Question

The solubility of NH3 gas in water at an NH3pressure of 760.0 mmHg and 25 ∘C is 51.8 g/100mL and 27.0 g/100mL at 50 ∘C.

How many moles of NH3 would be released from 3.5 L of a saturated NH3 solution if the temperature was increased from 25 to 50 ∘C?

Answer 1

At 25 oC,

solubility = 51.8 g/100 mL

In 3.5 L,

mass of NH3 = 3.5 L * 51.8 g/100 mL

= 3500 mL * 51.8 g/100 mL

= 1813 g

At 50 oC,

solubility = 27.0 g/100 mL

In 3.5 L,

mass of NH3 = 3.5 L * 27.0 g/100 mL

= 3500 mL * 27.0 g/100 mL

= 945 g

mass of NH3 released = 1813 g - 945 g

= 868 g

Molar mass of NH3,

MM = 1*MM(N) + 3*MM(H)

= 1*14.01 + 3*1.008

= 17.034 g/mol

mass(NH3)= 868 g

use:

number of mol of NH3,

n = mass of NH3/molar mass of NH3

=(8.68*10^2 g)/(17.03 g/mol)

= 50.96 mol

Answer: 51.0 mol