Question

Даю 50 баллов Вычислите массовую долю вещества, если к 30г 5% раствора сахара добавить 20г воды

Answer 1

Дано:
mр-ра=30 г
wв-ва1=5%
m(H2O) = 20 г
-----------------
w-ва 2-?

Решение:
mв-ва=30г х 0.05=1.5 г

                         1.5 г                    1.5 г
wв-ва 2 =   --------------------  = --------------=0.03 или 3 %
                      30 г + 20г                50г
 
Ответ: wв-ва 2 = 3%

Если помог нажми кнопку Спасибо))

Answer 2

1) масса сахара в исходном растворе
5 г в 100г
x .... в 30г
x=5*30/100=1.5 г

Масса раствора после тогда как прилили 20 г будет 30+20= 50 г

w сахара = m сахара/ m раствора *100% = 1.5/50*100%= 3%

Ответ: массовая доля вещества после того как добавили 20г воды 3 %

Answer 3

Calculation of Mass Fraction

To calculate the mass fraction of a substance, we need to know the mass of the solute (substance being dissolved) and the total mass of the solution.

In this case, we have a 5% solution of sugar, which means that 5 grams of sugar are dissolved in 100 grams of solution. We are given 30 grams of this 5% sugar solution and we need to add 20 grams of water.

To calculate the mass fraction of sugar in the resulting solution, we can follow these steps:

1. Calculate the mass of sugar in the initial solution: - Mass of sugar = 5% of 30 grams = 0.05 * 30 grams = 1.5 grams

2. Calculate the total mass of the resulting solution: - Total mass of solution = mass of initial solution + mass of water - Total mass of solution = 30 grams + 20 grams = 50 grams

3. Calculate the mass fraction of sugar in the resulting solution: - Mass fraction of sugar = (mass of sugar / total mass of solution) * 100% - Mass fraction of sugar = (1.5 grams / 50 grams) * 100% = 3%

Therefore, the mass fraction of sugar in the resulting solution is 3%.

Please note that the calculation assumes that the volume of the solution remains constant when water is added.