consider each error below. Explain how it would affect the calculated Molar Mass

Question

consider each error below. Explain how it would affect the calculated Molar Mass of the volatie tqidChoose the option that best explains each situation Molar Mass of volatile liquid calculated Water droplets from the water bath remained on the flask during weighing (after heating) OUnaffected. This is not included in the calculation for molar mas OToo low. This would make the molar mass of volatile liquid be calculated as too low OToo high. The additional mass would cause the calculated number of mol to increase OToo high. Temperature and molar mass are inversely related. As T decreases, n will decrease, causing MM to The thermometer is not calibrated and gives a reading that is 2 degrees below the actual temperature of the water bath. increase OToo low. Temperature and molar mass are inversely related. As T increases, n will increase, causing MM to decrease OToo low. Temperature and molar mass are directly related As T decreases n will increase, causing MM to decrease. OToo high, Temperature and molar mass are directly related. As T increases, n will decrease, causing MM to increase OUnaffected. The temperature will not affect calculated molar mass. OToo high. Pressure and molar mass are directly related. As P decreases, n will increase, causing the molar mass to be The barometer gives a pressure of the lab that is actually 0.015 atm higher than ik actually is. calculated as too high OUnaffected. The pressure will not change the molar mass calculated OToo low. Pressure and molar mass are directly related. As P decreases, n will increase, causing molar mass to be calculated as too low OToo low. Pressure and molar mass are inversely relaced. As P increases, n will also increase, causing the molar mass to be calculated as too low OToo high. Pressure and molar mass are inversely related. As P increases, n will decrease, causing the molar mass to be calculated as too high. OToo high. Volume and molar mass are inversely related.As V decreases, n will be calculated as too low, causing. molar mass to be calculated as too high When measuring the flask, some water spilled. This caused the volume of the flask to be recorded as 8.5 ml too low OToo low. Volume and molar mass are inversely related. As V increases, n will be calculated as too high, causing molar OToo low. Volume and molar mass are directly related As V decreases, n will also increase, causing the molar mas mass to be calculated as too low calculated to also decrease. OToo high. Volume and molar mass are directly related. As Vincreases, n will also decrease, causing the calculated molar mass to also increase. OUnaffected. This error will not change the calculated molar mass. While heating an air bubble below the flask made it look like there was volatile liquid in the flask, You heated the flask 7 minutes longer than you should have. OUnaffected. The molar mass is not directly related to the length of time the flask is heated OToo low. This will cause most of the volatile liquid to o escape and result in the molar mass being calculated as too low OToo high Heating the fask for too long will cause the molar mass to be calculated as too high. Points possible: 3 Unlimited atzempts

Explanation / Answer

Molar mass determination of volatile liquid:

To determine the molar mass (M)of a volatile liquid,the liquid is evaporated in a flask of measured volume(V) being submerged in boiling water,so that the temperature(T) of water equals that of gas in the flask.After the liquid condenses,the mass of the flask+liquid is measured and substracted from the mass of flask to calculate the mass of liquid(m).Barometric pressure (P)is also noted and all the values plugged in the ideal gas equation,PV=nRT=m/M RT

or,PV=(RTm/M)

Answers)

1) mass of the condensed vapour=(mass of weighing flask+mass of mass of the condensed vapour+mass of water droplets)-(mass of weighing flask)=mass of mass of the condensed vapour+mass of water droplets

So,mass of vapour (m) will be higher ,which gives high value for molar mass (M),

M=(RTm/PV)

--too high

2) Temperature noted for water bath (T) is actually estimated to be the temperature of vapours,So lower T will give low M

M=(RTm/PV)

--Too low ,T is directly related to M,n=mol of vapours,as T decreases, n=m/M inceases ,m increases

3)If barometric P is high then,M is low as they are inversely related

4) If Volume is (V) is low, then M is high as they are directly related

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