please help with questions 2 and 4... the lab is Determining the Molar Mass of a

Question

please help with questions 2 and 4... the lab is Determining the Molar Mass of a Volatile Liquid

'Questa ianym 217 corrects for these Waals equation, a modification of the Ideal Gas Law der deviations from ideality The R V. n, R, and T terms are the same as defined previously The R Vn corrects for attractive forces between molecules while the b term the actual volume occupied by the gas molecules themselves. including Van der Waals constants, for several volatile or included in Table 1. corrects for phc ganic liquids are Table 1. Physical Data for Volatile Organic Liquids Formula | Molar Mass | a (Latm/moP) | b (L/mol) |b.?. (C) Compound Methanol Ethanol CH OH CH,CH2OH 32.04 9.52 12.02 0.0670 65.0 0.084178.5 0.1019 82.4 0.0994 565 0.1460 36.0 0.1735 69.0 0.1424 80.7 0.0305100.0 46.07 Propanol CH,CH2CH2OH 60.09 14.92 Acetone Pentane Hexane Cyclohexane C-&H12; CH COCH CH,(CH),CH, 172.14 CH3(CH2)4CH3 86.17 58.02 13.91 19.01 24.39 84.15 Water H2O 18.02 5.46

Explanation / Answer

Q2.

When the foil cap is torn, the vapor of volatile liquid escapes. That says that the weight or mass of volatile vapor decreases and is less than the actual weight or mass.

This effects the mass of vapor but 'Molar mass' remains constant.

we know that no of moles, n = weight / molar mass. So, as the molar mass is constant, the no of moles compensate the mass of vapor by decreasing.

Q4.

Constant "a" represents the magnitude of attractive forces between the molecules of gas.  

Higher the given value of "a" higher will be the attractive forces. So, from the table given Hexane has highest value of "a" which says that hexane has highest magnitude of attraction forces (we can also see that it has more no of similar type of bonds in form of 'H-bonding') and water has least value of "a" which says that water has lowest magnitude of attractive forces (only 2H-bonds).

We can also explain and understand in other way too. That is Higher the same type of bonding present (attractive forces), Higher will be the value of "a"

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