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A mixture of KCl and KNO3 is 44.20% potassium by mass. The percent of KCl in the mixture is closest to

User Murmansk
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Explanation:

Assuming a basis of 100 grams

composition of Potassium = 44.2%

composition of potassium = 0.442

mass of potassium = 0.442 x 100g

Mass of potassium= 44.2 grams

mole of potassium = reacting mass / molar mass

Molar mass of potassium = 39.1 gram/ mol

Mole of potassium = 44.2 / 39.1

Mole of potassium = 1.13 moles

mole of potassium chloride + mole of potassium nitrate = mole of potassium

n(KCL) + n(KNO3) = n(k)

since mole (n) = m/M.M

Then we have,

m(KCL)/M.M(KCL) + m(KNO3)/M.M (KNO3) = 1.13

M.M (KCL) = 39.1 + 35.5

M.M (KCL) = 74.6 gram/mol

M.M (KNO3) = 39.1 + 14 + 3(16)

M.M (KNO3) = 39.1 + 14 + 48

M.M (KNO3) = 101.1 gram/mol

Let the mass of KCL be x

Let the mass of KNO3 be y

Assuming the total mass of the mixture is 100g

x + y = 100 ---------- equation 1

x/74.6 + y/101.1 = 1.13 ---- equation 2

From the first equation, make x the subject of the formula

x = 100 - y

100- y / 74.6 + y/101.1 = 1.1.3

1.355(100 - y) + y = 1.13 * 101.1

135.52 - 1.355y + y = 114.243

Collect the like terms

-1.355y - y = 114.243 - 135.52

-0.355y = -21.277

Divide both sides by -0.355

-0.355y/-0.355 = -21.277/-0.355

y = 59.9grams

y is 60 grams approximately

Recall, y is the mass of KNO3

From the first equation

x + y = 100

User Codr
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