Question

9. A student collected the following data: Mass of gas = 0.800 g, temperature of the water bath = 95.0°C, barometric pressure = 760.0 torr, and the volume of the flask = 250.0 mL. Later the student was told that one drop (0.050g) of water had been present in the flask during the experiment and it completely vaporized, contaminating the gas. (a) Calculate the apparent molar mass, that is, the molar mass the student would get if he did not know that there were any impurities present. (b) Show how the student could still calculate the true molar mass of the gas. (c) Calculate the percentage of error in part (a).

          9. A student collected the following data: Mass of gas = 0.800 g, temperature of the water bath = 95.0°C, barometric pressure = 760.0 torr, and the volume of the flask = 250.0 mL. Later the student was told that one drop (0.050g) of water had been present in the flask during the experiment and it completely vaporized, contaminating the gas. (a) Calculate the apparent molar mass, that is, the molar mass the student would get if he did not know that there were any impurities present. (b) Show how the student could still calculate the true molar mass of the gas. (c) Calculate the percentage of error in part (a).

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9. A student collected the following data: Mass of gas = 0.800 g, temperature of the water bath = 95.0°C, barometric pressure = 760.0 torr, and the volume of the flask = 250.0 mL. Later the student was told that one drop (0.050g) of water had been present in the flask during the experiment and it completely vaporized, contaminating the gas. (a) Calculate the apparent molar mass, that is, the molar mass the student would get if he did not know that there were any impurities present. (b) Show how the student could still calculate the true molar mass of the gas. (c) Calculate the percentage of error in part (a).

Added by Chris W.

Chemistry: Structure and Properties

Nivaldo Tro 2nd Edition

Instant Answer

Solved by Expert Suman K

04/13/2022

Step 1

Given: Mass of gas (m) = 0.800 g Temperature (T) = 95.0°C = 368 K Pressure (P) = 760.0 torr = 1 atm Volume (V) = 250.0 mL = 0.250 L Using the ideal gas law: PV = nRT n = molar mass (M) / molar mass constant (R) m = n * M M = m / n Substitute the given values Show more…

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A student collected the following data: Mass of gas = 0.800 g, temperature of the water bath = 95.0°C, barometric pressure = 760.0 torr, and the volume of the flask = 250.0 mL. Later the student was told that one drop (0.050g) of water had been present in the flask during the experiment and it completely vaporized, contaminating the gas. (a) Calculate the apparent molar mass, that is, the molar mass the student would get if he did not know that there were any impurities present. (b) Show how the student could still calculate the true molar mass of the gas. (c) Calculate the percentage of error in part (a).

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Transcript

00:01 Hello guys, in this question, we have been given the value, the mass of gas that is equal to 0 .8 grams.

00:07 And the temperature given is 25 degrees celsius.

00:11 Pressure is 760 tour.

00:16 Volume is equal to 250 ml and.

00:23 And there is a presence of one drop of water that is equal to 0 .05 grams.

00:32 So this has been given and we have to calculate the molar mass the student would get if he did not know that there were any impurities present.

00:39 So if we assume there is no h2o at first, so our equation becomes pv is equal to n rt.

00:49 So we do not have moles but we can find moles by the formula that is, so n is equal to weight divided by molar mass and rt.

01:02 So from here we have all the values, that is p is equal to.

01:06 So if we have to find the mass, that is m, molar mass, so we can write it as 0 .8.

01:13 Plus r that is 0 .0821 multiplied by temperature that is 95 plus 273 degrees celsius 95 degrees celsius plus 273 so it will become kelvin and in the denominator we have 0 .25 multiplied by 1 so now from here we can say that the molar mass will be equal to 96.

01:57 So this is the answer for the first part of the question.

02:00 Now if the water is considered as impurity, then what will be the molar mass? so from here we have this formula that is pv is equal to moles of gas plus moles of water multiplied by rt...

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