Acids, alkalis and bases Flashcards

summer exam revision 2/5/24

1
Q

the pH scale goes from - to -

acids and alkalis

A

0 to 14

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2
Q

the strongest acid has pH ?

acids and alkalis

A

pH 0

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3
Q

the strongest alkali has pH ?

acids and alkalis

A

pH 14

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4
Q

a neutral substance has a pH ?

acids and alkalis

A

pH 7

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5
Q

example of a neutral substance

acids and alkalis

A

pure water

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6
Q

litmus paper changes colour at about pH -?

acids and alkalis

A

pH 7

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7
Q

litmus paper is - in acidic solutions

acids and alkalis

A

red

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8
Q

litmus paper is - in neutral solutions

acids and alkalis

A

purple

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9
Q

what colour is litmus paper in alkaline solutions?

acids and alkalis

A

blue

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10
Q

what colour is phenolphthalein in acidic solutions?

acids and alkalis

A

colourless

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11
Q

what colour is phenolphthalein in alkaline solutions?

acids and alkalis

A

bright pink

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12
Q

what colour is methyl orange in in acidic solutions?

acids and alkalis

A

red

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13
Q

what colour is methyl orange in alkaline conditions?

acids and alkalis

A

yellow

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14
Q

what can acids be neutralised by?

acids and alkalis

A

bases (or alkalis)

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15
Q

an acid is a source of - ions (-)

acids and alkalis

A

hydrogen ions (H+)

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16
Q

acids are proton -

acids and alkalis

A

they are proton donors

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17
Q

acids have a pH - than 7

acids and alkalis

A

less than 7

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18
Q

a - is a substance that can neutralise an acid

acids and alkalis

A

base

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19
Q

bases are proton -

acids and alkalis

A

they are proton acceptors

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20
Q

– are soluble bases

acids and alkalis

A

alkalis

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21
Q

alkalis are soluble -

acids and alkalis

A

bases

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22
Q

alkalis are - bases

acids and alkalis

A

soluble

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23
Q

an alkali is a source of - ions (-)

acids and alkalis

A

hydroxide ions (OH-)

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24
Q

alkalis have a pH - than 7

acids and alkalis

A

greater than 7

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25
what is the name of the reaction that happens between an acid and a base (or an acid and an alkali) ? | acids and alkalis
neutralisation
26
what ions are involved in a neutralisation reaction? | acids and alkalis
hydrogen ions, H+, and hydroxide ions, OH-
27
what is the ionic equation for a neutralisation reaction? | acids and alkalis
H+ (aq) + OH- (aq) --> H2O (l)
28
a neutralisatoion reaction can also be seen in terms of a proton --. the acid -- protons which are then -- by the base. | acids and alkalis
-- proton transfer -- donates -- accepted
29
when an acid neutralises a base (or vice versa), the products are --, i.e. they have a pH of -- | acids and alkalis
-- neutral -- 7
30
acid + base --> ?
salt + water
31
metal + acid -->
salt + hydrogen | (M+A-->S+H)
32
acid + metal hydroxide --> ?
salt + water
33
acid + ammonia --> ?
ammonium salt
34
acid + metal carbonate --> ?
salt + water + carbon dioxide
35
titrations allow you to find out exactly how much -- is needed to -- a quantity of alkali (or vice versa)
-- acid -- neutralise
36
equipment for a titration (4 things)
- pipette - conical flask - burette - white tile
37
what is a pipette used for in a titration?
to accurately measure a certain volume of acid or alkali (usually 25cm^3)
38
what is a conical flask used for in a titration?
to contain the liquid from the pipette
39
what is a burette used for in a titration?
used for adding alkali or acid to the conical flask
40
what is a white tile used for in a titration?
to put the conical flask on | (so that it's easier to spot the colour change)
41
describe how to carry out a titration | (adding acid to the alkali)
1. use a pipette to add 25cm^3 of alkali to a clean conical flask 2. add a few drops of phenolphthalein indicator and place conical flask on white tile - the solution will turn PINK 3. fill burette with acid and note the starting volume 4. slowly add the acid from the burette to the alkali in the conical flask, swirling to mix 5. stop adding the acid when the end-point is reached - this is when the acid has neutralised the alkali and the phenolphthalein indicator changes colour from PINK TO COLOURLESS 6. note final volume reading of acid and calculate how much was added in total 7. Repeat the titration until you get 'concordant results', which means volumes of acid that are within 0.10 cm^3 of each other 8. use the concordant results to calculate the mean volume of acid required to neutralise the alkali
42
what colour is litmus indicator in acidic solutions?
red
43
what colour is litmus indicator in alkaline solutions?
blue
44
what colour is phenolphthalein indicator in acidic solutions?
colourless
45
what colour is phenolphthalein in alkaline solutions?
pink
46
what colour is methyl orange in acidic solutions?
red
47
what colour is methyl orange in alkaline solutions?
yellow
48
what precaution should be taken during a titration to reduce the risk of harm from acid burns?
wearing gloves
49
why should you swirl the conical flask during the titration?
to evenly distribute the added acid/alkali
50
what is a salt?
a compound that contains a positive ion (cation) and a negative ion (anion) | e.g. NaCl contains a positive Na+ ion and a negative Cl- ion
51
Which piece of apparatus should you use to accurately measure the volume of your acid or alkali before transferring it to a conical flask?
pipette | (normally 25cm^3 of acid/alkali is measured with a pipette)
52
what is meant by a soluble salt?
a salt that dissolves in water
53
what is meant by an insoluble salt?
a salt that does not dissolve in water
54
soluble or insoluble: common salts of SODIUM, POTASSIUM and AMMONIUM?
soluble
55
soluble or insoluble: NITRATES?
soluble
56
soluble or insoluble: common CHLORIDES?
soluble (except SILVER chloride and LEAD chloride)
57
soluble or insoluble: common SULPHATES?
soluble (except LEAD, BARIUM and CALCIUM sulphate)
58
soluble or insoluble: common CARBONATES?
insoluble (except for SODIUM, POTASSIUM and AMMONIUM ones)
59
soluble or insoluble: common HYDROXIDES?
insoluble (except for SODIUM, POTASSIUM and CALCIUM ones)
60