T1-2P2 [156 marks]

1a. [1 mark]

Alkenes, alcohols and esters are three families of organic compounds with many commercial uses.

State what is meant by the term stereoisomers.

1b. [4 marks]

An ester which gives apples their characteristic smell contains C, H and O. When of this ester were completelycombusted, of and of were produced.

Determine the empirical formula of the ester, showing your working.

3.00 × 10−3 g6.93 × 10−3 g CO2 2.83 × 10−3 g H2O

−1

1c. [1 mark]The molar mass of the ester is . Determine its molecular formula.116.18 gmol−1

1d. [2 marks]2-bromobutane is optically active. Draw the two enantiomers of 2-bromobutane and compare their physical and chemicalproperties.

2a. [9 marks]

An organic compound, X, with a molar mass of approximately contains 54.5% carbon, 36.3% oxygen and 9.2% hydrogen bymass.

(i) Distinguish between the terms empirical formula and molecular formula.

Empirical formula:

Molecular formula:

(ii) Determine the empirical formula of X.

(iii) Determine the molecular formula of X.

(iv) X is a straight-chain carboxylic acid. Draw its structural formula.

(v) Draw the structural formula of an isomer of X which is an ester.

(vi) The carboxylic acid contains two different carbon-oxygen bonds. Identify which bond is stronger and which bond is longer.

Stronger bond:

Longer bond:

88 g mol−1

2b. [5 marks](i) State and explain which of propan-1-ol, , and methoxyethane, , is more volatile.

(ii) Propan-1-ol, , and hexan-l-ol, , are both alcohols. State and explain which compound is moresoluble in water.

CH3CH2CH2OH CH3OCH2CH3

CH3CH2CH2OH CH3(CH2)4CH2OH

2c. [6 marks]Graphite is used as a lubricant and is an electrical conductor. Diamond is hard and does not conduct electricity. Explain thesestatements in terms of the structure and bonding of these allotropes of carbon.

Graphite:

Diamond:

3. [1 mark]Which represents an empirical formula?

A.

B.

C.

D.

C2H4

B2H6

Al2O3

C6H6

4. [1 mark]Which statements are correct about Avogadro’s constant?

I. It is the number of ions in 12 g of sodium hydride, NaH.

II. It is the number of molecules in of hydrogen gas at 0 °C and 1 atm.

III. It is the number of atoms in 12 g of .

A. I and II only

B. I and III only

C. II and III only

D. I, II and III

22.4 dm3

12C

−1

5. [1 mark]What is the molar mass, in , of a substance if 0.30 mol of the substance has a mass of 18 g?

A. 5.4

B. 6.0

C. 30

D. 60

g mol−1

6. [1 mark]Which contains the largest number of ions?

A. 1 mol of

B. 1 mol of

C. 2 mol of

D. 3 mol of

Al2(SO4)3

Mg3(PO4)2

K3PO4

NaNO3

7. [1 mark]Which is the best description of relative atomic mass, A ?

A. The number of neutrons and protons present in the nucleus of an atom

B. The average number of neutrons and protons in all isotopes of an element

C. The weighted mean mass of naturally occurring isotopes of an element compared to the mass of an atom of carbon-12

D. The weighted mean mass of naturally occurring isotopes of an element compared to 1/12 of the mass of an atom of carbon-12

r

th

8a. [2 marks]

A student decided to determine the molecular mass of a solid monoprotic acid, HA, by titrating a solution of a known mass of the acid.

The following recordings were made.

Calculate the mass of the acid and determine its absolute and percentage uncertainty.

8b. [3 marks]This known mass of acid, HA, was then dissolved in distilled water to form a solution in a volumetric flask. A sample of this solution reacted with of a NaOH solution. Calculate the molar mass of the acid.

100.0 cm3 25.0 cm3

12.1 cm3 0.100 moldm−3

8c. [2 marks]The percentage composition of HA is 70.56% carbon, 23.50% oxygen and 5.94% hydrogen. Determine its empirical formula.

8d. [1 mark]A solution of HA is a weak acid. Distinguish between a weak acid and a strong acid.

8e. [2 marks]Describe an experiment, other than measuring the pH, to distinguish HA from a strong acid of the same concentration and describewhat would be observed.

9a. [2 marks]

A student decided to determine the molecular mass of a solid monoprotic acid, HA, by titrating a solution of a known mass of the acid.

The following recordings were made.

Determine the molecular formula of HA.

9b. [2 marks]

To investigate the effect of temperature on the effectiveness of a buffer solution, the student placed of the buffer solution in awater bath at 24 °C. He added small portions of hydrochloric acid, stirring after each addition, until a total of was added, andmeasured the pH continuously during the addition. The procedure was repeated at different temperatures and the results are shown inthe following graph.

State what is meant by a buffer solution.

20.0 cm3

10 cm3

9c. [2 marks]With reference to the graph on page 4, describe the effect of increasing temperature on the effectiveness of the buffer solution.

10a. [2 marks]

Cortisone is a therapeutic drug whose three-dimensional structure is represented below.

Identify the names of two functional groups present in cortisone.

1.

2.

[1 mark]10b. Draw a circle around each of these two functional groups in the structure above and label them 1 and 2 as identified in (a) (i).

10c. [1 mark]Describe what is meant by the term structural isomers.

10d. [1 mark]

P

Apply IUPAC rules to state the name of P.

10e. [1 mark]X is a straight-chain structural isomer of P. Draw the structure of X.

10f. [2 marks]

10g. [1 mark]Identify a suitable catalyst used in the reaction to form R.

10h. [4 marks]P, CH CH=CHCH , reacts with HBr to form CH CHBrCH CH . Suggest one suitable mechanism for the reaction ofCH CHBrCH CH with aqueous sodium hydroxide, using curly arrows to represent the movement of electron pairs.

3 3 3 2 3

3 2 3

10i. [1 mark]State the structural formula of the organic product formed, S, when Q is heated under reflux with acidified potassium dichromate(VI).

10j. [1 mark]Apply IUPAC rules to state the name of this product, S.

10k. [1 mark]P can undergo a polymerization reaction. Draw two repeating units of the resulting polymer.

10l. [3 marks]

Menthol can be used in cough medicines. The compound contains 76.84% C, 12.92% H and 10.24% O by mass.

Determine its empirical formula.

10m. [1 mark]Determine its molecular formula given that its molar mass is .M = 156.30 g mol−1

11a. [1 mark]

Geometrical isomerism and optical isomerism are two sub-groups of stereoisomerism in organic chemistry.

Describe what is meant by the term stereoisomers.

11b. [1 mark]Geometrical isomers have different physical properties and many drugs, such as doxepin (which has antidepressant properties),have geometrical isomers.

For each of the carbon atoms labelled 1 and 2 in doxepin, deduce the type of hybridization involved (sp, sp or sp ).

1:

2:

2 3

11c. [1 mark]Clomifene, a fertility drug, whose three-dimensional structure is represented below, also has geometrical isomers.

Identify the name of one functional group present in clomifene.

11d. [2 marks]

Compound P has the following three-dimensional structure. P also has geometrical isomers.

Draw any two other isomers of P.

11e. [2 marks]Apply IUPAC rules to state the names of all the straight-chain isomers of compounds of molecular formula C H (including P).4 8

11f. [4 marks]State the structural formula of the organic products, Q, R, S and T, formed in the following reactions.

11g. [1 mark]State the structural formula of the organic product formed, U, when R is heated under reflux with acidified potassiumdichromate(VI).

11h. [1 mark]Apply IUPAC rules to state the name of this product, U.

11i. [4 marks]

Menthol can be used in cough medicines. The compound contains C, H and O only.

When a of the compound was combusted, of carbon dioxide and of water wereproduced. Determine the molecular formula of the compound showing your working, given that its molar mass is .

6.234 × 10−2 g 1.755 × 10−1 g 7.187 × 10−2 gM = 156.30 g mol−1

11j. [1 mark]Menthol occurs naturally and has several isomers. State the structural feature of menthol which is responsible for it havingenantiomers.

11k. [1 mark]State the instrument used to distinguish between each of the two enantiomers, and how they could be distinguished using thisinstrument.

11l. [2 marks]Compare the physical and chemical properties of enantiomers.

Physical properties:

Chemical properties:

12. [1 mark]The structural formula of a dioxin is shown below.

What is its empirical formula?

A.

B.

C.

D.

C6O

C6H4O

C6H6O

C12H8O2

13. [1 mark]What is the mass, in g, of one mole of hydrated copper(II) sulfate, , given the following relative atomic mass values?

A. 160

B. 178

C. 186

D. 250

CuSO4 ∙ 5H2O

14. [1 mark]For which compounds is the empirical formula the same as the molecular formula?

I. Methane

II. Ethene

III. Ethanol

A. I and II only

B. I and III only

C. II and III only

D. I, II and III

15a. [1 mark]

The open-chain structure of D-fructose is shown below.

State the names of two functional groups in D-fructose.

15b. [1 mark]Deduce the empirical formula of D-fructose.

15c. [2 marks]Calculate the percentage composition by mass of D-fructose.

15d. [2 marks]State a balanced equation for the complete combustion of D-fructose.

16. [3 marks]

Magnesium has three stable isotopes, , and . The relative abundance of each isotope is 78.99%, 10.00% and 11.01%respectively, and can be determined using a mass spectrometer.

(i) Define the term relative atomic mass.

(ii) Calculate, showing your working, the relative atomic mass, , of magnesium, giving your answer to two decimal places.

24Mg 25Mg 26Mg

Ar

17. [2 marks]

Magnesium has three stable isotopes, , and . The relative abundance of each isotope is 78.99%, 10.00% and 11.01%,respectively, and can be determined using a mass spectrometer.

Calculate, showing your working, the relative atomic mass, , of magnesium, giving your answer to two decimal places.

24Mg 25Mg 26Mg

Ar

18a. [3 marks]

A class studied the equilibrium established when ethanoic acid and ethanol react together in the presence of a strong acid, usingpropanone as an inert solvent. The equation is given below.

One group made the following initial mixture:

The density of ethanoic acid is . Determine the amount, in mol, of ethanoic acid present in the initial mixture.

CH3COOH + C2H5OH ⇌ CH3COOC2H5 + H2O

1.05 gcm−3

18b. [3 marks]The concentration of ethanoic acid can be calculated as . Determine the percentage uncertainty of this value.(Neglect any uncertainty in the density and the molar mass.)

1.748 moldm−3

18c. [1 mark]

After one week, a sample of the final equilibrium mixture was pipetted out and titrated with aqueoussodium hydroxide to determine the amount of ethanoic acid remaining. The following titration results were obtained:

Calculate the absolute uncertainty of the titre for Titration 1 ( ).

5.00 ± 0.05 cm3 0.200 moldm−3

27.60 cm3

18d. [1 mark]Suggest the average volume of alkali, required to neutralize the sample, that the student should use.5.00 cm3

18e. [1 mark]Deduce the equilibrium constant expression for the reaction.

18f. [1 mark]The other concentrations in the equilibrium mixture were calculated as follows:

Use these data, along with your answer to part (iii), to determine the value of the equilibrium constant. (If you did not obtain an answer to part(iii), assume the concentrations of ethanol and ethanoic acid are equal, although this is not the case.)

18g. [1 mark]Outline how you could establish that the system had reached equilibrium at the end of one week.

18h. [1 mark]Outline why changing the temperature has only a very small effect on the value of the equilibrium constant for this equilibrium.

18i. [2 marks]Outline how adding some ethyl ethanoate to the initial mixture would affect the amount of ethanoic acid converted to product.

18j. [2 marks]Propanone is used as the solvent because one compound involved in the equilibrium is insoluble in water. Identify this compoundand explain why it is insoluble in water.

18k. [1 mark]Suggest one other reason why using water as a solvent would make the experiment less successful.

19a. [1 mark]

Organic compound X is 68.11% carbon, 13.74% hydrogen and 18.15 % oxygen by mass.

Show that the empirical formula of compound X is .C5H12O

19b. [11 marks]The mass spectrum, infrared spectrum and details of the spectrum of compound X are given below.

Mass spectrum:

Infrared spectrum:

spectrum:

Analyse these three spectra and, using relevant information, deduce the identity of the compound.

Mass spectrum:

1H NMR

1H NMR

Infrared spectrum:

spectrum:

Identity of X:

1H NMR

20. [1 mark]Which sample contains the largest amount, in mol, of oxygen atoms?

A. 0.20 mol

B. 0.30 mol

C. 0.40 mol

D. 0.80 mol

P2O5

O3

CH3COOH

H2O

21. [1 mark]Which compound has the highest percentage of carbon by mass?

A.

B.

C.

D.

CH4

C2H4

C4H10

C6H6

22. [1 mark]What is the total number of protons and electrons in one mole of hydrogen gas?

A. 2

B. 4

C.

D.

1.2 × 1024

2.4 × 1024

23. [1 mark]A hydrocarbon contains 85.7 % carbon by mass. What is the empirical formula of the hydrocarbon?

A.

B.

C.

D.

C2H3

CH2

C2H5

CH3

24a. [4 marks]A hydrocarbon has the empirical formula . When 1.17 g of the compound is heated to 85 °C at a pressure of 101 kPa itoccupies a volume of .

(i) Calculate the molar mass of the compound, showing your working.

(ii) Deduce the molecular formula of the compound.

C3H7

400 cm3

24b. [2 marks] exists as three isomers. Identify the structure of the isomer with the lowest boiling point and explain your choice.C5H12

24c. [2 marks]Ethanol is a primary alcohol that can be oxidized by acidified potassium dichromate(VI). Distinguish between the reactionconditions needed to produce ethanal and ethanoic acid.

Ethanal:

Ethanoic acid:

24d. [2 marks]Determine the oxidation number of carbon in ethanol and ethanal.

Ethanol:

Ethanal:

24e. [1 mark]Deduce the half-equation for the oxidation of ethanol to ethanal.

24f. [2 marks]Deduce the overall redox equation for the reaction of ethanol to ethanal with acidified potassium dichromate(VI) by combining youranswer to part (c) (iii) with the following half-equation:

Cr2O2−7 (aq) + 14H+(aq) + 6e− → 2Cr3+(aq) + 7H2O(l)

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24g. [2 marks]Describe two characteristics of a reaction at equilibrium.

24h. [2 marks]Describe how a catalyst increases the rate of a reaction.

24i. [2 marks]State and explain the effect of a catalyst on the position of equilibrium.