Carboxylic AcidsCnH2n+1COOH

Fermentation of sugars is one method of making ethanol. Vines produce

glucose by photosynthesis. The glucose collects in the grapes which grow

in clusters on the vine.

(a) The grapes are crushed to extract an aqueous solution of glucose. This

solution is fermented to make ethanol. Explain why each of the following is

necessary.

(i) Yeast

(ii) An absence of oxygen

(iii) An optimum temperature of about 37 °C

(d) Plants can make esters as well as sugars. The formula of a typical ester

is drawn below.

Deduce the names of the organic acid and of the alcohol from which the

ester could have been made

organic acid

alcohol

1 The structures of three compounds are shown.

What are X, Y and Z?X Y Z

ABCD

alkanealkanealkenealkene

alkenealkenealkanealkane

alcoholcarboxylic acidalcoholcarboxylic acid

2 Some students are asked to draw the structure of propanol.Which diagram should the students draw?

3 Which two compounds have molecules in which there is a double bond?A ethane and ethanoic acidB ethane and ethanolC ethene and ethanoic acidD ethene and ethanol

4 In the molecule shown, the two –OH groups are numbered.

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Which of these –OH groups react with aqueous sodium hydroxide?

5 The structures of three compounds are shown.

What are X, Y and Z?

6 A compound, X, has a molecular formula C4H8O2 and can be prepared by the reactions shown. Ethanol oxidation Y + ethanol XWhat is the structural formula of X ?A HCO2CH2CH2CH3

B CH3CO2CH2CH3

C CH3CH2CO2CH3

D CH3CH2CH2CO2H

7 In ripe fruit, the conversion of sugars into alcohol can occur naturally.What is the name of this process?A additionB crackingC fermentationD polymerisation

8 The results of tests on compound Z are shown.

test resultadd bromine water

add aqueous sodium carbonateturns colourless

carbon dioxide formed

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What is the compound Z ? H H H O

A H C C C C O H

H H H

H H H

B H C C C O H

H H H

H H H

C H C C C O H

H

H H H O

D H C C C C O H

H 9 How many oxygen atoms and double bonds are there in one molecule of ethanoic acid?

10 Which formula represents a compound that will react with sodium carbonate to give off carbon dioxide?A CH3OHB HCO2CH3

C CH3CO2HD CH3CO2C2H5

11 Which compound is ethanol?

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12 Compound X has the molecular formula C2H6O.• X can be made by a fermentation process.• X can be oxidised to Y.• X can react with Y to form Z and water.To which homologous series do X, Y and Z belong?

13 Which structure shows a compound that reacts with ethanol to give a sweet-smelling liquid?

14 A vegetable oil is polyunsaturated.Which statement about this vegetable oil is correct?A It has double bonds between carbon and hydrogen atoms.B It reacts with hydrogen to form a solid compound.C It reacts with steam to form margarine.D It turns aqueous bromine from colourless to brown.

15 The displayed formulae of two compounds are shown.

What are the similarities and differences between the two compounds?

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16 When ethanol reacts with ethanoic acid, the ester ethyl ethanoate is formed. C2H5OH + CH3CO2H → CH3CO2C2H5 + H2O

What is the formula of the ester formed when methanol reacts with butanoic acid (C3H7CO2H)?A C2H5CO2C2H5

B C3H7CO2C2H5

C CH3CO2C3H7

D C3H7CO2CH3

17 The list shows reactions in which ethanol is either a reactant or a product.

In which reactions is water also either a reactant or a product?A 1, 3 and 4 onlyB 2, 3 and 4 onlyC 1, 2 and 4 onlyD 3 only

18 Which compound is unsaturated and forms a neutral solution in water?

19 The apparatus shown may be used to study the products of fermentation.

What is the purpose of the aqueous calcium hydroxide?

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A to absorb any excess of yeastB to condense the ethanol producedC to prevent air entering the systemD to show that carbon dioxide is produced

20 Which two compounds have molecules in which there is a double bond?A ethane and ethanoic acidB ethane and ethanolC ethene and ethanoic acidD ethene and ethanol

21 How many oxygen atoms and double bonds are there in one molecule of ethanoic acid?

22 The structural formula of butenedioic acid is shown.

Which statement about butenedioic acid is not correct?

A It decolourises aqueous bromine.B Its aqueous solution reacts with sodium carbonate.C Its empirical formula is the same as its molecular formula.D Its relative molecular mass is 116.

23 The tables shows the properties of four compounds.Which compound could be ethanoic acid?

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24 The table shows the results of tests carried out on compound X.

Which formula represents compound X?

25 What is the general formula of the homologous series of carboxylic acids?methanoic acid HCO2Hethanoic acid CH3CO2Hpropanoic acid C2H5CO2Hbutanoic acid C3H7CO2H

A CHOB CnH2nOC CnHnOn

D CnH2nO2

26 An organic compound, Y, reacts with sodium hydroxide to give a compound with formula C3H5O2Na.What is compound Y?

A ethanolB propaneC propanoic acidD propanol

27 The tables shows the properties of four compounds.Which compound could be ethanoic acid?

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28 The displayed formulae of two compounds are shown.

What are the similarities and differences between the two compounds?

29 When ethanol reacts with ethanoic acid, the ester ethyl ethanoate is formed.C2H5OH + CH3CO2H ¨ CH3CO2C2H5 + H2OWhat is the formula of the ester formed when methanol reacts with butanoic acid (C3H7CO2H)?

A C2H5CO2C2H5

B C3H7CO2C2H5

C CH3CO2C3H7

D C3H7CO2CH3

30 What is the catalyst used in the preparation of ethyl ethanoate from ethanol and ethanoic acid?

A concentrated sulphuric acidB nickelC vanadium(V) oxideD yeast

31 A compound, X, has a molecular formula C4H8O2 and can be prepared by the reactions shown.

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What is the structural formula of X?

A HCO2CH2CH2CH3

B CH3CO2CH2CH3

C CH3CH2CO2CH3

D CH3CH2CH2CO2H

32 The results of tests on compound Z are shown.

What is compound Z?

33 A liquid reacts with each of sodium carbonate, potassium hydroxide and ethanol.What is the liquid?

A aqueous ammoniaB ethanoic acidC ethyl ethanoateD hydrochloric acid

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Lets find answers to paper 2 and paper 4 !

1 All members of the carboxylic acid homologous series contain the –CO2H group. The table shows the formula of the first three members of this homologous series.

(a) Name the unbranched carboxylic acid that has four carbon atoms per molecule. [1](b) Give the formula of the sixth member of the carboxylic acid homologous series. [1](c) Ethanol, C2H5OH, reacts with ethanoic acid to make ethyl ethanoate.Draw the structure of ethyl ethanoate. [1](d) Name a reagent that can be used to convert ethanol into ethanoic acid. [1](e) Magnesium reacts with ethanoic acid to make magnesium ethanoate and hydrogen.Write the equation for this reaction. Use the equation to calculate the mass ofmagnesium needed to react completely with 50 cm3 of 1.0 mol/dm3 of ethanoic acid. [3] (f) Suggest why the reaction between magnesium and 1.0 mol/dm3 ethanoic acid is muchslower than the reaction between magnesium and 1.0 mol/dm3 hydrochloric acid [2](g) Aqueous sodium hydroxide neutralises dilute ethanoic acid.Write the ionic equation for this reaction. [1]

-------------------------------------------------2 This table shows some information about two homologous series; the alkanes and the acid chlorides.

Use the information in the table to answer the following questions.(a) Name the acid chloride with the highest boiling point. [1]

(b) Deduce the name of the acid chloride with the formula C2H5COCl. [1] (c) The general formula for alkanes is CxH(2x + 2).

Deduce the general formula for acid chlorides. [1] (d) (i) Name the products of the complete combustion of an alkane.(ii) Would you expect the products of complete combustion of the acid chlorides to bethe same as in (i)? Explain your reasoning. [2]

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3 This is the structure of an ester made in a reversible reaction between a carboxylic acid and an alcohol.

(a) (i) State the conditions for this reaction. [2] (ii) Draw the structure of the carboxylic acid used in the reaction. [1] (iii) Write an equation for this reaction. [2](b) A student carried out some experiments to compare the relative strengths of diluteethanoic acid with dilute hydrochloric acid.(i) Describe a test that can be used to distinguish between dilute ethanoic acid anddilute hydrochloric acid. [2] (ii) Name a solid substance that will react with both acids. Describe what you will seeduring the reaction. [2]substance observations --------------------------------------------------------------

4 The table gives information about the first five members of the homologous series of carboxylic acids.

(a) (i) Predict the formula and the relative molecular mass for pentanoic acid.(ii) Explain why it is easier to predict the boiling point of pentanoic acid than the meltingpoint. [3] (b) Draw the displayed formula for propanoic acid. [1](c) Analysis of an organic acid isolated from red ants shows that it contains 0.060 g of carbon, 0.010g of hydrogen and 0.16 g of oxygen.Calculate the empirical formula for this acid. [2](d) Ethanoic acid reacts with magnesium oxide.Name the products formed and write a balanced equation for the reaction. [2](e) Describe how ethanoic acid can be converted into ethyl ethanoate. [2]

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5 The structures of three organic molecules are shown below.

(a) Describe an industrial process to make ethanol from ethene. [3]

(b) Name a reagent that can be used to convert ethanol into ethanoic acid. [1](c) Ethanol and concentrated ethanoic acid react to form the ester ethyl ethanoate.(i) Name the other product formed.(ii) Name the catalyst used in this reaction.(iii) The reaction between ethanol and ethanoic acid can reach dynamic equilibrium.What is meant by the term dynamic equilibrium? [4](d) Ethanoic acid is a weak acid. It reacts with magnesium giving a gas and a magnesium salt.(i) What is meant by the term weak acid? (ii) Name the gas formed.(iii) What is the formula of the magnesium salt formed? [3]

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12 Some organic compounds found in ripe fruits are shown below.

(a) What do you understand by the term organic compound? [1]

……………………………………………………………………………………………………….……………………………………………………………………………………………………….

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(b) Which two of the compounds belong to the same homologous series?

compound …………………………and compound …………………………………………[1]

(c) Which one of these compounds is an unsaturated hydrocarbon? [1]

………………………………………………………………………………………………………

(d) Which one of these compounds is an alcohol?

……………………………………………………………………………………………………[1]

(e) Which one of these compounds can be formed directly by cracking the paraffin

fraction from petroleum?

................................................................................................................... [1](f) Compound D burns readily.(i) Burning is an exothermic reaction.Explain the meaning of the term exothermic.

……………………………………………………………………………………………………[1]

(ii) State the products formed when D burns in excess air.

……………………………………………………………………………………………………A

(iii) Name the carbon compound formed when D undergoes incomplete combustion.

……………………………………………………………………………………………………[1](g) Write down the molecular formula of compound C.

……………………………………………………………………………………………………[1]

(h) Calculate the relative molecular mass of compound C.

……………………………………………………………………………………………………[1]

(i) Many fruits contain a variety of different coloured compounds.What separation technique can you use to separate these different colouredcompounds?

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...........................................................................................................................

..............[1]

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Put a ring around the hydroxyl group Put a ring around the double bond

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15 Both ethanoic acid and butanoic acid are found in some plants and bacteria. (a) Draw the structure of butanoic acid showing all atoms and bonds . (b) Explain;

(i) Whatis meant by a weak acid?(ii) How you could show that butanoic acid is a weak acid.

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(c) Butanoic acid can be converted into an ester by heating it with an alcohol and a few drops of concentrated sulphuric acid. A sample of an ester contains 0.18 g carbon, 0.03g of hydrogen and 0.08g of oxygen, The relative molecular mass of the ester is 116. Calculate both the empirical and molecular formulae of this ester. (d) Ethanoic acid can be produced by the bacterial fermentation of C6H12O6. During this process glucose is first oxidized to ethanol. (i) Write anequation for the fermentation of glucose to form ethanol and carbon dioxide. (ii) state the reagents and conditions required for ethanol to be oxidized to ethanoic acid in the laboratory.

16 Propanoic acid, C2H5COOH, is a weak acid. (a) Propanoic acid reacts with sodium carbonate.Write the equation for this reaction. (b) Magnesium reacts with propanoic acid to form magnesium proanoate and hydrogen. Mg + 2C2H5COOH (C2H5COO)2Mg + H2

A tudent added 4.80 g of magnesium to 30.0g of propanoic acid. (i) Which one of these reactants, magnesium or propanoic acid,is in excess? Explain uour answer. (ii) Calculate both the number of moles of hydrogen and the volume of hydrogen formed at r.t.p.

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