How many milliters of water should be added to 25.0 mL of 12.0M HCl to make 5.00 M HCl ?
(Assume that the volumes are additive.)
Answers
Explanation:
Your strategy here will be to use the molarity and volume of the diluted solution to determine how many moles of solute, which in your case is hydrochloric acid,
HCl , it must contain..
Once you know this value, you an sue the molarity of the stock solution as a conversion factor to see how many milliliters would contain this many moles.
The underlying principle of a dilution is the fact that the number of moles of solute must remain constant. Basically, a dilution decreases the concentration of a solution by increasing its volume.
As you know, a solution's molarity tells you how many moles of solute you get per liter of solution. The diluted solution has a molarity of
3.00 mol L−1 , which means that every liter of this solution will contain 3.00moles of hydrochloric acid.
In your case, the 500.-ml sample will contain,
1.5 moles HCL
Now use the molarity of the stock solution to determine how many milliliters would contain 1.5 moles of HCl. Since a concentration of 12.0 molL−1means that you get 12.0 moles of hydrochloric acid per liter of solution you an say that you have,