Question

К смеи цинка и меди массой 40г прилили избыток соляной кислоты с массовой долей 20%. В результате реакции выделилось 8.96дм3 газа. Определите: а) массовую долю цинка и меди в смеси. б) массу раствора соляной кислоты, вступившей в реакцию. Очень надо(((

Answer 1

Подробное решение смотри на фото

Answer 2

Calculation of the Mass Fraction of Zinc and Copper in the Mixture

To determine the mass fraction of zinc and copper in the mixture, we need to use the given information about the reaction and the amount of gas produced.

Let's denote the mass of zinc as m_Zn and the mass of copper as m_Cu.

According to the given information, the total mass of the mixture is 40 g. Therefore, we can write the equation:

m_Zn + m_Cu = 40 g ---(Equation 1)

We also know that the reaction produced 8.96 dm³ of gas. Since the reaction involves the reaction of zinc and copper with excess hydrochloric acid, the gas produced is hydrogen gas (H₂). The volume of 1 mole of any gas at standard temperature and pressure (STP) is 22.4 dm³. Therefore, we can calculate the number of moles of hydrogen gas produced:

n(H₂) = V / V_m ---(Equation 2)

where V is the volume of gas produced (8.96 dm³) and V_m is the molar volume of gas at STP (22.4 dm³/mol).

Now, let's determine the number of moles of zinc and copper in the mixture. The balanced chemical equation for the reaction between zinc and hydrochloric acid is:

Zn + 2HCl → ZnCl₂ + H₂

From the equation, we can see that 1 mole of zinc reacts with 2 moles of hydrochloric acid to produce 1 mole of hydrogen gas. Therefore, the number of moles of zinc and copper can be calculated as follows:

n(Zn) = n(H₂) / 1 ---(Equation 3)

n(Cu) = n(H₂) / 1 ---(Equation 4)

Since the molar mass of zinc (Zn) is 65.38 g/mol and the molar mass of copper (Cu) is 63.55 g/mol, we can calculate the mass of zinc and copper in the mixture using the following equations:

m(Zn) = n(Zn) × M(Zn) ---(Equation 5)

m(Cu) = n(Cu) × M(Cu) ---(Equation 6)

where M(Zn) and M(Cu) are the molar masses of zinc and copper, respectively.

Finally, we can calculate the mass fraction of zinc and copper in the mixture using the following equations:

Mass fraction of zinc (w_Zn) = m(Zn) / (m(Zn) + m(Cu)) ---(Equation 7)

Mass fraction of copper (w_Cu) = m(Cu) / (m(Zn) + m(Cu)) ---(Equation 8)

Let's calculate the values using the given information.

Calculation:

Given: - Mass of the mixture (mixture of zinc and copper) = 40 g - Volume of gas produced (hydrogen gas) = 8.96 dm³ - Molar volume of gas at STP (V_m) = 22.4 dm³/mol - Molar mass of zinc (Zn) = 65.38 g/mol - Molar mass of copper (Cu) = 63.55 g/mol

Using Equation 2, we can calculate the number of moles of hydrogen gas produced:

n(H₂) = V / V_m = 8.96 dm³ / 22.4 dm³/mol = 0.4 mol

Using Equations 3 and 4, we can calculate the number of moles of zinc and copper:

n(Zn) = n(H₂) / 1 = 0.4 mol

n(Cu) = n(H₂) / 1 = 0.4 mol

Using Equations 5 and 6, we can calculate the mass of zinc and copper:

m(Zn) = n(Zn) × M(Zn) = 0.4 mol × 65.38 g/mol = 26.152 g

m(Cu) = n(Cu) × M(Cu) = 0.4 mol × 63.55 g/mol = 25.42 g

Using Equations 7 and 8, we can calculate the mass fraction of zinc and copper:

Mass fraction of zinc (w_Zn) = m(Zn) / (m(Zn) + m(Cu)) = 26.152 g / (26.152 g + 25.42 g) ≈ 0.506

Mass fraction of copper (w_Cu) = m(Cu) / (m(Zn) + m(Cu)) = 25.42 g / (26.152 g + 25.42 g) ≈ 0.494

Answer:

a) The mass fraction of zinc in the mixture is approximately 0.506 or 50.6%, and the mass fraction of copper is approximately 0.494 or 49.4%.

b) To calculate the mass of the hydrochloric acid solution that reacted, we need to determine the number of moles of hydrochloric acid that reacted. Since the reaction involved an excess of hydrochloric acid, we can assume that all of the hydrochloric acid reacted. The molar mass of hydrochloric acid (HCl) is 36.46 g/mol. Therefore, the mass of the hydrochloric acid solution that reacted can be calculated as follows:

Mass of hydrochloric acid solution = n(HCl) × M(HCl)

Since 1 mole of hydrochloric acid reacts with 1 mole of hydrogen gas, the number of moles of hydrochloric acid is equal to the number of moles of hydrogen gas produced:

n(HCl) = n(H₂) = 0.4 mol

Mass of hydrochloric acid solution = 0.4 mol × 36.46 g/mol ≈ 14.584 g

Therefore, the mass of the hydrochloric acid solution that reacted is approximately 14.584 g.