SOUTH AUSTRALIAN MATRICULATION

2012 APRIL INTAKE ASSESSMENT 3

ORGANIC AND BIOLOGICAL CHEMISTRY AND CHROMATOGRAPHY

Time: 90 minutes

Approved dictionaries and calculators may be used.

Instructions to Candidates

1. Answer ALL questions. 2. There is no need to fill all of the space provided; clear, well-expressed answers are

required. If you delete part or all of an answer you should clearly indicate your final answer.

3. The total mark is 70.

CHEMISTRY

20 pages 5 questions

Name : _____________________________________

Student No. : _____________________________________

Group : _____________________________________

Question Marks

1 /16m

2 /16m

3 /13m

4 /13m

5 /12m

TOTAL /70m

Purpose:

This task allows you to demonstrate your knowledge and understanding of the concepts of organic and biological chemistry.

Description of the assessment:

This test assesses:

1) knowledge and understanding of the concepts of organic chemistry 2) use of systematic nomenclature 3) interpretation and use of structural formulae 4) knowledge and understanding of the nature and reactions of the functional group studied 5) application of concepts to solve problems in familiar and unfamiliar contexts 6) knowledge and understanding of practical procedures - chemical synthesis & organic testing 7)

Assessment conditions:

1) Time allowance: 90 minutes 2) You may consult the periodic table.

Assessment Design Criteria Grade

Analysis & Evaluation

(AE)

AE1 Analysis of data and concepts and their connections, to formulate conclusions and make relevant predictions.

AE2 Evaluation of procedures, with suggestions for improvement.

Application (A)

A1 Application of chemistry concepts and evidence from investigations to solve problems in new and familiar context.

A2 Use of appropriate chemistry terms, conventions, formulae and equations.

A3 Demonstration of skills in individual and collaborative work.

Knowledge & Understanding

(KU)

KU1 Demonstration of knowledge and understanding of chemistry concepts.

KU2 Use of knowledge of chemistry to understand and explain social or environmental issues.

KU3 Communication of knowledge of chemistry in different formats

OVERALL GRADE

Performance Standards for Stage 2 Chemistry – Assessment 3

Investigation Analysis and Evaluation Application Knowledge and Understanding

A Designs logical, coherent, and detailed chemistry investigations.

Critically and logically selects and consistently and appropriately acknowledges information about chemistry and issues in chemistry from a range of sources.

Manipulates apparatus and technological tools carefully and highly effectively to implement well-organised safe and ethical investigation procedures.

Obtains, records, and displays findings of investigations using appropriate conventions and formats accurately and highly effectively.

Critically and systematically analyses data and their connections with concepts, to formulate logical and perceptive conclusions and make relevant predictions.

Critically and logically evaluates procedures and suggests a range of appropriate improvements.

Applies chemistry concepts and evidence from investigations to suggest solutions to complex problems in new and familiar contexts.

Uses appropriate chemical terms, conventions, formulae, and equations highly effectively.

Demonstrates initiative in applying constructive and focused individual and collaborative work skills.

Consistently demonstrates a deep and broad knowledge and understanding of a range of chemistry concepts.

Uses knowledge of chemistry perceptively and logically to understand and explain social or environmental issues.

Uses a variety of formats to communicate knowledge and understanding of chemistry coherently and highly effectively.

B Designs well-considered and clear chemistry investigations.

Logically selects and appropriately acknowledges information about chemistry and issues in chemistry from different sources.

Manipulates apparatus and technological tools carefully and mostly effectively to implement organised safe and ethical investigation procedures.

Obtains, records, and displays findings of investigations using appropriate conventions and formats mostly accurately and effectively.

Clearly and logically analyses data and their connections with concepts, to formulate consistent conclusions and make mostly relevant predictions.

Logically evaluates procedures and suggests some appropriate improvements.

Applies chemistry concepts and evidence from investigations to suggest solutions to problems in new and familiar contexts.

Uses appropriate chemical terms, conventions, formulae, and equations effectively.

Applies mostly constructive and focused individual and collaborative work skills.

Demonstrates some depth and breadth of knowledge and understanding of a range of chemistry concepts.

Uses knowledge of chemistry logically to understand and explain social or environmental issues.

Uses a variety of formats to communicate knowledge and understanding of chemistry coherently and effectively.

C Designs considered and generally clear chemistry investigations.

Selects with some focus, and mostly appropriately acknowledges, information about chemistry and issues in chemistry from different sources.

Manipulates apparatus and technological tools generally carefully and effectively to implement safe and ethical investigation procedures.

Obtains, records, and displays findings of investigations using generally appropriate conventions and formats with some errors but generally accurately and effectively.

Analyses data and their connections with concepts, to formulate generally appropriate conclusions and make simple predictions, with some relevance.

Evaluates some procedures in chemistry and suggests some improvements that are generally appropriate.

Applies chemistry concepts and evidence from investigations to suggest some solutions to basic problems in new or familiar contexts.

Uses generally appropriate chemical terms, conventions, formulae, and equations with some general effectiveness.

Applies generally constructive individual and collaborative work skills.

Demonstrates knowledge and understanding of a general range of chemistry concepts.

Uses knowledge of chemistry with some logic to understand and explain one or more social or environmental issues.

Uses different formats to communicate knowledge and understanding of chemistry with some general effectiveness.

D Prepares the outline of one or more chemistry investigations.

Selects and may partly acknowledge one or more sources of information about chemistry or an issue in chemistry.

Uses apparatus and technological tools with inconsistent care and effectiveness and attempts to implement safe and ethical investigation procedures.

Obtains, records, and displays findings of investigations using conventions and formats inconsistently, with occasional accuracy and effectiveness.

Describes basic connections between some data and concepts, and attempts to formulate a conclusion and make a simple prediction that may be relevant.

For some procedures, identifies improvements that may be made.

Applies some evidence to describe some basic problems and identify one or more simple solutions, in familiar contexts.

Attempts to use some chemical terms, conventions, formulae, and equations that may be appropriate.

Attempts individual work inconsistently, and contributes superficially to aspects of collaborative work.

Demonstrates some basic knowledge and partial understanding of chemistry concepts.

Identifies and explains some chemistry information that is relevant to one or more social or environmental issues.

Communicates basic information to others using one or more formats.

E Identifies a simple procedure for a chemistry investigation.

Identifies a source of information about chemistry or an issue in chemistry.

Attempts to use apparatus and technological tools with limited effectiveness or attention to safe or ethical investigation procedures.

Attempts to record and display some descriptive information about an investigation, with limited accuracy or effectiveness.

Attempts to connect data with concepts, formulate a conclusion, and make a prediction.

Acknowledges the need for improvements in one or more procedures.

Identifies a basic problem and attempts to identify a solution in a familiar context.

Identifies some chemical terms or formulae.

Shows emerging skills in individual and collaborative work.

Demonstrates some limited recognition and awareness of chemistry concepts.

Shows an emerging understanding that some chemistry information is relevant to social or environmental issues.

Attempts to communicate information about chemistry.

QUESTION 1 Plants under stress produce chemicals. (a) When grass is cut, a series of chemical reactions follow, beginning with the hydrolysis of

triglycerides into fatty acids and alcohol. The structural formula of one such triglyceride is shown below:

(i) Draw the structural formula of the alcohol formed in the hydrolysis of the above triglyceride.

( 2 marks)

(ii) Triglyceride may be hydrogenated under high pressure. (1) State one other reaction conditions used in the hydrogenation process.

(1 mark)

(2) Identify one change that hydrogenation causes in a physical property of a

triglyceride.

(1 mark)

(3) State the structural change in the triglyceride molecule that results in the

change in physical property.

(1 mark)

(iii) The fatty acid is then converted into 2 compounds with the structural formulae

shown below:

Describe a chemical test that can be used to distinguish compound A from

compound B.

(3 marks)

(b) Jasmonic acid is another molecule produced by plants under stress. The structural

formula of jasmonic acid is shown below:

(i) Name the functional group circled in the structural formula above.

(1 mark)

(ii) Jasmonic acid undergoes addition reaction. (1) Draw the structural formula of the product formed when Jasmonic acid

undergoes an addition reaction with bromine.

(2 marks)

(2) State the observation in part (ii)(1) above.

(2 marks)

(iii) Predict and explain the solubility of jasmonic acid in water.

(3 marks)

TOTAL: 16 marks

QUESTION 2 (a) Compound X below is responsible for the odour of Cheddar Cheese:

Compound X

(i) State the systematic name of compound X.

(2 marks)

(ii) Compound X is a weak acid.

Write an equation to show the ionization of compound X in water.

(2 marks) (iii) Compound X oxidises from an aldehyde. Draw the structural formula of this aldehyde.

(2 marks)

(b) Compound Y is responsible for the flavour in Brie Cheese. Compound Y can be made by oxidising alcohol P as shown below:

Compound Y

(i) State the whether alcohol P is classified as primary, secondary or tertiary.

(1 mark)

(ii) An acidified solution containing a manganese anion is the reagent used in the laboratory

to oxidise alcohol P to compound Y. (1) Name the manganese anion used.

(1 mark)

(2) State the conditions required to synthesise compound Y.

(2 marks)

(iii) A student mixed 1 mL of Tollens’ Reagent with 5 drops of Compound Y in a test tube.

Predict the observation for this reaction.

(1 mark)

(c) Ascorbic acid and ethyl pentanoate are two esters that are often used as flavoring agent. The structural formula of ascorbic acid is shown below:

Ascorbic acid

(i) Draw the structural formula of ethyl pentanoate.

(2 marks) (ii) Ascorbic acid is heated with NaOH solution.

Draw the structural formula of the product(s) formed after this reaction.

(3 marks) TOTAL: 16 marks

QUESTION 3 Cellulose is found in plant cell. Cellulose is tasteless, odourless, hydrophilic, insoluble in water and most organic solvents. It can be broken down chemically into its glucose units by treating it with concentrated acids at high temperature.

(a) Draw the structural formula of one glucose molecule from which cellulose is produced.

(2 marks)

(b) Write a balanced equation to show how cellulose is broken down to form dissacharide.

(2 marks)

(c) Glucose produced by the breakdown of cellulose can be converted into ethanol by fermentation with the help of enzyme zymase.

(i) Write an equation to show the production of ethanol by the fermentation of glucose.

(2 marks)

(ii) Explain why combustion of ethanol produced from fermentation will not add more CO2 into the atmosphere.

(1 mark)

(iii) State one condition required for fermentation process, other than yeast to provide zymase

enzyme.

(1 mark)

(iv) After fermentation process, the mixture containing ethanol is decant into a reaction flask

and purification process is carried out using distillation set-up as shown below:

Discuss by referring to one mistake in this distillation set-up and how it can affect the pure

ethanol collected.

(2 marks)

(d) Predict and discuss the solubility between compound P and compound Q.

compound P compound Q

(3 marks)

TOTAL: 13 marks

QUESTION 4 (a) Saccharin, an artificial sweetener, is used to sweeten products such as drinks, candies,

cookies, medicines and toothpastes.

saccharin (i) Give the molecular formula of saccharin.

(2 marks)

(ii) Name the functional group circled on the diagram above.

(1 mark)

(iii) Saccharin is refluxed with diluted HCl solution. (1) Name the type of reaction between saccharine and HCl solution

(1 mark)

(2) Draw the structural formula of the product formed after the reflux.

(2 marks)

(iv) Saccharin is usually used in the form of its sodium salt.

Explain why the usage of sodium salt of saccharin is more favourable than its

molecular form in manufacturing soft drinks.

(2 marks)

(b) The diagram below shows a section of a polypeptide chain.

(i) Polypeptide chain can be broken down by protease (a digestive enzyme) into many amino acids.

(1) State the number of amino acids used to construct this section of the

polypeptide chain.

(1 mark)

(2) Draw the structural formula of one of the amino acid formed after the polypeptide chain is broken down by protease (a digestive enzyme that splits proteins).

(2 marks) (ii) The polypeptide interacts with another polypeptide chain adjacent to it.

(1) Name the type of interaction formed between the side groups circled on the

diagram.

(1 mark)

(2) State the type of structure in which the interaction in part (1) contribute to the

polypeptide (primary, secondary, tertiary, quaternary).

(1 mark)

TOTAL: 13 marks

QUESTION 5 (a) The types of sugar present in an orange juice sample can be separated and identify by TLC

using ethanol as the solvent and octadecylsilane as the stationary phase. One chromatogram is shown in the diagram below:

(i) State how many types of sugar present in this orange juice sample.

(1 mark)

(ii) On the diagram, indicate solvent front. (1 mark) (iii) Explain why this analysis is not effective, and suggest an improvement to this

analysis.

(2 marks)

Credit will be given for answers to part (b), which show clear well-expressed ideas, and which present accurate and relevant information in a well-organised, logical manner. Your answer should be confined to the space provided and should take approximately 10 minutes.

(b) Benzoic acid, benzyl alcohol and benzaldehyde present in an organic sample can be separated and identify by Gas Chromatography using a column packed with inert solids that are coated with high boiling point hydrocarbon and helium as the carrier gas. The structural formula of benzoic acid, benzyl alcohol and benzaldehyde are shown below:

benzoic acid benzyl alcohol benzaldehyde

The chromatogram obtained is shown in the diagram below:

By referring to the polarities of the three organic compounds, discuss their relative strengths

of attractions for stationary phase and the mobile phase and the relative rates of their movement along the stationary phase. Hence, predict and explain peak A, B and C.

(8 marks)

TOTAL: 12 marks

You may write on this page if you need more space to finish your answers to this Question Booklet. Make sure to label each answer carefully (eg.3(e)continued).