Question

At standard pressure (760 mm) water boils at 100C. A vacuum pump is used to reduce the ambient pressure above water under a sealed bell jar. By reducing the pressure, the boiling point is lowered so that the water begins to boil at room temperature. What is the approximate pressure at which water boils at room temperature (22C)?

Answer 1

Answer:

601mmHg.

Explanation:

Step 1:

Data obtained from the question.

Initial pressure (P1) = 760mmHg

Initial temperature (T1) = 100°C = 100°C + 273 = 373K

Final temperature (T2) = 22°C = 22°C + 273 = 295K

Final pressure (P2) =..?

Step 2:

Determination of the new pressure at which the water will boil.

The new pressure on the at which the water will boil can be obtained as follow:

P1/T1 = P2/T2

760/373 = P2/295

Cross multiply to express in linear form

373 x P2 = 760 x 295

Divide both side by 373

P2 = (760 x 295) / 373

P2 = 601mmHg

Therefore, the new pressure at which the water will boil is approximately 601mmHg.

Answer 2

Answer:

C. 18-20 mm

Explanation: