30. A5.30 g of Na2CO3 is dissolved in a 400.0 mL solution. What is the molarity for this solution? A. 0.0133 M
B. 0.0500 M
C. 0.125 M
D. 13.3 M

We first compute for the moles, n, of the solute sodium carbonate,
N
a
2
C
O
3
, by converting the given 5.30 g of the solute using its molar mass, 105.99 g/mol:

n
=
5.30

g

N
a
2
C
O
3
×
1

m
o
l

N
a
2
C
O
3
105.99

g

N
a
2
C
O
3
=
0.0500

m
o
l

N
a
2
C
O
3