Question

calculate the mass and prepare 200ml 0.1M, 250 ml 0.2 N, 100 ml 3% of NaCl, Na2Co3 solution

Answer 1

You will have to find the molar mass here..

200 ml * 0.1 mol/ L * 1 L/ 1000 mL= 0.02M

250 ml* 0.2M/ L * 1L/ 1000 mL= 0.05M N

I somehow feel this problem is incomplete or either I am unable to understand the chemical compound name. Is there anymore to it?

Answer 2

You have six problems here. Three are for NaCl and three for Na2CO3.

For NaCl:
200 mL of 0.1M:
How many mols do you want? That's M x L = 0.1M x 0.200L = 0.02 mols.
How many grams is that.
mols = grams/molar mass. You know molar mass and mols; solve for grams.

250 mL of 0.2 N. How many equivalents do you want? That's N x L = 0.05 equiv.
How many grams is that?
#equivalents = grams/equilvalent weight. You know # equivalents and equivalent weight; solve or grams.

100 mL 3% NaCl (I assume that is % w/w.)
3g NaCl/100 g solution.

The Na2CO3 is done the same way.