Chemistry 2005 JAMB Past Questions - Question 33: The pressure of 100cm³ of oxygen at 35°C is 750mmHg. What will be the volume of the gas if the pressure is reduced to 100mmHg without changing the temperature?

Correct Answer

D

Explanation

Boyle's law P1 V1 = P2 V2To solve this problem, we can use Boyle's Law, which states that the pressure of a given amount of gas is inversely proportional to its volume when the temperature is held constant. Mathematically, Boyle's Law is expressed as:

\[ P_1 \cdot V_1 = P_2 \cdot V_2 \]

Where:
- \( P_1 \) is the initial pressure,
- \( V_1 \) is the initial volume,
- \( P_2 \) is the final pressure,
- \( V_2 \) is the final volume.

In this case, the initial pressure \( P_1 \) is 750 mmHg, the initial volume \( V_1 \) is 100 cm³, and the final pressure \( P_2 \) is 100 mmHg. We need to find the final volume \( V_2 \).

\[ (750 \, \text{mmHg}) \cdot (100 \, \text{cm³}) = (100 \, \text{mmHg}) \cdot V_2 \]

Now, solve for \( V_2 \):

\[ V_2 = \frac{(750 \, \text{mmHg}) \cdot (100 \, \text{cm³})}{100 \, \text{mmHg}} \]

\[ V_2 = 75000 \, \text{cm³} \]

So, the volume of the gas will be 75000 cm³ when the pressure is reduced to 100 mmHg without changing the temperature.