Question

В стакан налили 150 г аммиачной воды (25%-й раствор аммиака в воде). Через некоторое время объем испарившегося аммиака составил 8,96 л. Вычислите,на сколько понизилась массовая доля аммиака в растворе

Answer 1

M(NH3)=150*0,25=37,5;
m(NH3)=(8,96/22,4)*17=6,8г-испарилось;
W(NH3)=(37,5-6,8)/(150-6,8)=30,7/143,2=0,2144(21,44%)
         25%-21,44%=на 3,56% понизилась.

Answer 2

Calculation of the Decrease in Ammonia Concentration

To calculate the decrease in the mass fraction of ammonia in the solution, we need to determine the initial mass of ammonia and the final mass of ammonia after evaporation.

Given: - Initial volume of the solution: 150 g - Concentration of ammonia in the solution: 25% (25 g of ammonia in 100 g of solution) - Volume of evaporated ammonia: 8.96 L

First, let's calculate the initial mass of ammonia in the solution: - Initial mass of the solution = Initial volume of the solution * Density of the solution - Density of the solution = Mass of the solution / Volume of the solution - Mass of the solution = Initial volume of the solution

Since the density of the solution is not provided, we will assume it to be the density of water, which is approximately 1 g/mL.

Therefore, the initial mass of the solution is 150 g.

Next, let's calculate the initial mass of ammonia in the solution: - Initial mass of ammonia = Initial mass of the solution * Concentration of ammonia - Concentration of ammonia = 25% = 0.25

Therefore, the initial mass of ammonia in the solution is 150 g * 0.25 = 37.5 g.

Now, let's calculate the final mass of ammonia in the solution: - Final mass of ammonia = Initial mass of ammonia - Mass of evaporated ammonia

Therefore, the final mass of ammonia in the solution is 37.5 g - 8.96 L = 28.54 g.

Finally, let's calculate the decrease in the mass fraction of ammonia in the solution: - Decrease in mass fraction of ammonia = (Initial mass of ammonia - Final mass of ammonia) / Initial mass of the solution * 100%

Therefore, the decrease in the mass fraction of ammonia in the solution is ((37.5 g - 28.54 g) / 150 g) * 100% = 5.97%.

The mass fraction of ammonia in the solution decreased by approximately 5.97%.