You dissolve a 1.28-g sample of NaCl in a total volume of 125.0 mL of solution. Your lab partner has 1.50 M aqueous NaCl and wants to make a solution with the same concentration and volume as yours. How much of the solution does your lab partner need to use?
A) 1.83 mL
B) 14.6 mL
C) 125 mL
D) 107 mL
E) none of these

Question

Quizplus · Accepted Answer

First, we need to find the molarity of the solution we made:
Molarity = number of moles of solute / volume of solution
Since we dissolved 1.28 g of NaCl, we first need to convert that to moles:
1.28 g NaCl x (1 mol NaCl / 58.44 g NaCl) = 0.0219 mol NaCl
Now we can plug in the values:
Molarity = 0.0219 mol NaCl / 0.125 L = 0.175 M NaCl

To make a 0.175 M NaCl solution using 1.50 M NaCl, we can use the formula:
M1V1 = M2V2
where M1 is the initial molarity (1.50 M), V1 is the volume of the initial solution needed, M2 is the final molarity (0.175 M), and V2 is the final volume (125.0 mL or 0.125 L).

Solving for V1:
M1V1 = M2V2
(1.50 M)(V1) = (0.175 M)(0.125 L)
V1 = (0.175 M)(0.125 L) / 1.50 M
V1 = 0.0146 L or 14.6 mL

Therefore, your lab partner needs to use 14.6 mL of the 1.50 M NaCl solution to make a solution with the same concentration and volume as yours. The answer is B.

You Dissolve a 1