kennedy_meyer_
Posts: 3
Joined: Fri Sep 29, 2017 7:04 am

In the problem G.13, how do you determine that the concentration of the diluted NH4NO3 solution is .050 M?

704887365
Posts: 49
Joined: Sat Jul 22, 2017 3:00 am

You have to use MV=MV, using (1)(0.02)=(4)(M). This will give you the concentration as 0.05M.

Maria1E
Posts: 61
Joined: Sat Jul 22, 2017 3:01 am

You use a key concept that Dr. Lavelle outlined in his lecture on 10/2: When diluting a solution, moles of solute remain the same. Therefore, you can use the formula (M initial)(V initial) = (M final)(V final), where M is molarity and V is volume. For this problem, we are told that a florist dilutes 1 L of 0.20 M NH4NO3 by adding 3 L of water. You want to find the molarity of the diluted solution. The initial molarity is 0.20 M NH4NO3 and the initial volume is 1 L. Since you are adding 3 L of water to the original volume of 1, the final volume is 4 L. Then plug those factors into the equation I mentioned above. You will get:

(0.20 M NH4NO3)(1 L NH4NO3) = (? M)(4 L NH4NO3)
0.20 = (? M)(4)
?M = .20/4
= .050 M NH4NO3

Ashley Chipoletti 1I
Posts: 20
Joined: Fri Sep 29, 2017 7:04 am