Question

Определите массовую долю кислоты, образованной при растворении газа, выделенного в результате взаймодействия 19,4 Г сульфида цинка с 250мл 20% - ного раствора соляной кислоты (плотность = 1,1г/мл), в 200 мл воды.

Answer 1

ZnS+2HCl=ZnCl2+H2S Сперва вычислим , что берется в недостатке,а что в избытке n(ZnS)=m/M=19,4/97=0,2 моль n(HCl)=m/M=250*1,1*20%/36,5=1,51 моль Считаем по недостатку. m(H2S)=n*M=0,2*34=7,8 г w(H2S)=7,8/207,8=0,036(3,6%)

Answer 2

Calculation of the Mass Fraction of Acid Formed

To determine the mass fraction of acid formed when dissolving a gas, we need to consider the reaction between the gas and the acid. In this case, we have the reaction between 19.4 g of zinc sulfide (ZnS) and a 20% solution of hydrochloric acid (HCl).

The balanced chemical equation for the reaction between zinc sulfide and hydrochloric acid is as follows:

ZnS + 2HCl → ZnCl2 + H2S

From the equation, we can see that 1 mole of zinc sulfide reacts with 2 moles of hydrochloric acid to produce 1 mole of hydrogen sulfide gas.

To calculate the mass fraction of acid formed, we need to determine the moles of hydrogen sulfide gas produced and the moles of acid used.

1. Moles of Hydrogen Sulfide Gas Produced: - The molar mass of hydrogen sulfide (H2S) is approximately 34.08 g/mol. - We can calculate the moles of hydrogen sulfide gas produced using the given mass of zinc sulfide (19.4 g) and its molar mass. - Moles of H2S = Mass of ZnS / Molar mass of H2S - Moles of H2S = 19.4 g / 34.08 g/mol

2. Moles of Acid Used: - To determine the moles of acid used, we need to consider the concentration and volume of the hydrochloric acid solution. - The given solution is a 20% solution of hydrochloric acid, which means it contains 20 g of HCl per 100 mL of solution. - We can calculate the moles of acid used using the given volume of the hydrochloric acid solution (250 mL) and its concentration. - Moles of HCl = (Volume of HCl solution in liters) x (Concentration of HCl in mol/L) - Volume of HCl solution = 250 mL = 0.25 L - Concentration of HCl = 20 g/100 mL = 0.2 g/mL = 0.2 g/mL x (1 mL/1 cm^3) x (1 cm^3/1 mL) x (1 L/1000 cm^3) = 0.2 g/mL x 1 x 1/1000 = 0.2 g/L - Moles of HCl = 0.25 L x 0.2 g/L / Molar mass of HCl

3. Mass Fraction of Acid Formed: - The mass fraction of acid formed can be calculated by dividing the moles of acid used by the sum of the moles of acid used and the moles of hydrogen sulfide gas produced. - Mass Fraction of Acid Formed = Moles of HCl / (Moles of HCl + Moles of H2S)

Let's calculate the mass fraction of acid formed using the given values.

Calculation:

1. Moles of Hydrogen Sulfide Gas Produced: - Molar mass of H2S = 34.08 g/mol - Moles of H2S = 19.4 g / 34.08 g/mol = 0.569 mol 2. Moles of Acid Used: - Volume of HCl solution = 250 mL = 0.25 L - Concentration of HCl = 0.2 g/L - Molar mass of HCl = 36.46 g/mol - Moles of HCl = 0.25 L x 0.2 g/L / 36.46 g/mol = 0.137 mol 3. Mass Fraction of Acid Formed: - Mass Fraction of Acid Formed = Moles of HCl / (Moles of HCl + Moles of H2S) - Mass Fraction of Acid Formed = 0.137 mol / (0.137 mol + 0.569 mol) = 0.194 or 19.4%

Therefore, the mass fraction of acid formed in the reaction is approximately 19.4%.

Please note that the calculation assumes ideal conditions and does not take into account any side reactions or impurities in the reactants.

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