Calculate the molarity of 90.0 mL of a solution that is 0.92 % by mass NaCl. Assume the density of the solution is the same as pure water.

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Chemistry

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13 August, 18:30

Calculate the molarity of 90.0 mL of a solution that is 0.92 % by mass NaCl. Assume the density of the solution is the same as pure water.

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Tanya · Answer 1

Answer is: molarity is 0,155 M.

V (solution) = 90,0 mL = 0,09 L.

ω (NaCl) = 0,92% : 100% = 0,0092.

d (solution) = 1 g/mL.

m (solution) = V (solution) · d (solution).

m (solution) = 90 mL · 1 g/mL = 90 g.

m (NaCl) = 90 g · 0,0092 = 0,828 g.

n (NaCl) = 0,828 g : 58,4 g/mol.

n (NaCl) = 0,014 mol.

c (solution) = 0,014 mol : 0,09 L.

c (solution) = 0,155 mol/L.