A 0.597 g sample of an unknown compound occupies 245 mL at 305.6 K and 994.1 mmHg. What is the molar mass of the unknown compound?

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ISBN:9781305957404
Author:Steven S. Zumdahl, Susan A. Zumdahl, Donald J. DeCoste
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Chapter1: Chemical Foundations
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**Problem Statement:**

A 0.597 g sample of an unknown compound occupies 245 mL at 305.6 K and 994.1 mmHg. What is the molar mass of the unknown compound?

**Solution:**

To find the molar mass of the unknown compound, we can use the Ideal Gas Law equation: 

\[ PV = nRT \]

Where:
- \( P \) is the pressure,
- \( V \) is the volume,
- \( n \) is the number of moles,
- \( R \) is the universal gas constant, and
- \( T \) is the temperature.

**Given:**
- Mass of the compound (\( m \)): 0.597 g
- Volume (\( V \)): 245 mL = 0.245 L (since 1 L = 1000 mL)
- Temperature (\( T \)): 305.6 K
- Pressure (\( P \)): 994.1 mmHg
- Universal gas constant (\( R \)): 0.0821 L·atm/(K·mol)

First, convert the pressure from mmHg to atm:
\[ P = 994.1 \, \text{mmHg} \times \frac{1 \, \text{atm}}{760 \, \text{mmHg}} = 1.307 \, \text{atm} \]

Next, apply the Ideal Gas Law to solve for the number of moles (\( n \)):
\[ n = \frac{PV}{RT} = \frac{(1.307 \, \text{atm}) \times (0.245 \, \text{L})}{(0.0821 \, \text{L·atm/(K·mol)}) \times (305.6 \, \text{K})} \]

\[ n \approx 0.01289 \, \text{mol} \]

Finally, calculate the molar mass (\( M \)) of the compound:
\[ \text{Molar mass} = \frac{\text{mass}}{\text{moles}} = \frac{0.597 \, \text{g}}{0.01289 \, \text{mol}} \]

\[ M \approx 46.34 \, \text{g/mol} \]

**Conclusion:**
The molar mass of the unknown
Transcribed Image Text:**Problem Statement:** A 0.597 g sample of an unknown compound occupies 245 mL at 305.6 K and 994.1 mmHg. What is the molar mass of the unknown compound? **Solution:** To find the molar mass of the unknown compound, we can use the Ideal Gas Law equation: \[ PV = nRT \] Where: - \( P \) is the pressure, - \( V \) is the volume, - \( n \) is the number of moles, - \( R \) is the universal gas constant, and - \( T \) is the temperature. **Given:** - Mass of the compound (\( m \)): 0.597 g - Volume (\( V \)): 245 mL = 0.245 L (since 1 L = 1000 mL) - Temperature (\( T \)): 305.6 K - Pressure (\( P \)): 994.1 mmHg - Universal gas constant (\( R \)): 0.0821 L·atm/(K·mol) First, convert the pressure from mmHg to atm: \[ P = 994.1 \, \text{mmHg} \times \frac{1 \, \text{atm}}{760 \, \text{mmHg}} = 1.307 \, \text{atm} \] Next, apply the Ideal Gas Law to solve for the number of moles (\( n \)): \[ n = \frac{PV}{RT} = \frac{(1.307 \, \text{atm}) \times (0.245 \, \text{L})}{(0.0821 \, \text{L·atm/(K·mol)}) \times (305.6 \, \text{K})} \] \[ n \approx 0.01289 \, \text{mol} \] Finally, calculate the molar mass (\( M \)) of the compound: \[ \text{Molar mass} = \frac{\text{mass}}{\text{moles}} = \frac{0.597 \, \text{g}}{0.01289 \, \text{mol}} \] \[ M \approx 46.34 \, \text{g/mol} \] **Conclusion:** The molar mass of the unknown
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