Which solution has the same number of moles of KCl as 75.00 mL of 0.250 M solution of KCl?
A)20.0 mL of 0.200 M solution of KCl
B)25.0 mL of 0.175 M solution of KCl
C)129 mL of 0.145 M solution of KCl
D)50.0 mL of 0.125 M solution of KCl
E)100 mL of 0.0500 M solution of KCl

Question

Quizplus · Accepted Answer

We can use the formula:

moles of solute = concentration x volume

to calculate the number of moles of KCl in 75.00 mL of 0.250 M solution:

moles of KCl = 0.250 mol/L x 0.07500 L = 0.01875 mol

Now we need to find a solution that also contains 0.01875 mol of KCl. We can use the same formula to solve for the volume of each solution:

A) 0.200 mol/L x 0.0200 L = 0.004 mol 
B) 0.175 mol/L x 0.0250 L = 0.0044 mol 
C) 0.145 mol/L x 0.129 L = 0.0187 mol 
D) 0.125 mol/L x 0.0500 L = 0.00625 mol 
E) 0.0500 mol/L x 0.100 L = 0.005 mol

Option C has the closest number of moles to 0.01875 mol, so it is the best choice.

Which Solution Has the Same Number of Moles of KCl