# chemistry moles question

A paper coffee cup is lined with a thin layer of plastic to make it waterproof. This plastic makes
up 5% of the mass of the cup and has the following molecular structure.
960 dm3
of a gaseous hydrocarbon monomer (measured at room temperature and pressure)
was used to make a certain number of plastic-lined cups.
It is proposed that a more environmentally-friendly, biodegradable plastic, poly(lactic acid),
could be used instead in the same proportions by mass (5%). Assume that any polymerisation
reaction has a 100% yield.
What mass of lactic acid (Mr = 90) is required to make the same number of biodegradable
cups?
(Ar values: H = 1; C = 12; O = 16. Assume that one mole of a gas occupies 24 dm3
at room
temperature and pressure.)

A 896 g
B 1120 g
C 1200 g
D 1400 g
E 1500 g
F 3000 g
G 3600 g

The answer is F but I keep geting G
difficult to answer without the molecular structure of the original plastic (i.e. what's the Mr?)
BUMP
Original post by hypez
A paper coffee cup is lined with a thin layer of plastic to make it waterproof. This plastic makes
up 5% of the mass of the cup and has the following molecular structure.
960 dm3
of a gaseous hydrocarbon monomer (measured at room temperature and pressure)
was used to make a certain number of plastic-lined cups.
It is proposed that a more environmentally-friendly, biodegradable plastic, poly(lactic acid),
could be used instead in the same proportions by mass (5%). Assume that any polymerisation
reaction has a 100% yield.
What mass of lactic acid (Mr = 90) is required to make the same number of biodegradable
cups?
(Ar values: H = 1; C = 12; O = 16. Assume that one mole of a gas occupies 24 dm3
at room
temperature and pressure.)

A 896 g
B 1120 g
C 1200 g
D 1400 g
E 1500 g
F 3000 g
G 3600 g

The answer is F but I keep geting G

Are you sure is it F ?
(edited 2 years ago)
Original post by hypez

Is this a BMAT question, if so what year?
Original post by chris01928
Is this a BMAT question, if so what year?

no its not bmat
Original post by eaglespirit
Are you sure is it F ?

The answer is D but I don't know how you get there. The moles of the gaseous hydrocarbon (is this the ethene monomer?) is 40mol which would give 40(28) = 1120g for the plastic assuming it's the ethene monomer, so surely this is the same as the mass needed of lactic acid?
BUMP