Answer:
For starters, convert the mass of potassium bromide to moles by using the molar mass of the compound.
15.6
g
⋅
1 mole KBr
119.002
g
=
0.1311 moles KBr
Now, in order to find the molarity of the solution, you need to figure out how many moles of solute are present for every
1 L
of solution.
You already know that
1.25 L
of solution contain
0.1311
moles of potassium bromide, the solute, so all you have to do now is to use this known composition as a conversion factor to go from
1 L
of solution to number of moles of solute.
1
L solution
⋅
0.1311 moles
1.25
L solution
=
0.10488 moles KBr
Since this represents the number of moles of solute present in
1 L
of solution, you can say that the molarity of the solution is equal to
molarity = 0.105 mol L
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