You dissolve 0.74 g of potassium chloride in 500 mL of water. What is the molarity of the solution?

1 Answer
anor277
May 23, 2017

#"Molarity"="Moles of solute"/"Volume of solution (L)"=0.02*mol*L^-1#.

Explanation:

#"Molarity"=((0.74*cancelg)/(74.55*cancelg*mol^-1))/(500*cancel(mL)xx10^-3*L*cancel(mL^-1))=??*mol*L^-1#.

I include the units, even tho it is a bit a pfaff, to ensure that I have done the right order of operation. It is all too easy to divide when we should have multiplied, and vice versa. We want an answer with units of concentration, i.e. #mol*L^-1#, and we got one!

Remember #1/(mol^-1)=1/(1/(mol))=mol# as required.............

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