C2 H2 Chemistry Block Test 1 2012_RevisionQuestions

HWA CHONG INSTITUTION C2 Block Test 1 H2 Chemistry 9746 Revision Questions

Prepared by Chee Yuan Jun 1

Name: ( ) CT Group: ________

C2 H2 Chemistry Block Test 1 2012

Overall Paper Format

Paper Type No. of questions No. of marks Duration

1 MCQ 20 20 30 min

2 Section

A:Structured

3 or 4

(includes

Planning)

40 60 min

Section B:

Free Response

1 20 30 min

Total 80

Paper 1 administered first followed by Paper 2 with a 15 min interval. 5 min break after Paper 2 Section A to hand in Section A and start

Section B. Topics Tested 1) Reaction Kinetics

2) Acid-Base Equilibrium

3) Introduction to Organic Cmpds

4) Alkanes

5) Alkenes

6) Arenes

7) Halogen Derivatives

8) Alcohols & Phenols

9) Carboxylic Acids & Derivatives

10) Aldehydes & Ketones ( MCQ only)

11) Planning

Marks:

Q1 /13 Q5 /20

Q2 /7 Q6 /20

Q3 /4 Extension 6b /3

Q4 /8 TOTAL /75

Note:

This paper does not test on alkanes and alkenes – you're expected to have already

studied them and be able to draw the mechanisms for any of the reactions.



1. [HCI 2009/2/2a,b,c] Glycolic acid CH2(OH)CO2H is an α-hydroxy acid (AHA)

used in various skin-care products.

a) 0.200 g of glycolic acid (Mr = 76.0) was dissolved in 20.0 cm3 water, and the

solution was titrated with 0.100 mol dm–3 aqueous NaOH. The following titration curve was obtained. (Ka of glycolic acid = 1.48 x 10–4 mol dm–3)

i) Calculate the volume of NaOH required to reach the equivalence point

in the titration.

ii) Calculate the pH of the solution at equivalence point.



iii) The table below shows the working range of some acid-base indicators.

Suggest an indicator which can be used in this titration and give a

reason for your choice.

[5]

b) Glycolic acid can undergo a series of reactions as shown below.

Step 1 Step 2

Multiple Steps Step 3

A

B

C



a) What reagents and conditions are required for the following steps?

i) Step 1:

ii) Step 2: ________________

iii) Step 3: ________________

b) Arrange the three compounds A, B, C in order of increasing ease of hydrolysis, giving your explanations clearly.

__________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________________. [6]

c) Compounds D and E below are also common α-hydroxy acids.

State the reagents and conditions you would use and the observations you would expect to make, in a simple chemical test, to distinguish glycolic acid from

i) Compound D:

ii) Compound E:

[2]



2a) Sulfuric acid, under different conditions, can behave as a dehydrating agent, a catalyst, an acid or an oxidizing agent. [7]

i) By means of equations, give one different reaction in each case where concentrated sulfuric acid behaves as a:

- Dehydrating agent

- Catalyst

ii) Using the reaction between concentrated sulfuric acid and sodium sodium bromide, write an equatino, including state symbols, to illustrate how concentrated sulfuric acid behaves as an:

- Acid

- Oxidizing Agent

b) Benzedrin is a stimulant and has the following structual formula:

Draw the structure of the organic products when benzedrin reacts with each of the following reagents:

a) Dilute nitric acid



b) Ethanoyl chloride

c) NaOH (aq), followed by CH3I and heat.

3) HCN gas is a highly poisonous gas that can cause permanent

damage to the central nervous system. The toxic level of HCN gas in the air is

about 0.001 mg dm-3.

a) Express the toxic level of HCN gas in the air in terms of mol dm-3. [1]

b) Describe the mechanism for the formation of cyanohydrins starting from propanal and HCN. [3]

4)

i) Account for the difference in the melting points of sodium chloride and silicon tetrachloride. [2]

ii) Explain briefly the difference in the pH values when MgCl2, AlCl3 and PCl5 are separately dissolved in water. Use equations to support your answer. [6]



5)

k



6) [N2011/3/5]

Extension 6b) Outline the mechanism for the conversion of phenol to 4-nitrophenol. [3]

C2 H2 Chemistry Block Test 1 2012_RevisionQuestions

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