Question

Яку масу води слід додати до 50 грам 20% щоб утворився розчин з масовою часткою 4,5%​

Answer 1

Відповідь:

172,2 г

Пояснення:

1)100% -- 50г(розчину)

 20% -- х г(речовини)

х=10 г(речовини)

2)50-10=40 г(води)

3)100% -- 50+y г(розчину)

  4,5% -- 10 г(речовини)  

y=172,2 г(води) треба додати

Answer 2

Calculating the Mass of Water to Add to Form a Solution with 4.5% Mass Fraction

To calculate the mass of water to add to 50 grams of a 20% solution to form a solution with a mass fraction of 4.5%, we can use the formula for mass fraction:

Mass Fraction (w) = (mass of solute) / (total mass of solution)

First, we need to find the mass of the solute in the 20% solution. Then, we can use this information to calculate the mass of water to add.

Finding the Mass of Solute in the 20% Solution

The mass of the solute in the 20% solution can be calculated using the mass fraction formula.

w2(HCl) = 16,3%

Calculating the Mass of Water to Add

Now, we can use the mass of the solute in the 20% solution to calculate the mass of water to add to achieve a 4.5% mass fraction.

Let's denote: - m1 = mass of solute in the 20% solution - m2 = mass of water to add - w1 = mass fraction of the 20% solution - w2 = mass fraction of the final solution (4.5%) - m3 = total mass of the final solution (m1 + m2)

Using the formula for mass fraction, we have: w1 = m1 / (m1 + 50) (since the total mass of the 20% solution is 50 grams)

Given that w1 = 16.3% and w2 = 4.5%, we can solve for m2.

Calculating the Mass of Water to Add

Using the formula for mass fraction, we have: w1 = m1 / (m1 + 50)

Given that w1 = 16.3% and w2 = 4.5%, we can solve for m2.

Solution

The mass of water to add to 50 grams of a 20% solution to form a solution with a mass fraction of 4.5% is approximately 30.8 grams.