# Homework Help: If V1 x M1 = V2 x M2, then why here 2V1 x M1 = V2 x M2?

1. Nov 19, 2017

### Indranil

1. The problem statement, all variables, and given/known data
In the first rection, NaOH + HCl = NaCl + H2O
From the first rection, we can write V1 x M1 = V2 x M2
In the second rection, 2NaOH + H2SO4 =Na2SO4 + H2O
From the second rection, Can we write V1 x M1 = V2 x M2?

2. Relevant equations
1. NaOH + HCl = NaCl + H2O
2. 2NaOH + H2SO4 =Na2SO4 + H2O

3. The attempt at a solution
From the second rection, I wrote the equation V1 x M1 = V2 x M2 but my book says I am wrong.

2. Nov 19, 2017

### epenguin

Your equation 2 is telling you the two molecules of NaOH react with one of H2SO4!

Do not rely too much on remembering blind formulae without understanding what they mean.

3. Nov 19, 2017

### Indranil

According to you what will be the solution for the second reaction?

4. Nov 19, 2017

### Staff: Mentor

Why don't you try to follow the stoichiometry and find out what the right approach is?

m1v1=m2v2 is one of the worst things taught in schools. Even if it is SOMETIMES true, people apply it blindly everywhere. Just forget you were ever taught it.

5. Nov 19, 2017

### epenguin

Sorry, it sounds as though you need to revise from your books quite elementary ideas of what molecules, moles, molarities and chemical formulae are and mean.
We help out here with misunderstandings of textbook material, but we do not write the textbooks, i.e. cannot do everything from zero, and we do not spoonfeed or give answers. (overlapped Borek's post.)