
- %Cl = \(\frac{35.45}{105.47} \times 100 = 33.58\%\)
### b) Calcium phosphate (Ca₃(PO₄)₂)
1. **Determine the molar mass:**
- Calcium (Ca): 40.08 g/mol (there are 3 Ca atoms)
- Phosphorus (P): 30.97 g/mol (there are 2 P atoms)
- Oxygen (O): 16.00 g/mol (there are 8 O atoms since PO₄ has 4 O and there are 2 units)
Molar mass = \(3 \times 40.08 + 2 \times 30.97 + 8 \times 16.00\)
\[
= 120.24 + 61.94 + 128.00 = 310.18 \, \text{g/mol}
\]
2. **Calculate the percentage by mass of each element:**
- %Ca = \(\frac{120.24}{310.18} \times 100 = 38.76\%\)
- %P = \(\frac{61.94}{310.18} \times 100 = 19.98\%\)
- %O = \(\frac{128.00}{310.18} \times 100 = 41.27\%\)
### Summary of percentages:
- **Chloro-trifluoro methane (CHF₃Cl):**
- %C: 11.39%
- %H: 0.96%
- %F: 54.05%
- %Cl: 33.58%
- **Calcium phosphate (Ca₃(PO₄)₂):**
- %Ca: 38.76%
- %P: 19.98%
- %O: 41.27%