A 12.0-liter container holds 709 g of chlorine gas, Cl2, at 35.0 °C. What is the pressure in the container?

21.1 atm

2.39 atm

170 atm

1490 atm

1 answer

To find the pressure of the chlorine gas in the container, we can use the Ideal Gas Law:

\[ PV = nRT \]

Where:

  • \( P \) is the pressure in atm,
  • \( V \) is the volume in liters,
  • \( n \) is the number of moles of gas,
  • \( R \) is the ideal gas constant (0.0821 L·atm/(K·mol)),
  • \( T \) is the temperature in Kelvin.

First, we need to convert the given mass of chlorine gas (Cl₂) to moles:

  1. Calculate the molar mass of Cl₂:
  • The atomic mass of chlorine (Cl) is approximately 35.45 g/mol.
  • Therefore, the molar mass of Cl₂ = \( 2 \times 35.45 \Rightarrow 70.90 \) g/mol.
  1. Calculate the number of moles (\( n \)): \[ n = \frac{\text{mass}}{\text{molar mass}} = \frac{709 \text{ g}}{70.90 \text{ g/mol}} \approx 10.01 \text{ moles} \]

  2. Convert the temperature from Celsius to Kelvin: \[ T(K) = 35.0 + 273.15 = 308.15 \text{ K} \]

  3. Now, we can rearrange the Ideal Gas Law to solve for pressure \( P \): \[ P = \frac{nRT}{V} \]

  4. Substitute the values into the equation:

  • \( n = 10.01 \) moles,
  • \( R = 0.0821 \text{ L·atm/(K·mol)} \),
  • \( T = 308.15 \text{ K} \),
  • \( V = 12.0 \text{ L} \).

\[ P = \frac{(10.01 \text{ mol}) \times (0.0821 \text{ L·atm/(K·mol)}) \times (308.15 \text{ K})}{12.0 \text{ L}} \]

Calculating \( P \):

\[ P = \frac{(10.01) \times (0.0821) \times (308.15)}{12.0} \]

Calculating the numerator:

\[ = 10.01 \times 0.0821 \times 308.15 \approx 248.42 \]

Now, divide by 12.0 L:

\[ P \approx \frac{248.42}{12.0} \approx 20.70 \text{ atm} \]

Therefore, the pressure in the container is approximately 21.1 atm.

So the correct answer from the options provided is 21.1 atm.