Calculate the molar concentration of sodium carbonate in the solution if 400 ml of water was added

| February 19, 2021 | education

Calculate the molar concentration of sodium carbonate in the solution if 400 ml of water was added to 2 liters of a 10% solution of this salt with a solution density of 1.1 g / ml.

Given:
V solution (Na2CO3) = 2 l
ω (Na2CO3) = 10%
ρ solution (Na2CO3) = 1.1 g / ml
V (H2O) = 400 ml

To find:
C (Na2CO3) -?

Decision:
1) find the mass of the initial Na2CO3 solution:
m solution (Na2CO3) = V solution (Na2CO3) * ρ solution (Na2CO3) = 2000 * 1.1 = 2200 g

2) find the mass of dry matter Na2CO3:
m (Na2CO3) = m solution (Na2CO3) * ω (Na2CO3) / 100% = 2200 * 10% / 100% = 220 g

3) find the amount of substance Na2CO3:
n (Na2CO3) = m (Na2CO3) / Mr (Na2CO3) = 220/106 = 2.08 mol

4) find the volume of the final Na2CO3 solution:
V final solution (Na2CO3) = V initial solution (Na2CO3) + V (H2O) = 2 + 0.4 = 2.4 l

5) find the molar concentration of Na2CO3:
C (Na2CO3) = n (Na2CO3) / V solution (Na2CO3) = 2.08 / 2.4 = 0.87 mol / l

Answer: The molar concentration of sodium carbonate (Na2CO3) in the solution is 0.87 mol / l.



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