DF aprst: Polymers; ideal gas equation; isomerism Flashcards
What is a co-polymer?
A polymer derived from 2+ species of monomer.
Describe the structure of an A-B polymer.
Arrangement regular + alternating.
What is a benzene group otherwise known as?
A phenyl group.
Suggest the mechanism by which addition polymerisation occurs.
Electrophilic addition
Double bond attacks an electrophile, forming a carbocation which further double bonds attack in a domino-like manner
But-1-ene + propene
Draw the repeating unit of the A-B copolymer formed when chloroethene and ethenyl ethanoate undergo addition polymerisation.
Ethenyl ethanoate = CH3COOCH=CH2
Why does one mole of a gas always occupy 24 dm3 at RTP, regardless of the size of gas molecules?
Variations in molecular size are negligable compared to the distance between molecules.
What is standard temperature?
273 K
0oC
What volume of air is needed to completely burn 15 cm3 of hexane vapour? Assume that all volumes are measured at RTP and that air contains 21% oxygen.
C6H14 + 9.5O2 → 6CO2 + 7H2O
Equal moles of any two gases occupy the same volume at RTP
Vol O2 = 15 x 9.5 = 142.5 cm3
Vol air = 142.5 x 100/21 = 680 cm3
- State the ideal gas equation.
- State the units used for each quantity, excluding the constant.
PV = nRT
- P in Pa (Nm-1)
- V in m3
- n in mol
- T in K
What is the volume of 1 mole of a gas, in dm3, at 100 kPa and 16oC?
PV = nRT so V = nRT/P
P = 100 kPa = 100 x 103 Pa
T = 16oC = 289 K
V = 1 x 8.314 x 289 / (100 x 103) = 0.024 m3 = 24 dm3
The following shows the complete combustion of octane:
C8H18(g) + 12.5O2(g) → 8CO2(g) + 9H2O(g)
3.42 g of octane is burned per second in an engine. The exhaust gases are produced at 550oC and 1.50 x 105 Pa.
Calculate the volume of exhaust gases, in dm3, produced per second. Assume that carbon dioxide and water vapour are the only gases present in the exhaust.
Rearrange equation
pV = nRT → V = nRT/P
Find n, combined mol of CO2 + H2O
n octane = 3.42/114 = 0.03
Therefore n (CO2 + H2O) = 0.03 x (8 + 9) = 0.51 mol
Convert temperature
550oC + 273 = 823 K
Find volume in m3 and convert to dm3
V = (0.51 x 8.314 x 823) / (1.5 x 105) = 0.0233 m3
x 103 = 23.3 dm3
Hydrogen can be stored in car tanks at a pressure of 7.0 × 104 kPa.
The volume of a tank is 70 dm3 and the temperature 20°C. Calculate the maximum energy that could be produced by burning all the hydrogen in the tank.
∆cH for H2 = –242 kJ mol-1
Give your answer in standard form, to two significant figures.
pV = nRT → n = PV/RT
P = 7 x 104 kPa = 7 x 107 Pa
V = 70 dm3 = 70 x 10-3 m3
T = 20oC = 293 K
Mol H2 = n = (7 x 107 x 70 x 10-3) / (8.314 x 293) = 2011 mol
E = 2011 x 242 = 490,000 kJ = 4.9 x 105 kJ
What are structual isomers?
- Same molecular formulae
- Different structural formulae (ordering of atoms)
Name and describe the 3 types of structural isomerism.
Chain: different branching of chains; 4+ carbons needed
Position: different locations of a functional group
Functional group: different functional groups / homologous series