# Chemistry unit lab problem

#### phil22

Hi everyone,

Wondering if someone could help me with this lab problem. I can't get my head around it.
NaOH= 40,00g/mol
p = 2,10 g/cm3
I want 100 ml aq with 0,400 mol/kg

How do I solve this?

#### chemtopper

Hi everyone,

Wondering if someone could help me with this lab problem. I can't get my head around it.
NaOH= 40,00g/mol
p = 2,10 g/cm3
I want 100 ml aq with 0,400 mol/kg

How do I solve this?

First it is 40g/mol for NaOH which you can write as 0.04kg per mole
I want 100 ml aq with 0,400 mol/kg
what is it?
are you using commas in place of decimal?
please post question again accurately if you want help

#### phil22

Actually, I have found the answer to my problem, which was quite simple (given I'd not do it at 12:00).

The comas are from the French unit system in which we do not use dots to represents decimals.

Sorry for the confusion, I'll try to be clearer if I do post again!

Good evening

#### phil22

First it is 40g/mol for NaOH which you can write as 0.04kg per mole what is it?
are you using commas in place of decimal?
please post question again accurately if you want help
The 40.00g/mol represents the significative numbers

#### chemtopper

significant figures are not considered in molar masses or other conversion units .