A mixture of hydrogen sulfide and hydrogen iodide with a volume of 1.792 L

| January 31, 2021 | education

A mixture of hydrogen sulfide and hydrogen iodide with a volume of 1.792 L was passed through an excess of silver nitrate solution. This formed a precipitate weighing 19.19 g. Determine the mass and volume fractions of gases in the original mixture.

Let’s write down given:

V (HI + H2S) = 1,792l

+ AgNO3

m (sediment) = 19.19 g

ϕ (HI) -?

ϕ (H2S) -?

Decision.

1) Let us write the reaction equation for the interaction of HI and H2S with AgNO3:

HI + AgNO3 = AgI + HNO3

H2S + 2 AgNO3 = Ag2S + 2НNO3

2) Let the volume of HI, which entered into the reaction, is equal to x l, then the volume of H2S will be equal to (1.792 – x) l;

Let the mass of AgI, formed as a result of the reaction, be equal to y g, then the mass of Ag2S is equal to (19.19 – y) g.

Let’s find the molar masses of substances:

M (AgI) = 108 + 127 = 235 g / mol

M (Ag2S) = 108 * 2 + 32 = 248 g / mol

V m = 22.4 l / mol

Let’s make the proportions:

(1) x / 22.4 = y / 235

(2) (1.792 – x) / 22.4 = (19.19 – y) / 248

(1.792 – x) * 248 = (19.19 – y) * 22.4

444.416 – 248 x = 429, 856 – 22.4 y

From the first proportion, we express y;

Y = 235 x / 22.4; y = 10.49 x;

Substitute the value of y into the second proportion:

444.416 – 248 x = 429, 856 – 10.49 x * 22.4

444.416 – 248 x = 429, 856 – 234.976 x

– 248 x +234.976 x = 429.856 – 444.416

– 13.024 x = – 14.56

X = 14.56 / 13.024

X = 1.118 l (HI)

V (H2S) = 1.792 L – 1.18 L = 0.674 L

3) Calculate the volume fraction of gases in the mixture:

ϕ (HI) = 1.118 * 100% / 1.792

ϕ (HI) = 62.38%

ϕ (H2S) = 0.674 l * 100% / 1.792

ϕ (H2S) = 37.62%

4) Let’s calculate the masses of each gas in the mixture:

M (HI) = 128 g / mol; m = V * M / Vm

m (HI) = 1.118 L * 128 g / mol / 22.4 L / mol = 6.389 g

M (H2S) = 34 g / mol

m (H2S) = 0.674 l * 34 g / mol / 22.4 l / mol = 1.023 g

m (mixture) = 6.389 g + 1.023 g = 7.412 g

4) Calculate the mass fraction of each gas in the mixture:

W (HI) = 6.389 g * 100% / 7.412 g = 86.2%

W (H2S) = 100% – 86.2% = 13.8%

Answer: ϕ (HI) = 62.38%, ϕ (H2S) = 37.62%, W (HI) = 86.2%, W (H2S) = 13.8%



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