Question

A gas has a pressure of 730 kPa at 96°C. What will the pressure be at 45°C?

Answer 1

Answer:

630 kPa

Explanation:

Given data

• Initial pressure (P₁): 730 kPa

• Initial temperature (T₁): 96 °C

• Final pressure (P₂): ?

• Final temperature (T₂): 45 °C

Step 1: Convert the temperatures to the absolute scale (Kelvin)

When working with gases, we always need to convert the temperatures to the Kelvin scale. We will use the following expression.

K = °C + 273.15

T₁: K = 96 °C + 273.15 = 369 K

T₂ = K = 45 °C + 273.15 = 318 K

Step 2: Calculate the final pressure

We will use Gay-Lussac's law.

$P_1 \times T_2 = P_2 \times T_1\\P_2 = \frac{P_1 \times T_2}{T_1} = \frac{730kPa \times 318K}{369K} = 630 kPa$