Question

a) Calculate the mass of potassium chloride required to prepare its 40% solution in 250gm of water. ​

Answer 1

We have the following data:

% m / m (mass percentage of solute per mass of solution) = 40

m1 (solute mass) =? (in grams)

m2 (mass of the solvent) = 100 g

m (mass of solution)

It is known that the mass of solution is equal to the sum of the mass of the solute (m1) with the mass of the solvent (m2)  

We apply the data to the formula of the mass percentage of solute per mass of solution, see:

\%\:m/m = \dfrac{m_1}{m}*100%m/m=mm1∗100

\%\:m/m = \dfrac{m_1}{m_1+m_2}*100%m/m=m1+m2m1∗100

40 = \dfrac{m_1}{m_1+100}*10040=m1+100m1∗100

40*(m_1+100) = m_1*10040∗(m1+100)=m1∗100

40\:m_1 + 4000 = 100\:m_140m1+4000=100m1

4000 = 100\:m_1 - 40\:m_14000=100m1−40m1

4000 = 60\:m_14000=60m1

60\:m_1 = 400060m1=4000

m_1 = \dfrac{400\diagup\!\!\!\!0}{6\diagup\!\!\!\!0}m1=6╱0400╱0

ans is 400/6

Answer 2

Given: The given data is 40% solution in 250gm of water.

To find: We have to find the mass of solute potassium chloride.

Solution:

We know that mass percent is a ratio of mass of solute to mass of solution multiplied by 100.

Here mass of solvent water is n=250 gram.

Mass percentage is 40%.

Let mass of solute potassium chloride is m gram.

So, mass of the solute potassium chloride will be-

$m\% = \frac{m}{m + n} \times 100 \\ 40 = \frac{m}{m + 250} \times 100 \\ 40m + 10000 = 100m \\ 60m = 10000 \\ m = 166.66$

The value of m is 166.66 gram.

The mass of potassium chloride is 166.66 gram.