Question

calculate the mass of potassium chloride required to prepare its 40 per cent solution in 100 gm of water

Answer 1

Hello!  

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:

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

$\%\:m/m = \dfrac{m_1}{m_1+m_2}*100$

$40 = \dfrac{m_1}{m_1+100}*100$

$40*(m_1+100) = m_1*100$

$40\:m_1 + 4000 = 100\:m_1$

$4000 = 100\:m_1 - 40\:m_1$

$4000 = 60\:m_1$

$60\:m_1 = 4000$

$m_1 = \dfrac{400\diagup\!\!\!\!0}{6\diagup\!\!\!\!0}$

$\boxed{\boxed{m_1 \approx 66.6\:grams\:of\:potassium\:chloride}}\Longleftarrow(solute\:mass)\end{array}}\qquad\checkmark$

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I Hope this helps, greetings ... Dexteright02! =)

Answer 2

Answer:

66.66g

Explanation:

let the mass of potassiun chloride required be xg

The mass of solution is (x+100)g of solution

40℅=x÷x+100×100

40x+4000=100x

60x=4000

x=4000÷60=66.66g answer