Chemistry Help?

Question

http://www.bi10etc.com/reaction-rates.pdf

Why was it necessary in all the kinteic runs to keep constant the total volume of the reagents after mixing, (that is, why was it necessary to add distilled water in inverse proportion to the quantity of Soultion 1 that was required)?

Answer 1

Step 1:

From the table of Kinetic runs:

Run	mL Solution 1	mL Distilled water	mL Solution 2
A	10.0	80.0	10.0
B	20.0	70.0	10.0
C	30.0	60.0	10.0
D	40.0	50.0	10.0
E	50.0	40.0	10.0

The molarity of solution depends on two factors: the amount of reactant present and the total volume that it is dissolved in. 

The rate depends on concentration of reactants.

Changing the volume would change the concentration making the determination of rate inaccurate.

If you add the distilled water, the total volume would not change, thus keeping the concentration of reactant constant.

Solution:

Adding distilled water would make the concentration of reactant constant, making rate of reaction accurate.