Question

What is the molarity of a 250ml KCl solution made by diluting 175mL of a 3.00 M solution?

Answer 1

Answer:

2.1 M

Explanation:

The dilution equation is $M_{s} V_{s} = M_{d} V_{d}$.

$M_{s}$ = the molarity of the sock solution

$V_{s}$ = the volume of the sock solution

$M_{d}$ = the molarity of the diluted solution

$V_{d}$ = the volume of the diluted solution

The stock solution would be what is doing the diluting, so "175 mL of a 3.00 M solution". So $M_{s}$ = 3.00 M. Then: Converting 175 mL to liters: $175 mL * \frac{1 L}{1000mL} = 0.175 L$ (This is $V_{s}$)

And converting 250 mL KCl to liters: $250 mL * \frac{1 L}{1000mL} = 0.250 L$ (This will be $V_{d}$)

Then, we plug in our given into the dilution equation, resulting in:

$3.00 M * 0.175 L = M_{d} * 0.250 L$ (divide both sides by 0.250 L, in order to get $M_{d}$ by itself)

$\frac{3.00 M * 0.175 L}{0.250 L} = M_{d}$

$M_{d} = 2.1 M$

So, the molarity of 250 mL KCl made by diluting 175 mL of a 3.0 M solution would be 2.1 M (mol/L).

Hopefully this helped you understand the topic a little bit better. I just finished molarity and dilutions in Chemistry last week. Good luck!