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CHEMISTRY, M2 2013 VCE 1 MC

Consider the following.

"Calculate the pressure exerted by 6.9 g of argon in a 0.07500 L container at 11.5 °C."

The number of significant figures that should be expressed in the answer is

  1. 2
  2. 3
  3. 4
  4. 5
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\(A\)

Show Worked Solution
  • The data input for calculating the pressure with the least number of significant figures is 6.9 grams (to 2 sig fig).
  • The answer should then be expressed to 2 significant figures.

\(\Rightarrow A\)

CHEMISTRY, M2 2014 VCE 9*

An aerosol can with a volume of 300.0 mL contains 2.80 g of propane gas as a propellant. The warning label says the aerosol may explode at temperatures above 60.0 °C.

What is the pressure in the can at a temperature of 60.0 °C?   (2 marks)

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\(5.87 \times 10^{2}\ \text{kPa}\)

Show Worked Solution

\(\ce{MM(C3H8) = 3 \times 12.0 + 8 \times 1.0 = 44.0\ \text{g mol}^{-1}} \)

\(\ce{n(C3H8) = \dfrac{2.80}{44.0} = 0.0636\ \text{mol}} \)

\(\ce{n(C3H8)}\) \( = \dfrac{pV}{RT} \)  
\(p(\ce{C3H8}) \) \(= \dfrac{nRT}{V} \)  
  \(=0.0636 \times 8.31 \times \dfrac{(60.0 + 273)}{300.0 \times 10^{-3}} \)  
  \(=5.87 \times 10^2\ \text{kPa} \)