Question

Calcium chloride is used to melt ice and snow on roads and sidewalks and to remove water from organic liquids. What is the molarity of a solution prepared by diluting 165 mL of 0.688 M calcium chloride to 925 mL?

Answer 1

We use the quotient....`"Concentration"="Moles of solute"/"Volume of solution"`

Explanation:

We take a `165*mL` volume of `0.688*mol*L^-1` `CaCl_2`, and then dilute this volume to `925*mL`...

And so `"Concentration"=(165xx10^-3*Lxx0.688*mol*L^-1)/(925*mLxx10^-3*L*mL^-1)`

`=(0.114*mol)/(0.925*L)=0.123*mol*L^-1`....

Note that the quotient defining concentration is fundamental; given 2 values we can find the third by multiplication or division. Of course in serial dilutions, we must keep track of what we have done....

I have written before here that the use of calcium chloride and sodium chloride (so-called `"grit-salt"`) on icy North American roads is one reason why there are so many rust buckets driving about in the States and Canada....salt splashed on the chassis greatly accelerates corrosion.