# Molarity

posted by
**Kellie**
.

A 15.7mL sample of HNO3 reacts to neutralize 27.7mL of 0.187M KOH solution. What is the molarity of the HNO3 solution?

HNO3 + KOH ==> KNO3 + HOH

mols KOH = L x M = 0.0277 x 0.187 = ??

mols HNO3 = mols KOH (1 mol reacts with 1 mol).

mols HNO3 = L x M

You have mols HNO3 and L, solve for M.

Check my thinking. Check my arithmetic.

I lost you on this one, I got a little confused on the 3rd step.

mols = L x M

mols KOH = 0.0277L x 0.187M = 0.00518 mols KOH.

The equation is

HNO3 + KOH ==> KNO3 + HOH

The equation shows 1 mol HNO3 reacts with 1 mol KOH; therefore, 0.00518 mols KOH requires 0.00518 mol HNO3.

Then mols HNO3 = L x M

0.00518 mol HNO3 = L x M

0.00518 mol HNO3 = 0.0157 L x M/

Solve for M.

Check to make sure I didn't make a typo.

Thanks for your help but I cant seem to get this one to come out to any of my possible answers. I think I am just getting confused on this one for some reason.

What are the possible answers?

0.165

0.330

0.498

0.298

0.198

0.0277*0.187/0.0157 = 0.32993 which rounds to 3 s.f. as 0.330. I see one like that. Don't you?

I got it finally.

Thank You

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