Question

3,73 г смеси цинка и цинк оксида обработали избытком раствора разбавленной сульфатной кислоты. При этом выделилось 0,48 л газа (н.у). Определить массовую долю цинка в смеси.

Answer 1

Zn + H2SO4 = ZnSO4 + H2

ZnO + H2SO4 = ZnSZO4 + H2O
Рассчитаем количество вещества водорода:

n = V/Vm = 0.48/22.4 = 0,021моль

Поуравнению реакции:

n(Zn) = n(H2) =  0,021моль

Рассчитаем массу цинка:

m = n*M = 1,365г

Рассчитаем массовую долю:

w = m(Zn)/m(см)*100% = 1,365г/3,73г*100% = 36,5%

Answer 2

Calculation of Zinc Mass Fraction in the Mixture

To determine the mass fraction of zinc in the mixture, we need to use the information provided about the reaction between the zinc and zinc oxide mixture and the excess sulfuric acid solution.

The given information states that 3.73 g of the mixture of zinc and zinc oxide reacted with an excess of diluted sulfuric acid, resulting in the evolution of 0.48 L of gas at standard temperature and pressure (n.у).

To calculate the mass fraction of zinc, we can use the stoichiometry of the reaction and the ideal gas law.

The balanced chemical equation for the reaction between zinc and sulfuric acid is:

Zn + H2SO4 → ZnSO4 + H2

From the equation, we can see that 1 mole of zinc reacts with 1 mole of sulfuric acid to produce 1 mole of hydrogen gas.

To calculate the number of moles of hydrogen gas produced, we can use the ideal gas law:

PV = nRT

Where: - P is the pressure (standard pressure at 1 atm) - V is the volume of gas (0.48 L) - n is the number of moles of gas (to be determined) - R is the ideal gas constant (0.0821 L·atm/mol·K) - T is the temperature in Kelvin (standard temperature at 273 K)

Rearranging the equation to solve for n, we have:

n = PV / RT

Substituting the given values, we get:

n = (1 atm) * (0.48 L) / (0.0821 L·atm/mol·K * 273 K) = 0.022 mol

Since 1 mole of zinc reacts with 1 mole of sulfuric acid to produce 1 mole of hydrogen gas, the number of moles of zinc in the reaction is also 0.022 mol.

Now, we can calculate the mass of zinc in the mixture using the molar mass of zinc (65.38 g/mol):

Mass of zinc = number of moles of zinc * molar mass of zinc = 0.022 mol * 65.38 g/mol = 1.44 g

Finally, we can calculate the mass fraction of zinc in the mixture:

Mass fraction of zinc = (mass of zinc / mass of mixture) * 100% = (1.44 g / 3.73 g) * 100% ≈ 38.6%

Therefore, the mass fraction of zinc in the mixture is approximately 38.6%.