Question

При растворении сплава цинка с алюминием массой 3, 45 г. в сульфатной кислоте выделилось 1, 344 л водорода. Определите массовые доли цинкаи алюминия в сплаве

Answer 1

2Al + 3H2SO4 = Al2(SO4)3 + 3H2   (1)
Zn + H2SO4 = ZnSO4 + H2            (2)
n общая (H2) = V/Vm = 1,344 / 22,4 =0,06 моль
Пусть n1(H2) = x моль, тогда n2(H2) = 0,06 - x, тогда
n1(H2) : n(Al) = 3 : 2 
n(Al) = 2x/3  моль
n2(H2) = n(Zn) = 0,06 - x  моль
m(Al) = M*n = 27 *(2x/3) = 18x г
m(Zn) = M*n = 65 * (0,06 - x) = 3,9 - 65x
18x + 3,9 - 65x = 3,45
47x = 0,45
x = 0,00957 моль
m(Al) = 18 * 0,00957 = 0,17 г
m(Zn) = 3,9 - 65*0,00957 = 3,9 - 0,622 = 3,278 г 
(Массы металлов я находила из вот этих уравнений:
m(Al) = M*n = 27 *(2x/3) = 18x г
m(Zn) = M*n = 65 * (0,06 - x) = 3,9 - 65x
Они приведены выше)

w = m вещества / m раствора  *100%
w(Al) = 0,17 / 3,45   * 100% = 5 %
w(Zn) = 3,278 / 3,45   *100% = 95%
Ответ: 5% и 95%

Answer 2

Solving for the Mass Fractions of Zinc and Aluminum in the Alloy

To determine the mass fractions of zinc and aluminum in the alloy, we can use the information provided about the amount of hydrogen gas released when the alloy is dissolved in sulfuric acid.

Given: - Mass of the alloy (mixture of zinc and aluminum) = 3.45 g - Volume of hydrogen gas released = 1.344 L

First, we need to find the amount of hydrogen gas released at standard temperature and pressure (STP) using the ideal gas law. Then, we can use the stoichiometry of the reaction to find the mass fractions of zinc and aluminum in the alloy.

Calculating the Amount of Hydrogen Gas Released

Using the ideal gas law, we can calculate the amount of hydrogen gas released at STP:

The ideal gas law is given by: PV = nRT

Where: - P = pressure (atmospheres) - V = volume (liters) - n = amount of gas (in moles) - R = ideal gas constant (0.0821 L·atm/mol·K) - T = temperature (in Kelvin)

At STP, the pressure (P) is 1 atm and the temperature (T) is 273.15 K.

Using the given volume of hydrogen gas (1.344 L) and the ideal gas law, we can solve for the amount of hydrogen gas released (n).

Calculating the Mass Fractions of Zinc and Aluminum

The reaction of the alloy with sulfuric acid can be represented as follows: Zn + H2SO4 → ZnSO4 + H2 Al + H2SO4 → Al2(SO4)3 + H2

From the stoichiometry of the reaction, we can relate the amount of hydrogen gas released to the amount of zinc and aluminum in the alloy.

Let's calculate the mass fractions of zinc and aluminum in the alloy using the amount of hydrogen gas released and the stoichiometry of the reaction.

I will now perform the calculations and provide the results.