Quiz 3
Chem 1303.001
General Chemistry
Fall 2018
KEY
(35 pts)
a.
How many mL of a 5.00 M H
2
SO
4
stock solution are needed to prepare 100 mL of a 0.300 M H
2
SO
4
solution?
M
1
V
1
= M
2
V
2
V
1
= M
2
V
2
/M
1
0.300 M
100 mL
=
6.00 mL
5.00 M
Or mol H
2
SO
4
needed:
0.100 L
0.300 mol
=
0.0300 mol
1 L
mL stock solution needed:
0.0300 mol
1 L
=
0.00600 L
=
6.00 mL
5.00 mol
For the 0.400 M H
2
SO
4
solution
M
1
V
1
= M
2
V
2
V
1
= M
2
V
2
/M
1
0.400 M
100 mL
=
8.00 mL
5.00 M
Or mol H
2
SO
4
needed:
0.100 L
0.400 mol
=
0.0400 mol
1 L
mL stock solution needed:
0.0400 mol
1 L
=
0.00800 L
=
8.00 mL
5.00 mol
b.
describe the preparation of the above solution using a 100-mL volumetric flask.
Add 6.00 mL of the stock solution to the volumetric flask.
Add some water.
Mix well.
Dilute to mark, cap, and invert several times to mix thoroughly.
In this case, you can skip the two intermediate steps, since there is no solid to dissolve.
c.
How many mL of 0.150 M KOH are needed to completely neutralize 23.0 mL of the above 0.300 M H
2
SO
4
?
H
2
SO
4
+
2 KOH
à
K
2
SO
4
+
2 H
2
O
0.0230 L H
2
SO
4
0.300 mol H
2
SO
4
2 mol KOH
1 L KOH
= 0.0920 L KOH = 92.0 mL KOH
1 L H
2
SO
4
1 mol H
2
SO
4
0.150 mol KOH

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- Chemistry, Redox, mol KOH, M H2SO4 stock solution