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Chemistry > B15 Alcohols, alkanoic acids and esters > Flashcards

B15 Alcohols, alkanoic acids and esters Flashcards

1
Q

What is the functional group for an alcohol?

A

hydroxyl group, -OH

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2
Q

True or False: alcohols are named by using the prefix which indicates the total number of carbon atoms in the molecule plus the ending ‘-anol’.

A

true

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3
Q

Name the alcohol that has five carbon atoms.

A

pentanol

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4
Q

What is the general formula of an alcohol?

A

CnH2n+1OH

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5
Q

True or false: alcohol molecules are not polar

A

false. Alcohol molecules are polar due to the presence of the polar -OH group.

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6
Q

Alcohols are less volatile than their corresponding alkanes because ___________.

A

Because of the polar nature of the molecules. It causes the forces of attraction between the alcohol molecules to be stronger than between the non-polar alkane molecules.

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7
Q

Which of the following statements is true?
A. Polar solvents dissolve in polar solutes.
B. Non-polar solutes dissolve in polar solvents.
C. Polar solutes dissolve in polar solvents.

A

C. Polar solutes dissolve in polar solvents.

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8
Q

What products are formed during combustion of ethanol?

A

carbon dioxide and water

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9
Q

Write a chemical equation which summarises the complete combustion of ethanol.

A

C2H5OH (l) + 3O2 (g) ——> 2CO2 (g) + 3H2O (g)

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10
Q

True or False: Ethanol burns with a clear blue flame

A

True, because the ratio of carbon to hydrogen atoms in the molecule is low. All the carbon is converted to carbon dioxide- none remains to produce soot.

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11
Q

Complete the chemical equation:

2C2H5OH (l) + 2Na (s) —–> ?

A

2C2H5OH (l) + 2Na (s) —–> 2C2H5ONa (alc sol) + H2 (g)

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12
Q

What conditions are necessary for the dehydration of ethanol?
A. Heat and concentrated H2SO4
B. 5 atm pressure and 200 degrees Celcius
C. Heat
D. Concentrated H2SO4 and 170 degrees Celcius

A

D. Concentrated H2SO4 and 170 degrees Celcius

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13
Q

What product is formed when the elements of water are removed from an alcohol?

A

The corresponding alkene e.g. ethanol - water —-> ethene

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14
Q

During the breathalyser test to detect the presence of ethanol on a driver’s breath, the ethanol:
A. oxidises the green Cr3+ ion to the orange Cr2O7 ion
B. reduces the orange Cr2O7 ion to the green Cr3+ ion
C. reduces the green Cr3+ ion to the orange Cr2O7 ion
D. oxidises the orange Cr2O7 ion to the green Cr3+ ion

A

B. reduces the orange Cr2O7 ion to the green Cr3+ ion

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15
Q

True or False: Ethanol is oxidised to ethane when heated with acidified potassium manganate (VII) or acidified potassium dichromate (VI).

A

False: Ethanol is oxidised to ethanoic acid when heated with acidified potassium manganate (VII) or acidified potassium dichromate (VI).

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16
Q

Describe fermentation.

A

It is the chemical reaction in which carbohydrates are converted into ethanol by yeast under anaerobic conditions. Wine and rum are made by fermentation.

17
Q

What is the general formula for alkanoic acids?

A

CnH2n+1COOH

18
Q

The functional group of alkanoic acids is the _____ group, _____.

A

The functional group of alkanoic acids is the carboxyl group, - COOH.

19
Q

True or False: Alkanoic acid molecules are polar.

A

True

20
Q

Alkanoic acids are less volatile than their corresponding alkanes, because _____.

A

Because the forces of attraction between the polar alkanoic acid molecules are stronger than between the non-polar alkane molecules.

21
Q

metals + alkanoic acid —–> ?

A

metals + alkanoic acid —-> salt + hydrogen

22
Q

metal oxide + alkanoic acid —–> ?

A

metal oxide + alkanoic acid —–> salt + water

23
Q

alkali + alkanoic acid —–> ?

A

alkali + alkanoic acid —-> salt + water

24
Q

carbonates + alkanoic acid ——> ?

A

carbonates + alkanoic acid —-> salt + water+ carbon dioxide

25
Q

sodium bicarbonate + alkanoic acid —-> ?

A

sodium bicarbonate + alkanoic acid —-> salt + water + carbon dioxide

26
Q

Define esterification.

A

This is the process in which a carboxylic acid reacts with an alcohol to produce an ester and water.

27
Q

What are the conditions necessary for esterification?

A

concentrated H2SO4 (catalyst, dehydrating agent) and heat

28
Q

What is the general formula for esters?

A

CnH2n+1COOCxH2x+1

29
Q

The functional group for esters is _______.

A

-COO-

30
Q

True or False: Sugars and salts are esters.

A

False. Fats and oils are esters.

31
Q

Summarise esterification using a word equation.

A

alkanoic acid + alcohol –conc. H2SO4 and heat—-> ester + water

32
Q

butanol + propanoic acid —> ?

A

butanol + propanoic acid —-> butyl propanoate + water

33
Q

Briefly describe acid hydrolysis of esters.

A

The ester is heated with an acid catalyst such as dilute hydrochloric or sulfuric acid.

34
Q

Does this equation accurately summarise acid hydrolysis of ethyl ethanoate?

CH3COOC2H5 (l) + H20 (l) –conc. H2SO4, heat—-> CH3COOH (l) + C2H5OH (l)

A

Yes.

35
Q

True or False: During alkaline hydrolysis, the ester is heated with sodium and potassium carbonate.

A

False. During alkaline hydrolysis, the ester is heated with sodium and potassium hydroxide solution.

36
Q

Which of the following are true for saponification?

I. it is the alkaline hydrolysis of large esters
II. it produces water and a salt
III. it is used in the manufacture of soap

A. I only
B. I and III only
C. II only
D. I, II and III

A

B. I and III only

37
Q

The ionic head is the ________ end of a detergent molecule and the tail is the ____________ end.

A

The ionic head is the hydrophilic end of a detergent molecule and the tail is the hydrophobic end.

38
Q

State two ways in which a soap prepared from a fat or oil differs from a soapless detergent.

A

Soapy detergents do not lather easily in hard water, while soapless detergents lather in hard water. Soapy detergents are biodegradable, while soapless detergents are non-biodegradable.

Chemistry (3 decks)

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