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Reika [66]
2 years ago
9

Dissolving 5.28 g of an impure sample of calcium carbonate in hydrochloric acid produced 1.14 l of carbon dioxide at 20.0 °c an

d 791 mmhg. Calculate the percent by mass of calcium carbonate in the sample.
Chemistry
1 answer:
kvv77 [185]2 years ago
8 0

Answer:

Percentage by mass of calcium carbonate in the sample is 93.58%.

Explanation:

Assumptions:

  • calcium carbonate was dissolved completely and the amount of carbon dioxide released was proportional to the amount of calcium carbonate.
  • the sample did not contain any other compound that released or reacted with carbon dioxide.

PV = nRT

n = \frac{PV}{RT}

P = 791 mmHg = \frac{791 mmHg}{760 mmHg} x 1 atm = 1.040789 atm.

R = 8.314 \frac{J}{K*mol} = 0.082 \frac{L*atm}{K*mol}

T = 20^{0}C + 273^{0} C = 293 K

n = \frac{1.040789 atm * 1.14 L}{0.082 \frac{L * atm}{K * mol} * 293 K }

n = 0.0493839 mol.

given the equation of the reaction:

CaCO_{3}  + 2HCL =  CaCl_{2}  + CO_{2} + H_{2}O

from assumption:

amount carbon dioxide = amount of calcium carbonate

n(CaCO_{3} ) = n(CO_{2} )

reacting mass ( m )  = Molar Mass ( M ) * Amount ( n )

m(CaCO_{3} )   =   n(CaCO_{3} )  *   M(CaCO_{3} )

m = 0.04938397 mol * 100 \frac{g}{mol} =  4.93839 g

percentage by mass of   CaCO_{3} = \frac{mass of pure  }{mass of impure}*100  = \frac{4.93839g}{5.28g}*100  = 93.5802%.

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