AS-Level Chemistry: June 2017 Paper 2 PP Flashcards

1
Q

This Gas Decomposes on Heating.
Explain why an Increase in Temperature Increases the Rate at which this Gas Decomposes.

(2 marks)

A

-An Increases in the Number of Molecules with Energy >_Activation Energy.

-More Successful Collisions. Rate of Reaction Increases.

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2
Q

Compounds A, B and C all have the Molecular Formula C5H10
A and B Decolourise Bromine Water but C does not. B exists as two Stereoisomers but A does not show Stereoisomerism.
Use this information to deduce a possible Structure for each of Compounds A, B and C and explain your deductions.
State the meaning of the term ‘Stereoisomers’ and explain how they arise in compound B.

(6 marks)

A

-A & B are Unsaturated. Do not Contain C=C Double Bond

-Because they Decolourise Bromine Water.

-Suitable Structures of A: Pent-1-ene, 2-methylbut-1-ene, 3-methylbut-1-ene, 2-methylbut-2-ene.

-B: Pent-2-ene

-Suitable Structure of C: Cyclopentane, etc.

-Stereoisomerism: Molecules with the Same Structural Formula but a Different Arrangement of Atoms.
C=C cannot rotate.

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3
Q

Write an Equation for the Complete Combustion of Propane in Oxygen.

(1 mark)

A

C3H8 + 5O2 —–> 3CO2 + 4H2O

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4
Q

The student used a wash bottle containing Deionised Water when approaching the end-point to rinse the Inside of the Conical Flask.
Explain why this improved the Accuracy of the Titration.

(1 mark)

A

Ensures no Acid/Alkali is left on the side of the Flask.

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5
Q

Give the meaning of the term Concordant Titres.

(1 mark)

A

Titres that are within 0.05cm^3 of each other.

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6
Q

Carbocation D can undergo a type of Reaction called a Rearrangement to form Carbocation E. In this Reaction, a Hydrogen Atom and its Bonding Pair of Electrons move from Carbon A to Carbon B.
Use your knowledge of Carbocations to explain why this Rearrangement takes place.

(2 marks)

A

-More Stable Carbocation Formed.

-Changes from Secondary to Tertiary Carbocation.

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7
Q

Cyclohexene is prepared by the dehydration of Cyclohexanol using Concentrated Phosphoric Acid as a Catalyst. The Structure of Concentrated Phosphoric Acid is shows.

OH
 | O=P-OH
 |
OH

Identify the factors that influence the Boiling Points of each of the Compounds in this Reaction Mixture. State how and explain why Cyclohexene can be Separated from the Reaction Mixture.

(6 marks)

A

-Cyclohexene: Weak Van der Waals’ Forces between Molecules.

-Cyclohexanol: Hydrogen Bonds between Molecules.

-Phosphoric Acid: Hydrogen Bonds between Molecules.

-Cyclohexene has the Weakest Intermolecular Forces.

-Separated by Distillation.

-Cyclohexene has the Lowest BP. Boils off first.

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8
Q

Chloroethene has a Melting Point of -154ºC
All types of PVC Melt at Temperatures over 100ºC
Explain why PVC Melts at a Higher Temperature than Chloroethene.

(2 marks)

A

-PVC is a much Bigger/Longer Molecules. Has More Electrons & Bigger Surface Area.

-PVC has Stronger Van der Waals’ / Dipole-Dipole Intermolecular Forces.

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9
Q

Use your understanding of the Properties of PVC to explain whether you would expect to find a Plasticiser in the PVC used to Insulate Electrical Cables.

(1 mark)

A

Need both ideas that:

-It is present AND
-Because PVC needs to be flexible/bendy

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10
Q

Which is the most likely Bond Angle around the Oxygen Atom is Ethanol? (1)

A) 104.5º
B) 109.5º
C) 120º
D) 180º

A

A) 104.5º

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11
Q

Which Compound is a Structural Isomer of Z-but-2-ene? (1)

A) Butane
B) E-but-2-ene
C) Cyclobutane
D) Methylbut-2-ene

A

C) Cyclobutane

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12
Q

Which Equation is a propagation step in the Conversion of Trichloromethane into Tetracloromethane by Reaction with Chlorine in the Presence of Ultraviolet Light? (1)

A) CHCl3 + Cl2 ⟶ CCl4 + HCl

B) *CCl3 + *Cl ⟶ CCl4

C) CHCl3 + *Cl ⟶ CCl4 + *H

D) *CCl3 + Cl2 ⟶ CCl4 + *Cl

A

D

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13
Q

Which Compound has the Fastest Rate of Reaction with Potassium Cyanide to form Pentanenitrile? (1)

A) 1-bromobutane
B) 1-chlorobutane
C) 1-fluorobutane
D) 1-iodobutane

A

D

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14
Q

Which Alcohol can be Oxidised by Acidified Potassium Dichromate(VI) but cannot be Dehydrated by Heating with Concentrated Sulfuric Acid? (1)

A) 2.3-dimethylbutan-2-ol

B) 2,2-dimethylpropan-1-ol

C) 2-methylpropan-2-ol

D) pentan-3-ol

A

B

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15
Q

How many Structural Isomers are there with the Molecular Formula C3H6BrCl? (1)

A) 4
B) 5
C) 6
D) 7

A

B) 5

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16
Q

Which sample contains the most Molecules? (1)

A) 2.10*10^22 molecules of methane, CH4

B) 1.00g of Oxygen, O2

C) 65.0mg of Hydrogen, H2

D) 0.0300mol of ethane, C2H6

17
Q

Which Compound forms a Molecular Ion with a different precise Molecular Mass from the other three? (1)

A) Butanone
B) Cyclobutanol
C) Dimethylpropane
D) Methylpropanal