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Chemistry MA > carboxylic acids > Flashcards

carboxylic acids Flashcards

1
Q

what is the functional group of carboxylic acid?

A

-COOH

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2
Q

draw out the functional group of carboxylic acids

A

-C-O-H
II
O

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3
Q

what is vinegar in relation to ethanoic acid?

A

vinegar is an aqueous solution containing ethanoic acid

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4
Q

how are carboxylic acids formed?

A

it is formed by the oxidation of the corresponding alcohols, e.g., ethanoic acid is formed when ethanol is left in the air or oxidised using potassium dichromate (VI) in dilute sulfuric acid

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5
Q

what is the molecular formula of methanoic acid?

A

CH2O2

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6
Q

what is the molecular formula of ethanoic acid?

A

C2H4O2

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7
Q

what is the molecular formula of propanoic acid?

A

C3H6O2

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8
Q

what is the molecular formula of butanoic acid?

A

C4H8O2

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9
Q

what is the structural formula of methanoic acid?

A

HCOOH

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10
Q

what is the structural formula of ethanoic acid?

A

CH3COOH

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11
Q

what is the structural formula of propanoic acid?

A

CH3CH2COOH

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12
Q

what is the structural formula of butanoic acid?

A

CH3CH2CH2COOH

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13
Q

draw out the displayed formula for methanoic acid, ethanoic acid, propanoic acid, butanoic

A

check in p.294

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14
Q

what type of acid is carboxylic acid?

A

they are weak acids?

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15
Q

what are weak acids?

A

acids with a pH of about 3-5 depending on conc. of solution.

A weak acid is an acid that only partially dissociates into ions in water, producing a relatively small number of hydrogen ions (Ht). Weak acids have a relatively low pH value.

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16
Q

how does ethanoic acid react with water?

A

it reacts the same way other dilute acids react but MORE SLOWLY.
metal + acid -> salt + hydrogen
metal hydroxide/oxide + acid -> salt + water
metal carbonate + acid -> salt + carbon dioxide

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17
Q

what happens when ethanoic acid reacts with magnesium?

A

lots of fizzing. salt and hydrogen formed. the salt is called magnesium ethanoate

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18
Q

what is the name of salts that contain ethanoic, methanoic etc., acids in them?

A

methanoate
ethanoate
propanoate
butanoate

19
Q

what is an ethanoate ion?

A

part of a salt containing athanoic acid
it looks like CH3COO-

20
Q

is an ethanoic acid is weak?

A

it only partially dissociates in solution

21
Q

what is the equation for ethanoic acid and sodium hydroxide? word

A

ethanoic acid + sodium hydroxide-> sodium ethanoate + water

22
Q

what is the equation for ethanoic acid and sodium hydroxide? symbol (structural)

A

2CH3COOH + NaOH -> 2CH3COO-Na+ + H2O

23
Q

what is the equation for ethanoic acid and magnesium ? word

A

magnesium + ethanoic acid -> water + magnesium ethanoate

24
Q

what is the equation for ethanoic acid and magnesium ? symbol

A

CH3COOH + Mg -> (CH3COO)2Mg + H2O

25
Q

how are carboxylic acids formed?

A

they are formed by the oxidation of their corresponding alcohols

e.g., ethanoic acid is formed when ethanol is left in the air or oxidise

26
Q

how do you oxidise ethanol?

A
  • a few drops of ethanol are added to a solution containing a solution containing the orange mixture of dilute sulphuric acid and potassium dichromate (VI).
  • the test tube is heated in a hot water bath.
  • the solution turns green and now contains a very dilute solution of ethanoic acid together with the other products
  • the green colour indicates the presence of Cr3+ ions, which are formed when potassium (VI) dichromate is reduced

(wear goggles in case reaction is vigorous and spits out)

27
Q

what is the word equation for the oxidation of ethanol?

A

ethanol + potassium dichromate (VI) in dilute sulphuric acid -> ethanoic acid + water

heat under reflux

28
Q

what is the oxidising agent in the oxidation of ethanol?

A

acidified potassium dichromate (VI) aka potassium dichromate (VI) in dilute sulphuric acid

29
Q

write out the symbol equation for the oxidation of ethanol
structural formula

A

CH3CH2OH + 2[O] -> CH3COOH + H2O

across the arrow: reflux and K2Cr2O7/H2SO4

30
Q

what conditions are required for oxidation?

A

you must heat under reflux, meaning you stop the vapour from escaping

31
Q

draw out, in displayed fromula, the oxidation of ethanol

32
Q

what is the oxidising agent in the oxidation of the oxidation of an alcohol?

A

acidified potassium dichromate (VI)

33
Q

what happens to the dichromate in the oxidation of an alcohol?

what colour change takes place?

A

Cr2O7 (charge:2-) -> Cr (charge:3+)
charge on Cr (oxidation no): 6+ -> 3+
colour changes from orange to green

34
Q

what happens in the reaction between magnesium and dilute ethanoic acid? what is the equation?

A

Mg (s) + 2CH2COOH (aq) -> (CH3COO)2MG (aq) + H2 (g)

lots of fizzing and a salt+ hydrogen produced

35
Q

state 2 observations for the oxidation of the alcohold in the presence of acidified potassium dichromate (VI) solution

A

colour change: orange to green
product smells acidic (like vinegar)

36
Q

how can you show that an alcohol has been oxidised and an acid has fromed?

A

universal indicator

37
Q

why does old alcohol have an acidic taste?

A

it is exposed to oxygen and it oxidises in the air due to bacteria/yeast and ethanoic acid is made

38
Q

what happens when a metal carbonate and a carboxylic acid reacts?

A

metal carbonate + acid -> co2+ h2o + salt (e.g., sodium ethanoate)

39
Q

what is the charge of ‘ethanoate’ ions. draw out the displayed and structural formula of an ethanoate ion

40
Q

how do different metals react with carboxylic acids?

A

they react more/less vigorously depending on their position on the reactivity scale e.g., sodium is dangerously reactive , whereas zinc produces bubbles of hydrogen more slowly than it does with HCl

41
Q

what can you observe when sodium carbonate or calcium carbonate reacts with an ethanoate?

A

lots of fizzing and a colourless solution containing the salt

42
Q

The colour of bromine water is orange.
State the final colour of the mixture after bromine water is shaken with:
an unsaturated fat
and a saturated fat

A

unsaturated - colourless
saturated - orange

43
Q

Which type of fat contains a double carbon to carbon (C C) bond?

A

unsaturated fats

Chemistry MA (18 decks)

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