Question

В разбавленной серной кислоте растворили 13 грамм образца цинка содержащих 5% примесей.Какой объем водорода при н.у выделится,если выход продукта составляет 85% от теоретического возможного.Сколько граммов 20% кислоты потребуется для реакции?

Answer 1

Уравнение реакции:
Zn + H2SO4 = ZnSO4 + H2
Рассчитаем массу чистого цинка в пластине:
m(Zn) = 0.95*13г = 12,35г
n(Zn) = m/M = 12,35г/65г/моль = 0,19моль
По уравнению реакции:
n(H2) = n(Zn) = 0.19моль, с учетом выхода: 0,19моль*0,85 = 0,1615 моль
V(H2) = Vm*n = 0,1615моль*22,4л/моль = 3,6л
По уравнению реакции:
n(H2SO4) = n(Zn) = 0,19моль
m(H2SO4) = n*M = 0,19моль*98г/моль = 18,62г
m(раствора) = 18,62г/0,2 = 93,1г
Ответ: 3,6л, m = 93,1г

Answer 2

Calculation of the Volume of Hydrogen Gas Evolved

To calculate the volume of hydrogen gas evolved when 13 grams of a zinc sample containing 5% impurities is dissolved in diluted sulfuric acid, we need to consider 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. The molar mass of zinc is 65.38 g/mol, and the molar mass of sulfuric acid is 98.09 g/mol.

First, let's calculate the number of moles of zinc in the sample:

Number of moles of zinc = mass of zinc / molar mass of zinc

Number of moles of zinc = 13 g / 65.38 g/mol

Now, let's calculate the number of moles of hydrogen gas evolved:

Number of moles of hydrogen gas = Number of moles of zinc

Since the volume of 1 mole of any gas at standard temperature and pressure (STP) is 22.4 liters, we can calculate the volume of hydrogen gas evolved:

Volume of hydrogen gas = Number of moles of hydrogen gas * 22.4 liters/mol

However, we also need to consider the yield of the reaction, which is given as 85% of the theoretical yield. Therefore, the actual volume of hydrogen gas evolved will be:

Actual volume of hydrogen gas = Volume of hydrogen gas * Yield

Let's calculate the volume of hydrogen gas evolved:

Number of moles of zinc = 13 g / 65.38 g/mol = 0.1984 mol

Volume of hydrogen gas = 0.1984 mol * 22.4 liters/mol = 4.44 liters

Actual volume of hydrogen gas = 4.44 liters * 0.85 = 3.77 liters

Therefore, the volume of hydrogen gas evolved, at standard temperature and pressure (STP), is approximately 3.77 liters.

Calculation of the Amount of 20% Acid Required

To calculate the amount of 20% acid required for the reaction, we need to consider the stoichiometry of the reaction and the concentration of the acid.

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. Therefore, the molar ratio between zinc and sulfuric acid is 1:1.

Given that the zinc sample contains 13 grams and the impurities make up 5% of the sample, we can calculate the mass of pure zinc in the sample:

Mass of pure zinc = Mass of zinc sample - Mass of impurities

Mass of impurities = Mass of zinc sample * Percentage of impurities / 100

Mass of impurities = 13 g * 5 / 100 = 0.65 g

Mass of pure zinc = 13 g - 0.65 g = 12.35 g

Now, let's calculate the amount of 20% sulfuric acid required:

Amount of sulfuric acid = Mass of pure zinc / Molar mass of zinc

Amount of sulfuric acid = 12.35 g / 65.38 g/mol

Since the concentration of the sulfuric acid is given as 20%, we need to convert it to grams per liter (g/L) before calculating the volume:

Concentration of sulfuric acid = 20 g/100 mL = 200 g/L

Now, let's calculate the volume of 20% sulfuric acid required:

Volume of sulfuric acid = Amount of sulfuric acid / Concentration of sulfuric acid

Volume of sulfuric acid = (12.35 g / 65.38 g/mol) / (200 g/L)

Volume of sulfuric acid = 0.0946 L = 94.6 mL

Therefore, approximately 94.6 mL of 20% sulfuric acid is required for the reaction.