Answer:
1. 77.5g,
2. 1.78 mol,
3. 281 g
4. add 80 mL of water
Explanation:
1. Molar mass (Na2O) = 2*23.0 + 16.0 = 62.0 g/mol
1.25 mol *62.0 g/1mol = 77.5 g Na2O
2. Molar mass (KOH) = 39.1 +16.0+1.0 = 56.1 g/mol
100 g * 1 mol/56.1 g = 1.78 mol KOH
3. Molar mass (KOH) = 39.1 +16.0+1.0 = 56.1 g/mol
5 mol * 56.1g/1 mol = 281 g KOH
4. M1V1 =M2V2
M - molarity, V- volume of solution
2.0M*20mL = 0.4M*V2
V2 = 2.0*20/0.4 = 100 mL
Volume of diluted solution = 100 mL
We have 20 mL of solution, we need 100 mL of solution,
so we need to add (100-20) =80mL of water.
Take 20 ml 2.0 Molar of solution of HCl , add 80 mL of water, then we get 100 mL 0.4 M solution of HCl.
