How many grams of Na2CO3 do you need to take to get 200 ml of 0.1 mol solution?

Given:
V solution (Na2CO3) = 200 ml = 0.2 l
Cm (Na2CO3) = 0.1 mol / L

Find:
m (Na2CO3) -?

Solution:
1) Calculate the amount of Na2CO3 substance:
n (Na2CO3) = Cm (Na2CO3) * V solution (Na2CO3) = 0.1 * 0.2 = 0.02 mol;
2) Calculate the molar mass of Na2CO3:
M (Na2CO3) = Mr (Na2CO3) = Ar (Na) * N (Na) + Ar (C) * N (C) + Ar (O) * N (O) = 23 * 2 + 12 * 1 + 16 * 3 = 106 g / mol;
3) Calculate the mass of Na2CO3:
m (Na2CO3) = n (Na2CO3) * M (Na2CO3) = 0.02 * 106 = 2.12 g.

Answer: The mass of Na2CO3 is 2.12 g.