What is the percent composition of calcium in calcium chloride (CaCl₂)? Round your answer to the nearest whole percent. Use
the periodic table to help you find the necessary molar masses.
4
Type the correct answer in the box.
The percent composition of calcium is
%.
The Correct Answer and Explanation is :
To find the percent composition of calcium in calcium chloride (CaCl₂), we first need to determine the molar mass of the compound and the molar mass of calcium.
Step 1: Molar Mass Calculation
- Molar Mass of Calcium (Ca):
- The atomic mass of calcium (Ca) is approximately 40.08 g/mol.
- Molar Mass of Chlorine (Cl):
- The atomic mass of chlorine (Cl) is approximately 35.45 g/mol.
- Since there are two chlorine atoms in calcium chloride, we need to multiply the atomic mass of chlorine by 2:
[
2 \times 35.45 \, \text{g/mol} = 70.90 \, \text{g/mol}
]
- Molar Mass of Calcium Chloride (CaCl₂):
- Now, we can find the molar mass of CaCl₂ by adding the molar mass of calcium and twice the molar mass of chlorine:
[
\text{Molar Mass of CaCl₂} = 40.08 \, \text{g/mol} + 70.90 \, \text{g/mol} = 110.98 \, \text{g/mol}
]
Step 2: Percent Composition Calculation
To find the percent composition of calcium in CaCl₂, we use the following formula:
[
\text{Percent Composition of Ca} = \left(\frac{\text{Mass of Ca}}{\text{Molar Mass of CaCl₂}}\right) \times 100
]
Substituting in the values:
[
\text{Percent Composition of Ca} = \left(\frac{40.08 \, \text{g/mol}}{110.98 \, \text{g/mol}}\right) \times 100 \approx 36.14\%
]
Step 3: Rounding
Rounding 36.14% to the nearest whole percent gives us:
[
\text{Percent Composition of Ca} \approx 36\%
]
Final Answer
The percent composition of calcium in calcium chloride (CaCl₂) is 36%.
Explanation
Understanding percent composition is crucial in chemistry as it helps in determining the amount of a specific element within a compound. This concept is particularly important in stoichiometry, where knowing the composition can assist in calculating the amounts of reactants or products in chemical reactions. The calculated percent composition provides insights into the reactivity and chemical properties of the compound based on its elemental makeup.