Question

A mineral water sample was analysed and found to contain 1 × 10–3 % ammonia (w/w). The mole of dissolved ammonia gas in one litre water bottle is (dwater 1 gm/ml)

• A. 5.8 ×10–4mol
• B. 1 × 10–2mol
• C. 0.58 ×10–2mol
• D. same as w/w

Answer 1

(1)

10–3 g NH3 in 100 g solution

one litre water has mass = 1000 ´ 1 g

As NH3 is very less hence we can say

100 g water has 10–3 g NH3

$\therefore$1000 gm water has = $\frac{10^{- 3}}{17}$ ´ 1000 g

= 10–2 g NH3 = $\frac{10^{- 2}}{17}$ mole NH3 = 5.88 ´ 10–4 mole NH3.