# Homework Help: Stoichiometry again (using solutions)

1. Jul 12, 2009

### Attraction

1. The problem statement, all variables and given/known data

H2SO4 + Na2CO3 g Na2SO4 + H2O + CO2

Calculate the molarity of the H2SO4 solution if it takes 40.0 mL of H2SO4 to neutralize 46.7 mL of a 0.364 M Na2CO3 solution.

3. The attempt at a solution

The equation is balanced. My plan was

grams Na2CO3 --> mols Na2CO3--> molsH2SO4---> mols/litre H2SO4(equals Molarity).

my calculations...

.364gramsNa2CO3 x 1molNa2CO3/106gramsNa2CO3 x 1molH2SO4/1molNa2CO3 x 1000mlH2SO4/1LH2SO4

I know I am going wrong with the last bit but can't think of any other way to do it.

Help!?

2. Jul 12, 2009

### symbolipoint

At least you recognized the 1:1 mole ration between the acid and the carbonate.

moles Na2CO3=(0.467L)(0.364M)=moles of H2SO4.

Can you finish the rest? You used 40 mililiters of unknown concentration sulfuric acid.

3. Jul 12, 2009

### Attraction

I don't know how, but I copied the wrong question here in this thread. I started with grams but there is no grams in the question. The question I was supposed to copy was this one...

1. The problem statement, all variables and given/known data

Given the following equation:

H2SO4 + Na2CO3 ----> Na2SO4 + H2O + CO2

Calculate the molarity of the H2SO4 solution if it takes 40.0 mL of H2SO4 to neutralize 0.364 g of Na2CO3.

So my attempt at a solution is still the same. Sorry about that, I don't know how that happened but I should have rechecked before posting.

Anyway, with this new question, where we are given grams, is my method a bit closer to correct or not? I am having difficulty with the end, converting to moles/litre.

The equation is balanced. My plan was

grams Na2CO3 --> mols Na2CO3--> molsH2SO4---> mols/litre H2SO4(equals Molarity).

my calculations...

.364gramsNa2CO3 x 1molNa2CO3/106gramsNa2CO3 x 1molH2SO4/1molNa2CO3 x 1000mlH2SO4/1LH2SO4

I know I am going wrong with the last bit but can't think of any other way to do it.

Help!?

4. Jul 12, 2009

### Bohrok

Calculate the moles of H2SO4 that you have, right before the last part of your calculation. Since molarity = moles/liters, divide the moles of H2SO4 by 40.0mL in liters.

5. Jul 12, 2009

### Attraction

perfect, thanks man. I understand fully now.