What is the final concentration of a solution if 15-mL of a 2.4-M solution was diluted to 100-mL and this process was repeated two more times?

Please help me how to work out the problem. I am not just looking for an answer. I really want to learn.

1 answer

If you want a formula for dilution it is mL1 x M1 = mL2 x M2
For example 15 x 2.4 = 100 x M2 and you solve for M2. Then you repeat that two more times to arrive at the final answer. For problems like this; however, I think it is easier to run each dilution like this. You know the new concn will be 2.4M x a factor.
2.4 x (15/100 = ? but all of this can be run together like this
2.4 x (15/100) x (15/100) x (15/100) = ? Voila