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4 years ago

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A solution was prepared by dissolving 40.0 g of kcl in 225 g of water. part a calculate the mass percent of kcl in the solution.

express your answer with the appropriate units. 15.1 {\rm \\%} calculate the mole fraction of the ionic species kcl in the solution.

2 answers:

EleoNora [17]4 years ago

6 0

<h2> part A : </h2><h2>The mass % of KCl = 17.78 %</h2>

<u>calculation </u>

mass%= mass of the solute/mass of the solvent x100

mass of the solute 40 g

mass of the solvent=225

% mass= 40/225 x100=17.78%

<h2>Part B</h2><h3>The mole fraction of ionic species =0.04296</h3>

the mole fraction=moles of KCl/ moles of the solution

moles of KCl= 40 g/74.5 g/mol=0.537 moles

moles of water = 225g/18 g/mol=12.5 moles

mole fraction is therefore= 0.537/12.5=0.04296

Alex4 years ago

3 0

Explanation:

(a) According to the given data, mass of the solution will be calculated as follows.

Mass of solution = Mass of KCl + Mass of water

= (40 + 225) g

= 265 g

Therefore, (m/m)% of KCl will be calculated as follows.

(m/m)% of KCl = $\frac{\text{mass of KCl}}{\text{mass of solution}} \times 100$

= $\frac{40}{265} \times 100$

= 15.09%

Hence, mass percent of KCl in the solution is 15.09%.

(b) Now, we will calculate the mole fraction of ionic species present in KCl in the solution are follows.

Molar mass of KCl is 74.55 g/mol.

Moles of KCl = $\frac{mass}{\text{molar mass}}$

= $\frac{40 g}{74.55 g/mol}$

= 0.536 mol

or, = 0.54 mol

As, molar mass of water is 18 g/mol. Hence, moles of water will be calculated as follows.

Moles of $H_{2}O$ = $\frac{mass}{\text{molar mass}}$

= $\frac{225 g}{18 g/mol}$

= 12.5 mol

So, total number of moles = moles of KCl + moles of $H_{2}O$

= (0.54 + 12.5) mol

= 13.04 mol

Calculate the mole fraction of KCl in the solution as follows.

Mole fraction = $\frac{\text{moles of KCl}}{\text{total moles}}$

= $\frac{0.54 mol}{13.04 mol}$

= 0.041

Therefore, mole fraction of the ionic species KCl in the solution is 0.041.

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