Question

give the following chemical formula,molar mass,&% composition of the following problems.Round to the nearest tenths place
1)strontium Arsenide

Answer 1

To determine the molar mass and % composition of strontium arsenide (Sr₃As₂), we first need to identify its chemical formula and calculate the molar masses of each component.

### 1. Chemical Formula of Strontium Arsenide:
Strontium arsenide is typically represented as Sr₃As₂.

### 2. Molar Mass Calculation:
We will use the approximate atomic masses for the elements involved:
- Strontium (Sr): approximately 87.62 g/mol
- Arsenic (As): approximately 74.92 g/mol

**Molar Mass of Sr₃As₂**:
\[
\text{Molar mass of Sr₃As₂} = (3 \times 87.62 \, \text{g/mol}) + (2 \times 74.92 \, \text{g/mol})
\]

Calculating it step by step:
- Molar mass of Sr:
\[
3 \times 87.62 = 262.86 \, \text{g/mol}
\]
- Molar mass of As:
\[
2 \times 74.92 = 149.84 \, \text{g/mol}
\]

Now, combine them:
\[
\text{Total Molar Mass} = 262.86 + 149.84 = 412.70 \, \text{g/mol}
\]

### 3. % Composition:
To calculate the percentage composition of each element in Sr₃As₂, we use the formula:

\[
\text{Percent} = \left( \frac{\text{mass of element in formula}}{\text{molar mass of compound}} \right) \times 100
\]

#### % Strontium (Sr):
\[
\text{% Sr} = \left( \frac{262.86}{412.70} \right) \times 100 \approx 63.7\%
\]

#### % Arsenic (As):
\[
\text{% As} = \left( \frac{149.84}{412.70} \right) \times 100 \approx 36.3\%
\]

### Summary:
- **Chemical Formula**: Sr₃As₂
- **Molar Mass**: 412.7 g/mol
- **% Composition**:
- % Strontium (Sr): 63.7%
- % Arsenic (As): 36.3%