Question

Сколько граммов смеси калия и натрия следует растворить в воде для выделения газа (л, н. у) объемом 11.2 л, если в составе смеси массовая доля натрия =23 %

Answer 1

Дано:
V(H2)=11,2 л
ω(Na)= 23%  или 0,23
Найти:
m(Na)-?
m(K)-?
Решение.
Примем массу смеси за х г, тогда 
m(Na) = 0.23х
m(K) = 0,77х
n(Na) = m/M = 0,23х г/23 г/моль = 0,01х моль
n(K) = m/M = 0,77х г/39 г/моль = 0,0195х моль
2Na + 2H2O = 2NaOH + H2
2K + 2H2O = 2KOH + H2
Из уравнений химических реакций следует, что
n(K)+n(Na)=2n(H2)
n(K)+n(Na) = 2*0.5 моль = 1 моль
0,0195х+0,01х = 1
х= 33,9 
m(Na)= 33.9 г * 0,23 = 7,8 г
m(K) = 33,9 г*0,77 = 26,1 г
Ответ: 7,8 г; 26,1 г

Answer 2

Calculating the Mixture of Potassium and Sodium for Gas Evolution

To calculate the amount of the potassium and sodium mixture needed to produce a gas volume of 11.2 L, given that the mass fraction of sodium is 23%, we can use the following steps:

1. Determine the Molar Mass of the Mixture: - The molar mass of the mixture can be calculated using the mass fractions of potassium and sodium.

2. Calculate the Moles of the Mixture: - Using the molar mass, we can calculate the moles of the mixture present in the given mass.

3. Use Stoichiometry to Find the Gas Volume: - Once we have the moles of the mixture, we can use stoichiometry to find the gas volume produced.

Calculation Steps

1. Determine the Molar Mass of the Mixture: - The molar mass of the mixture can be calculated using the mass fractions of potassium and sodium. - The molar mass of potassium (K) is approximately 39.10 g/mol, and the molar mass of sodium (Na) is approximately 22.99 g/mol.

2. Calculate the Moles of the Mixture: - Given that the mass fraction of sodium is 23%, the mass fraction of potassium would be 100% - 23% = 77%. - Let's assume we have 100 grams of the mixture. Then, the mass of sodium would be 23 grams and the mass of potassium would be 77 grams. - Now, we can calculate the moles of sodium and potassium using their respective molar masses.

3. Use Stoichiometry to Find the Gas Volume: - Once we have the moles of the mixture, we can use stoichiometry to find the gas volume produced. - The balanced chemical equation for the reaction that produces the gas would be needed to proceed with this step.

Conclusion

By following these steps, we can calculate the amount of the potassium and sodium mixture needed to produce a gas volume of 11.2 L, given the mass fraction of sodium is 23%. If you have the balanced chemical equation for the reaction, we can proceed with the stoichiometry calculation to find the exact amount of the mixture needed.