How does dilution affect molarity?

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Answer 1 · 2014-04-25T15:38:27

Diluting a sample will reduce the molarity.

For example if you have 5mL of a 2M solution which is diluted to a new volume of 10mL the molarity will be reduced to 1M.

To solve a problem like this one you'll apply the equation:
$M_{1} V_{1}$ $M_1V_1$ = $M_{2} V_{2}$ $M_2V_2$

This would be solved to find
$M_{2}$ $M_2$ = ( $M_{1} V_{1}$ $M_1V_1$ )/ $V_{2}$ $V_2$

$M_{2}$ $M_2$ = (5mL*2M)/10mL

Here is a video that describes this process and provides another example of how to calculate the change in molarity when a solution is diluted.