Carboxylic Acids, Fatty 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( anaerobic condition)

(iii) An optimum temperature of about 37 °C

(b) If the presence of oxygen what reactions occurs

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 Which two compounds have molecules in which there is a double bond?A ethane and ethanoic acid C ethane and ethanolB ethene and ethanoic acid D ethene and ethanol

3 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 C CH3CO2CH2CH3

B CH3CH2CO2CH3 D CH3CH2CH2CO2H

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

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

A

B

C

D

5 In ripe fruit, the conversion of sugars into alcohol can occur naturally.What is the name of this process?A addition B cracking C fermentation D polymerisation

6 The results of tests on compound Z are shown.

test resultadd bromine water

add aqueous sodium carbonateturns colourless

carbon dioxide formed

What is the compound Z ?

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

A 1 0B 1 1C 2 0D 2 1

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8 Which formula represents a compound that will react with sodium carbonate to give off carbon dioxide?A CH3OH B HCO2CH3 C CH3CO2H D CH3CO2C2H5

9 Which compound is ethanol?

10 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?X Y Z

A alcohols carboxylic acids estersB alcohols esters carboxylic acidsC carboxylic acids alcohols estersD carboxylic acids esters alcohols

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

12 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.

13 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

14 An organic compound, Y, reacts with sodium hydroxide to give a compound with formulaC3H5O2Na.What is compound Y?A ethanol B propane C propanoic acid D propanol

15 The list shows reactions in which ethanol is either a reactant or a product.1 combustion of ethanol2 conversion of ethene to ethanol3 fermentation of glucose4 oxidation of ethanol to ethanoic acid

In which reactions is water also either a reactant or a product?A 1, 3 and 4 only B 2, 3 and 4 only C 1, 2 and 4 only D 3 only

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16 The displayed formulae of two compounds are shown.

What are the similarities and differences between the two compounds?similarities differences

A molecular formulae reactionsB molecular formulae relative molecular massesC structures molecular formulaeD structures relative molecular masses

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

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

What is the purpose of the aqueous calcium hydroxide?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

19 Which two compounds have molecules in which there is a double bond?A ethane and ethanoic acid B ethane and ethanolC ethene and ethanoic acid D ethene and ethanol

20 A liquid reacts with each of sodium carbonate, potassium hydroxide and ethanol.What is the liquid?A aqueous ammonia B ethanoic acid C ethyl ethanoate D hydrochloric acid

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

compound degree of ionization in water addition of aqueous solution of the compound to magnesium

A high hydrogen producedB high no reactionC low hydrogen producedD low no reaction

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.

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

test resultbromine water addedsodium carbonate added

decolourisedcolourless gas evolved

Which formula represents compound X?

24 What is the general formula of the homologous series of carboxylic acids?methanoic acid HCO2Hethanoic acid CH3CO2H

propanoic acid C2H5CO2Hbutanoic acid C3H7CO2H

A CHO B CnH2nO C CnHnOn D CnH2nO2

25 What is the catalyst used in the preparation of ethyl ethanoate from ethanol and ethanoic acid?A concentrated sulphuric acid C nickelB vanadium(V) oxide D yeast

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

What is the structural formula of X?

A HCO2CH2CH2CH3 B CH3CO2CH2CH3 C CH3CH2CO2CH3 D CH3CH2CH2CO2H

27 The results of tests on compound Z are shown.test resultadd bromine wateradd aqueous sodium carbonate

turns colourlesscarbon dioxide formed

What is compound Z?

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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.carboxylic acid formulamethanoic acidethanoic acidpropanoic acid

HCOOHCH3COOHC2H5COOH

(a) Name the unbranched carboxylic acid that has four carbon atoms per molecule. (b) Give the formula of the sixth member of the carboxylic acid homologous series. (c) Ethanol, C2H5OH, reacts with ethanoic acid to make ethyl ethanoate.Draw the structure of ethyl ethanoate. (d) Name a reagent that can be used to convert ethanol into ethanoic acid. (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. (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 (g) Aqueous sodium hydroxide neutralises dilute ethanoic acid.Write the ionic equation for this reaction.

2 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. (ii) Draw the structure of the carboxylic acid used in the reaction. (iii) Write an equation for this reaction. (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. (ii) Name a solid substance that will react with both acids. Describe what you will seeduring the reaction. Substance………….. observations

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

Deduce the general formula for acid chlorides. (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.

alkanes acid chloridesformula name formula

C2H6 ethanoyl chloride CH3COClC3H8 C2H5COClC4H10 butanoyl chloride C3H7COClC5H12 pentanoyl chloride C4H9COCl

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

name acid formula relative molecular mass

melting point/C0 boiling point/C0

methanoic acid HCOOH 46 8.4 101ethanoic acid CH3COOH 60 17 118

propanoic acid C2H5COOH 74 -22 141butanoic acid C3H7COOH 88 -8 164

pentanoic acid(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 melting point. (b) Draw the displayed formula for propanoic acid. (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. (d) Ethanoic acid reacts with magnesium oxide.Name the products formed and write a balanced equation for the reaction. (e) Describe how ethanoic acid can be converted into ethyl ethanoate.

5 A student used the apparatus shown to produce ethanoic acid, CH3COOH.

A small volume of an alcohol was placed in the flask together with an oxidising agent. Themixture was warmed and a colour change was seen in the flask.(a) (i) Name and give the formula of the alcohol.name .......................................................................................................................formula ....................................................................................................................(ii) Suggest a suitable oxidising agent..................................................................................................................................(iii) What colour change was seen using the oxidising agent stated in (a) (ii)?...............................................................................................................................(b) Name the piece of apparatus marked B on the diagram. What is its purpose?name ..............................................................................................................................purpose .................................................................................................................................................................................................................................................................. (c) Suggest two items which the student should wear to ensure personal safety, whencarrying out the experiment.1. .................................................................................................................................2. ...............................................................................................................................

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Half of the alcohol was transferred to a flask and some acidified potassium dichromate(VI) wasadded. The mixture was warmed.(d) (i) What was the colour change during the reaction?from .................................... to ....................................(ii) What was the organic product of this reaction?..................................................................................... The compound from (d)(ii) was separated from the reaction mixture. It was addedto the other half of the alcohol from (c). A few drops of concentrated sulphuric acidwere added and the mixture was warmed.(e) (i) Name and give the formula of the organic compound formed.name ................................................................formula .............................................................(ii) To which group of organic compounds does this product belong?..........................................................................Half of the alcohol was transferred to a flask and some acidified potassium dichromate(VI) wasadded. The mixture was warmed.

6 The structures of three organic molecules are shown below.

(a) Describe an industrial process to make ethanol from ethene. (b) Name a reagent that can be used to convert ethanol into ethanoic acid. (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? (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? [

7 A student made a sample of the ester methyl propanoate, C2H5COOCH3.Which two compounds were heated together?A ethanoic acid and methanol B ethanoic acid and ethanolC propanoic acid and methanol D propanoic acid and ethanol

8 When aqueous ethanoic acid was added to ethanol, a sweet smelling liquid was produced.What type of reaction occurred?A esterification B hydrolysis C oxidation D reduction

9 An ester has the structural formula shown below.It can be prepared by the reaction between:

A methanol and methanoic acid. B methanol and ethanoic acid.C ethanol and methanoic acid. D ethanol and ethanoic acid.

10 A student made an ester by reacting an alcohol with an acid. Which one of the followingproduced an ester containing four carbon atoms?A methanol and ethanoic acidB ethanol and propanoic acidC propanol and methanoic acidD methanol and methanoic acid

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11 A student was given some ethanol. They added half of it to some acidified sodiumdichromate(VI) and warmed the mixture.The organic product X was separated and then reacted under suitable conditions with the other half of the ethanol.A product Y was formed.What are X and Y? X YA CH3CH2CH2OH CH3CH2CO2HB CH3CO2H C2H5CO2CH3

C CH3CO2H CH3CO2C2H5

D CH3OH CH3CO2H

12 Which of the following pairs of substances produces the compound shown below?

A ethene and ethanoic acid C methanol and ethanoic acidBethene and propanoic acid D ethanol and propanoic acid

13A student did some tests on ethanoic acid. Which result was incorrect?test result

A add sodium carbonate effervescenceB litmus paper turned redC warm with ethanol together

with two drops of concentrated sulphuric acida sweet smelling liquid

D warm with acidifiedpotassium dichromate(VI)

solution turns green

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

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

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

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

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

compound …………………………and compound ……………………………………………………….

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

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

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

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

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

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fraction from petroleum?

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

(f) Compound D burns readily.

(i) Burning is an exothermic reaction.

Explain the meaning of the term exothermic.

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

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

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

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

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

(g) Write down the molecular formula of compound C.

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

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

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

(i) Many fruits contain a variety of different coloured compounds.

What separation technique can you use to separate these different coloured

compounds?

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

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.

(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 an equation 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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