Question

К 300 г 80 % раствора этанола долили 700 г воды. Вычислить массовую долю спирта в новом растворе. Варианты ответа: а) 1,2 % б) 2,4 % в) 4,8 % г) 20,8 % РЕШЕНИЕ ОБЯЗАТЕЛЬНО.Помогите пожайлуста)))

Answer 1

M спирта в растворе = 300 г * 0,8= 240г
m раствора = 300 + 700 = 1000 г 
ω спирта = 240г / 1000г * 100% = 2.4 %
Ответ: Б 

Answer 2

Calculation of the Mass Fraction of Alcohol in the New Solution

To calculate the mass fraction of alcohol in the new solution, we need to consider the initial solution and the amount of water added.

Given: - Initial solution: 300 g of 80% ethanol solution - Water added: 700 g

To solve this problem, we can use the formula for calculating the mass fraction:

Mass Fraction = (Mass of Alcohol) / (Total Mass of Solution)

Let's calculate the mass of alcohol in the initial solution:

Mass of Alcohol in the Initial Solution = (80% of 300 g) = 0.8 * 300 g = 240 g

Next, let's calculate the total mass of the new solution:

Total Mass of the New Solution = Mass of Alcohol in the Initial Solution + Mass of Water Added

Total Mass of the New Solution = 240 g + 700 g = 940 g

Now, we can calculate the mass fraction of alcohol in the new solution:

Mass Fraction of Alcohol in the New Solution = (Mass of Alcohol in the Initial Solution) / (Total Mass of the New Solution)

Mass Fraction of Alcohol in the New Solution = 240 g / 940 g ≈ 0.2553

Therefore, the mass fraction of alcohol in the new solution is approximately 25.53%.

Please note that the answer options provided in the question do not match the calculated result.