Question

Вычислите Какую массу металлического натрия нужно растворять в воде для того чтобы получить 10% раствор гидроксида натрия массовой 150г

Answer 1

2Na+2H2O=2NaOH+H2
m раствора(NaOH)=150 г
w=10%=0,1
m вещества(NaOH)=15 г
M(NaOH)=40 г/моль
U(NaOH)=0,375 моль
из уравнения следует,что U(Na)=U(NaOH)=0,375 моль
M(Na)=23 г/моль
m(Na)=8,625 г

Answer 2

Calculating the mass of metallic sodium needed

To calculate the mass of metallic sodium needed to make 150g of a 10% sodium hydroxide solution, we can follow these steps:

1. The mass percentage of sodium hydroxide (NaOH) in the solution is given as 10%. This means that for every 100g of the solution, there will be 10g of NaOH.

2. We want the final solution to have a mass of 150g. So the mass of NaOH needed will be 10% of 150g, which is 15g (0.1 * 150g).

3. The chemical reaction between sodium (Na) and water (H2O) to form sodium hydroxide (NaOH) and hydrogen (H2) gas is:

2Na + 2H2O → 2NaOH + H2

4. Using the molar masses:

- Mass of 1 mole Na = 23g - Mass of 1 mole NaOH = 40g - The balanced chemical equation shows that 1 mole of Na reacts with 1 mole of H2O to produce 1 mole of NaOH.

5. Using the mole ratio between sodium and sodium hydroxide from the balanced chemical reaction, we can determine that to get 15g of NaOH (0.375 moles NaOH), we need 0.375 moles of sodium.

6. Therefore, the mass of sodium needed is 0.375 moles * 23g/mole = 8.625g

So to make a 150g, 10% sodium hydroxide solution, the mass of metallic sodium needed is 8.625g.