Heinemann Practice Exam 1 Unit 3 & 4.pdf

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Practice exam 1VCE Chemistry Units 3 & 4

Rehearse and remember

Copyright Pearson Australia 2010 (a division of the Pearson Australia Group Pty Ltd) 1

VCE Chemistry Units 3 & 4

Practice exam 1

Reading time: 15 minutes

Writing time: 1 hour 30 minutes

Section Number of questions Number of

questions to be answered

Number of marks Suggested times (minutes)

A 20 20 20 30 B 6 6 56 60 Total 76 90

Disclaimer This is a practice examination. It represents Pearson Educations view only of what would be useful preparation material for the externally assessed examination.

Copyright Pearson Australia 2010 (a division of the Pearson Australia Group Pty Ltd 2

Section A Multiple-choice questions

Instructions for Section A Answer all questions in pencil on the answer sheet provided for multiple-choice questions. Choose the response that is correct or that best answers the question. A correct answer scores 1; an incorrect answer scores 0. Marks will not be deducted for incorrect answers. No marks will be given if more than one answer is completed for any question. The chemistry data book should be used with this exam.

Questions 1 and 2 refer to the following information. 20.0 g of sulfur reacts exactly with 20.0 g of oxygen gas to form a compound. Question 1 The empirical formula of the compound formed is: A S2O B SO C SO2 D SO3 Question 2 The number of atoms in the product formed will be: A 3 B 0.625 6.02 1023 C 0.625 6.02 1023 3 D 6.02 1023 3 Question 3 A beaker contains 10 mL of 0.1 M Na2SO4. The number of mole of ions in the beaker is: A 0.001 mol B 0.003 mol C 0.1 mol D 0.2 mol Question 4 In which compound or ion does the underlined element have the same oxidation number as chromium has in Cr2O3? A Al2O3 B NH3 C SO2 D MnO4


Question 5 20.0 mL aliquots of 0.1 M sodium hydroxide (NaOH) solution are titrated against a diprotic acid. The average titre obtained is 10.0 mL. The concentration of the acid is: A 0.025 M B 0.050 M C 0.075 M D 0.10 M Question 6 Select the correct statement from the following: A An indicator should lead to an end point that matches the equivalence point. B Acidbase indicators will change colour at pH 7 when the acid and base have neutralised each

other. C Phenolphthalein is a good indicator for all titrations because its colour change is so distinctive. D An indicator should change colour when the amount of acid equals the amount of base. Question 7 Four beakers contain samples of acid as described below: 1 mL of 0.0001 M HCl 0.5 mL of 2.0 M HCl 2500 mL of 5.0 M HCl 2500 mL of 0.001 M HCl

Beaker A Beaker B Beaker C Beaker D Which contents of which beaker will have the highest pH? A A B B C C D D Question 8

Which of A, B, C or D contains the greatest number of chlorine ions or atoms? A A B B C C D D


Question 9 How many peaks, other than the reference peak, will the following molecule have on 1H NMR spectroscopy?

A 1 B 2 C 3 D 12 Question 10 In the reaction:

NH4+(aq) + S2(aq) NH3(aq) + HS(aq) A NH4+ acts as a base only B S2 acts as a base only C NH4+ acts as an acid and as an oxidant D NH3 acts as an acid only. Question 11 A visible spectrum for an ionic solution is shown below.

From this spectrum, it can be concluded that: A the substance probably contains a hydroxyl group and a C=O bond B to determine the concentration of the ionic solution, a calibration curve is best constructed by

running standards at 600 nm C the solution strongly absorbs light of wavelength 600 nm D to determine the concentration of the ionic solution, a calibration curve would be constructed by

running standards at either 475 or 750 nm.


Question 12 The molecule shown is known as Dopa. It is used in the treatment of Parkinsons disease.

The functional groups in Dopa are: A hydroxyl, ether and ester B hydroxyl, amine and carboxyl C ester, amide and carboxyl D hydroxyl, carboxyl and amide. Question 13 Propene is reacted with chlorine gas. The molecular formula of the product(s) formed will be: A C3H4Cl2 only B C3H6Cl and C3H5Cl2 C C3H7Cl only D C3H6Cl2 only. Question 14

The molecule shown could be formed from the reaction between: A propanoic acid and ethanol B ethanol and propanoic acid C 1-propanol and methanoic acid D 1-propanol and ethanoic acid. Question 15 Consider the molecule:

The systematic name of the molecule is: A 4-chloro-4-methylpentane B 4-chloro-4-methylhexane C 2-chloro-2-methylpentane D 2-chloro-2-methylhexane.


Question 16

This molecule is the amino acid: A asparagine under acid conditions B lysine under neutral conditions C lysine under base conditions D lysine under acid conditions. Question 17

Molecules A and B are structural isomers. Their chemical properties are similar and it can be difficult to distinguish which molecule is which. If both molecules are subjected to low-resolution NMR spectroscopy, the number of peaks on each spectrum will be: Molecule A Molecule B 1H NMR 13C NMR 1H NMR 13C NMR A 1 1 1 1 B 2 2 2 1 C 3 3 1 2 D 5 3 3 3 Question 18 Pick the correct combination in the list below: Building block Reaction type New bond formed

in product Product

A monosaccharides condensation ester sugar B amino acids condensation peptide protein C fatty acid hydrolysis ester lipid D lipid condensation ester fatty acid


Question 19 The base sequence in a particular strand of DNA is shown below:

GGCAATGA The sequence of bases that will pair with this strand is: A AGTAACGG B TTACCGTC C CCGTTACT D CCGAATCA Question 20 Linolenic acid is a fatty acid with the molecular formula C18H32O2. Linolenic acid will have: A one carbon-to-carbon double bond, a polar segment and a non-polar segment B two carbon-to-carbon double bonds and no dipole C all single bonds between carbon atoms and a double bond to an oxygen atom D two carbon-to-carbon double bonds, one carbon-to-oxygen double bond and a

long non-polar segment. END OF SECTION A


Section B Short-answer questions

Instructions for Section B Answer all questions in the spaces provided. To obtain full marks for your responses you should: give simplified answers with an appropriate number of significant figures to all numerical

questions show all working in your answers to numerical questions make sure chemical equations are balanced and that the formulas for individual substances

include an indication of state.

Question 1 Salicylic acid has the structure shown below.

a i What is the name of the hexagonal ring drawn in this structure?

ii Name the two functional groups shown in salicylic acid.

1 + 1 = 2 marks

b The original commercial process for the manufacture of aspirin used the reaction of ethanoic

acid and the hydroxyl group on salicylic acid. i Draw a structural formula for ethanoic acid.

ii Draw a structural formula for aspirin. (The same hexagonal representation can be used.)

iii What other molecule is produced in this reaction?

1 + 1 + 1 = 3 marks


c Salicylic acid can also be used to manufacture the compound oil of wintergreen. In this process methanol reacts with the carboxyl group on salicylic acid. i Draw a structural formula for oil of wintergreen.

ii Name the functional group formed in this reaction.

1 + 1 = 2 marks

Total 7 marks

Question 2 The triglyceride made from oleic acid would have the structure shown.

a i Circle all occurrences of the ester functional group.

ii Is the fatty acid saturated or unsaturated?

1 + 1 = 2 marks

b The first step in the production of biodiesel from this lipid is hydrolysis. i Draw the two molecules formed from hydrolysis of this lipid.

ii The fatty acid formed is reacted with methanol to form biodiesel. Draw the biodiesel

molecule formed.


iii Write a balanced equation for the complete combustion of this biodiesel molecule.

2 + 1 + 2 = 5 marks

Total 7 marks Question 3

The molecule C3H6 can form two isomers when it reacts with hydrochloric acid. a Use the spaces below to name and draw structural diagrams of the molecules AD.

A

Name: B

Name: C

Name: D

Name:

4 marks


b Name the type of reaction that is responsible for:

i C3H6 A ______________________________________________________________ ii A C _________________________________________________________________ iii C D _________________________________________________________________

1 + 1 + 1 = 3 marks c Samples of A and B can be separated in a laboratory by cooling the mixture to liquefy both

components and then allowing the temperature to increase. Explain how distillation separates the two compounds.

2 marks

d Molecule D is passed through a mass spectrometer.

i What is the mass of the parent molecular ion? ___________________________________ ii Suggest two peaks that this molecule might have in a mass spectrum and draw

the fragment that caused each peak. mass _________________________ fragment _________________________________ mass _________________________ fragment _________________________________

1 + 2 = 3 marks e Molecule B is subjected to high-resolution proton NMR spectroscopy.

i Draw the molecule.

ii State how many sets of peaks it will have.

iii Explain the splitting pattern that each peak will exhibit.

2 + 1 + 2 = 5 marks

Total = 17 marks Question 4 A 6.160 g sample of an organic molecule is found to contain 4.000 g of carbon and 0.833 g of hydrogen. a The molecule also contains oxygen. What is the mass of oxygen?

1 mark


b Determine the empirical formula of the molecule.

2 marks

c The mass spectrum of this molecule shows the parent molecular ion has a mass of 74. What is the molecular formula of the molecule?

1 mark

d i An infrared spectrum of the molecule shows a broad band around 3300 cm1. What is this likely to be due to?

ii There is no peak at 1700 cm1.What might this tell you?

iii Draw a possible structure for this molecule.

iv Is this the only possible structure from the information provided so far? Explain your

answer.

1 + 1 + 1 + 1 = 4 marks

Total 8 marks Question 5 A liquid sitting in an unmarked bottle is determined as being acidic. It is not known if the acid is monoprotic or polyprotic. A titration is conducted to determine the concentration of the acid. A 20.0 mL sample of the acid is added to a 250 mL volumetric flask and made up to the mark with distilled water. The diluted acid is added to a burette and titrated against 25.0 mL aliquots of 0.0500 M sodium carbonate (Na2CO3). Methyl orange is used as an indicator and the average titre obtained is 17.8 mL. a Calculate the amount, in mol, of Na2CO3 used in the titration.

1 mark

b The concentration of the acid obtained will depend upon whether the acid is monoprotic or polyprotic.

Complete the table, showing possible concentrations of the acid: If the acid is Concentration of diluted acid Concentration of original acid

monoprotic diprotic triprotic

6 marks


c If the acid is diprotic and represented as H2X, write a balanced equation for its reaction with Na2CO3.

1 mark

d Justify the use of methyl orange as an indicator for this titration.

2 marks

Total 10 marks

Question 6 Beach sand is often a mixture of eroded rock and sea shells. The percentage of each varies with the location of the beach. The percentage of sand that is shell can usually be estimated from its reaction with hydrochloric acid. Shell is mainly calcium carbonate (CaCO3) and the reaction is:

2HCl(aq) + CaCO3(s) CaCl2(aq) + H2O(l) + CO2(g)

A 4.20 g sample of sand is placed in a flask and 40.0 mL of 2.00 M HCl is added to it. After the reaction has finished, the excess HCl is measured by titrating the contents of the flask with 1.00 M NaOH solution. The volume of NaOH required to neutralise the acid in a particular analysis is 24.7 mL. a Write a balanced equation for the reaction between the hydrochloric acid and the sodium

hydroxide.

1 mark

b Calculate the amount, in mol, of NaOH used.

1 mark

c Calculate the amount, in mol, of HCl added to the sample of sand.

1 mark

d Calculate the amount, in mol, of HCl reacting with CaCO3.

1 mark

e Calculate the percentage by mass of calcium carbonate in the sand.

2 marks

f Students repeat this process carefully several times but their results are not consistent. Suggest a reason for this.

1 mark

Total 7 marks END OF SECTION B

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Practice exam 1

Section A Multiple choice

Answer sheet

Fill in the answer sheet by putting a cross in the correct box.

A B C D 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20

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Heinemann Practice Exam 1 Unit 3 & 4.pdf

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