The question asks for the amount of water that should be
added to the existing 400mL solution.

C1 = 0.1, C2 = 0.075, V1 = 0.4, V2= ?
(0.1 X 0.4) / 0.075 = 0.535
The final volume should be 535mL so the volume that must be added to 400mL
is 135mL

C_{1}V_{1} = C_{2}V_{2}

The question asks for the amount of water
that should be added to the existing 80mL solution.

C1 = 0.6, C2 = 0.07, V1 = 0.08, V2= ?
(0.6 X 0.08) / 0.07 = 0.668
The final volume should be 686mL so the volume that must be added to 80mL
is 606mL.

C_{1}V_{1} = C_{2}V_{2}

The question asks for the o.1MNaOH solution
after it has been diluted by the addition of 50 mL of water.

C1 = 0.1, C2 = ?, V1 = 0.23, V2= 0.28
(0.1 X 0.23) / 0.28 = 0..082
The final concentration is 0.082M

C_{1}V_{1} = C_{2}V_{2}

C1 = 0.5, C2 = ?, V1 = 1, V2= 3
(0.5 X 1) / 3 = 0.167
The final concentration is 0.167M

C_{1}V_{1} = C_{2}V_{2}

C1 = ?, C2 = 0.45, V1 = 1, V2= 7
C1 =(0.45 X 7) / 1 = 3.15
The original concentration is 3.15M

Dilution
Exercises

Try the following exercises.

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Exercise

Answer

What
volume of water should be added to 400ml of a 0.1M NaOH solution
in order to change the concentration to 0.075M NaOH.

What volume
of water should be added to 80ml of a 0.6M NaOH solution
in order to change the concentration to 0.07M NaOH.

50mls of
water are added to 230mls of a 0.1M NaOH solution. What is the concentration
of the solution ?

A 1 litre vessel containing
0.5M NaOH solution is connected to a 2 litre vessel containing
pure water via a valve (as shown above). When the valve is opened
the solute dissolves evenly in both vessels. A sample of water
is taken from the 2 litre vessel and analysed. What is the concentration
of the sample?

A 1 litre NaOH solution
is connected to a 6 litre vessel containing pure water via a valve
(as shown above). When the valve is opened the solute dissolves
evenly through both vessels. A sample of water is taken from the
6 litre vessel and analysed. If the concentration of the sample
was found to be 0.45M calculate the concentration of the original
solution in the 1 litre vessel?

What volume
of water should be added to 200ml of a 0.01M NaOH solution
in order to change the concentration to 0.0055M NaOH.
solution

What volume
of water should be added to 400ml of a 0.9M NaOH solution
in order to change the concentration to 0.075M NaOH.
solution