A solutIon made by dissolving 16.0g of CaCl2 in 64.0g of water has a density of 1.180g/mL at 20° C, see details for the questions?

a. What is the percent by mass of CaCl2 in the solution.
b. What is the molarity of CaCl2 in the solution.
Ca= 40.08
Cl= 35.45
Na=22.99
H=1.01
C=12.01
O=16.00
S=32.07

1 Answer
anor277
Jan 28, 2018

Well we first address the volume of the solution....

Explanation:

Normally, when we make a solution, the volume of the solution is unchanged with respect to the volume of the solvent used...here we uses a #64.0*g# mass of water...let us address the volume...

The solution has a mass of #80.0*g# mass. Why?

And so #"volume"="mass"/rho_"solution"=(80.0*g)/(1.180*g*mL^-1)#

#=67.80*mL#

And so ...........

#"Percentage by mass"="Mass of solute"/"Mass of solution"=(16*g)/(80.0*g)xx100%=20%#

#"Concentration"="moles of solute"/"volume of solution"#

#=((16.0*g)/(110.98*g*mol^-1))/(67.8xx10^-3*L)~=2.0*mol*L^-1#

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