GATE 2023 CH – Question 49

Process Calculations · Steady and unsteady state mass and energy balances · 2 marks · Numerical answer

Wet air containing 10 mole percent water vapor is dried by continuously passing it through a column of CaCl$_2$ pellets. The pellets remove 50 percent of water from wet air entering the column. The mole percent of water vapor in the product stream exiting the column is ___________ (rounded off to two decimal places).

Practise this question in The GATE Grind →

Show answer and explanation

Correct answer: 5.23 to 5.29

Explanation

Take 100 mol of wet air: 10 mol water and 90 mol dry air. Half of the water, 5 mol, is removed, leaving 5 mol of water in $90 + 5 = 95$ mol. The mole percent is $\frac{5}{95} \times 100 = 5.26\%$.