the concentration is inversely proportional to the volume
30 / 400 = c / 15.8 M
What is the concentration of a solution obtained by diluting 30 mL of 15.8 M hydrochloric acid so the total volume of the solution will be 400mL
2 answers
Also, there is a dilution formula that can be used.
mLa x Ma = mLb x Mb
30 x 15.8 = 400 x M
Solve for M.
Finally, a different play on what R_Scott wrote.
When you dilute a solution you KNOW it will get weaker, so start with the 15.8 and use a fraction arranged to get a smaller number like this.
15.8 x (30/400) = ?.You know to put the 30 on top and the 400 on the bottom because that's the only way you can get a smaller number. If you used 15.8 x (400/30) you will get a larger number and you know that can't be right.
mLa x Ma = mLb x Mb
30 x 15.8 = 400 x M
Solve for M.
Finally, a different play on what R_Scott wrote.
When you dilute a solution you KNOW it will get weaker, so start with the 15.8 and use a fraction arranged to get a smaller number like this.
15.8 x (30/400) = ?.You know to put the 30 on top and the 400 on the bottom because that's the only way you can get a smaller number. If you used 15.8 x (400/30) you will get a larger number and you know that can't be right.
5 answers