Molarity question 3 I want details explanation thx!

2006-12-25 10:38 pm

A commercial ammonia called "0.68ammonia "has a density of 0.68gcm^-3 and contains approximately 34% of ammonia by mass.
a)Calculate the mass of ammonia present in 1dm^3 of the solution of this commercial ammonia.
b)Calculate the molarity of this solution.
c)Calculate the volume of distilled water added if the solution has to be diluted to 1mol dm^-3.

回答 (1)

用戶4366

2006-12-25 11:45 pm

✔ 最佳答案

a)Calculate the mass of ammonia present in 1dm^3 of the solution of this commercial ammonia.
mass of 1 cm3 sample = 0.68 g
mass of NH3 in 1 cm3 sample = 0.68 X (34/100) = 0.2312 g
mass of NH3 in 1dm3 [1000 cm3] = 0.2312X1000 = 231.2 g
b)Calculate the molarity of this solution.
no. of mole of NH3 = 231.2 / (1X3 + 14) = 231.2 / 17 = 13.60 M
c)Calculate the volume of distilled water added if the solution has to be diluted to 1mol dm-3.
Assume 1 dm3 of 13.6 M solution at first; there are 13.6 mole NH3. If the final volume is V. It must has 1.00 = 13.6 / V. Therefore, V = 13.6 dm3. The volume of water to be added = 12.6 dm3.

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