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combined chemistry > acids > Flashcards

acids Flashcards

topic 3 - chemical change

1
Q

what are acids in solution sources of

A

hydrogen ions

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2
Q

what are alkalis in solution sources of

A

hydroxide ions

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3
Q

recall the pH of acidic, alkaline and neutral solutions

A
  • acidic = lower pH value
  • neutral = 7
  • alkaline = higher pH value
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4
Q

what is the effect of acid and alkalis on the indicator litmus

A
  • red in acidic
  • purple in nuetral
  • blue in alkaline
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5
Q

what is the effect of acid and alkalis on the indicator methyl orange

A
  • red in acidic
  • yellow in neutral
  • yellow in alkaline
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6
Q

what is the effect of acid and alkalis on the indicator phenolphthalein

A
  • colourless in acidic
  • colourless in neutral
  • pink in alkaline
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7
Q

the higher the concentration of hydrogen ions in an acidic solution causes a high or low pH?

A

low pH

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8
Q

the higher the concentration of hydroxide ions in an alkaline solution causes the pH to be higher or low

A

higher

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9
Q

what happens to the pH of the solution when hydrogen ion concentration in the solution increases by a factor of 10

A

the pH of the solution decreases by 1

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10
Q

Core Practical: Investigate the change in pH on adding
powdered calcium hydroxide or calcium oxide to a fixed volume
of dilute hydrochloric acid - METHOD

A

method
- add dilute HCl to beaker and measure pH
- add weighed mass of calcium hydroxide and stir, recording the pH
- keep adding weighed masses of calcium hydroxide until there is no more change to the pH

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11
Q

Core Practical: Investigate the change in pH on adding
powdered calcium hydroxide or calcium oxide to a fixed volume
of dilute hydrochloric acid - ANALYSIS

A

analysis
- draw a line graph
-> mass on horizontal axis
-> pH on vertical axis
- line of best fit

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12
Q

Explain the terms dilute and concentrated, with respect
to amount of substances in solution

A
  • concentrated = larger amount of substance in given volume of solution
  • dilute = lesser amount of substance in a given volume of a solution
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13
Q

Explain the terms weak and strong acids, with respect to
the degree of dissociation into ions

A
  • strong acid = fully dissociated in aqueous solution
  • weak acid = partially dissociates in aqueous solution
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14
Q

dissociation means

A

where an acid breaks down to release H+ ions in solution

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15
Q

how does the strength of and acid affect its dissociation

A
  • stronger acid means greater dissociation
  • more H+ ions released
  • the lower pH (for a given concentration of aqueous solutions
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16
Q

what is a base

A

a substance that reacts with an acid to form a slat and water only

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17
Q

is an acid or an alkali a soluble base

A

alkali

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18
Q

the general reactions of aqueous solutions of acids with: METALS (to produce salts)

A

acid + metal -> salt + hydrogen gas

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19
Q

the general reactions of aqueous solutions of acids with: METAL HYDROXIDES (to produce salts)

A

acid + metal hydroxide -> salt + water

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20
Q

the general reactions of aqueous solutions of acids with: METAL OXIDES (to produce salts)

A

acid + metal oxide -> salt + water

21
Q

the general reactions of aqueous solutions of acids with: METAL CARBONATES (to produce salts)

A

acid + metal carbonate -> salt + water + carbon dioxide

22
Q

explain the general reactions of aqueous solution of acids with metal… to produce salts. - what do metal oxides and hydroxides act as

A
  • metal oxides are bases (because insoluble)
  • metal hydroxides are bases/alkalis if insoluble/soluble
23
Q

explian the general reactions of aqueous solution with acids with metals… how to name salts

A
  • first part is name of metal in oxide/hydroxide/carbonate
  • second part comes from the acid
    -> hydrochloric acid = chloride
    -> nitric acid = nitrate
    -> sulfuric acid = sulfur
24
Q

acid + base =
(Explain​ ​ the​ ​ general​ ​ reactions​ ​ of​ ​ aqueous​ ​ solutions​ ​ of​ ​ acids​ ​ with:
metals,​ ​ metal​ ​ oxides,​ ​ metal​ ​ hydroxides,​ ​ and​ ​ metal​ ​ carbonates​ ​ (all)​ ​ to
produce​ ​ salts)

A

salt + water

25
how to test for hydrogen
- LIT splint - goes out with squeaky pop
26
how to test for carbon dioxide
- limewater - turns cloudy
27
describe a neutralisation reaction
a reaction between an acid and a base
28
​Explain​ ​ an​ ​ acid-alkali​ ​ neutralisation​ ​ as​ ​ a​ ​ reaction​ ​ in​ ​ which​ ​ hydrogen ions​ ​ (H​ +​)​ ​ from​ ​ the​ ​ acid​ ​ react​ ​ with​ ​ hydroxide​ ​ ions (OH​-​)​ ​ from​ ​ the​ ​ alkali​ ​ to​ ​ form​ ​ water
- all neutralisation reactions with an acid and an alkali has an ionic equation of H+ (aq) + OH- (aq) -> H2O (l)
29
what is an acid-alkali neutralisation
- a reaction where hydrogen ions (H+) from the acid - react with hydroxide ions (OH-) from the alkali - to form water
30
explain why if soluble salts are prepared from an acid and an insoluble reactant an excess of the reactant is added
- to ensure your volume of acid reacts completely
31
explain why if soluble salts are prepared from an acid and an insoluble reactant the excess of reactant is removed
- done by filtration of the insoluble reactant - is done so that you are left with just salt and water
32
explain why if soluble salts are prepared from an acid and an insoluble reactant the solution remaining is only salt and water
- because all your acid hass fully reacted anf you have filtered off your other reactant -> the only products of your reaction are a salt and water
33
explain why if soluble salts are prepared from an acid and an insoluble reactant the solution remaining is only salt and water IF YOU USE CARBONATE
- still only have a salt and water remaining - as carbon dioxide gas would have been given off into atmosphere
34
explain why if soluble salts are prepared from an acid an a soluble reactant titration must be used
- both reactant are liquids/soluble so if you have an excess of one you wouldn't be able to easily remove it from you mixture of products -> so you need to measure the exact amount of volumes that react with is done easily using titration - can then mix exact proportions of the two reactants
35
what is titration
a technique where a solution of known concentration is used to determine the concentration of an unknown solution
36
​ ​ Explain​ ​ why,​ ​ if​ ​ soluble​ ​ salts​ ​ are​ ​ prepared​ ​ from​ ​ an​ ​ acid​ ​ and​ ​ a​ ​ soluble reactant the acid and the soluble reactant are then mixed in the correct proportions
- using titration you can measure the exact amount of volumes that react - to then mix the exact proportions of the two reactants
37
​ ​ Explain​ ​ why,​ ​ if​ ​ soluble​ ​ salts​ ​ are​ ​ prepared​ ​ from​ ​ an​ ​ acid​ ​ and​ ​ a​ ​ soluble reactant where the solution remaining after the reaction is only salt and water
- it is only salt and water because the exact amount of acid has been added to the soluble reactant -> so there is no acid or alkali as they have been completely neutralised
38
Core Practical: Investigate the preparation of pure, dry hydrated copper sulfate crystals starting from copper oxide including the use of a water bath
method - ADD AN EXCESS OF COPPER OXIDE (insoluble) to your acid (sulfuric acid as you are making copper SULFATE) - use a FILTER and filter paper to filter off any copper oxide that hasn't reacted (your solution should be blue as copper sulfate solution has been formed) - EVAPORATE OFF THE WATER by placing your final solution in a water bath
39
describe how to carry out an acid-alkali titration using burette, pipette and a suitable indicator to prepare a pure, dry salt
1. wash burette using acid then water 2. fill burette to 100cm cubed with acid with the meniscus' base on the 100cmcubed line 3. use 25 cm cubed pipette to add 25cm cubed of alkali into a conical flask 4. add few drops of a suitable indicator to the conical flask 5. add acid from burette to alkali until end-point is reached 6. the titre is the difference between the first and second readings on the burette 7. repeat 8. prepare pure, dry salt (warm salt solution to evaporate the water) 9. crystals form
40
what is a titre
the volume of alkali needed to exactly neutralise the acid
41
Recall the general rules which describe the solubility of common types of substances in water (soluble/insoluble) - common slats of sodium, potassium and ammonium
soluble
42
Recall the general rules which describe the solubility of common types of substances in water (soluble/insoluble) - all nitrates
soluble
43
Recall the general rules which describe the solubility of common types of substances in water (soluble/insoluble) - common chlorides
- common chlorides are soluble - except those of silver and lead
44
Recall the general rules which describe the solubility of common types of substances in water (soluble/insoluble) - common sulfates
- common sulfates are soluble - except those of lead barium and calcium
45
Recall the general rules which describe the solubility of common types of substances in water (soluble/insoluble) - common carbonates and hydroxides
- common carbonates and hydroxides are soluble - except those of sodium, potassium and ammonium
46
​Predict,​ ​ using​ ​ solubility​ ​ rules,​ ​ whether​ ​ or​ ​ not​ ​ a​ ​ precipitate​ ​ will​ ​ be formed​ ​ when​ ​ named​ ​ solutions​ ​ are​ ​ mixed​ ​ together,​ ​ naming​ ​ the​ ​ precipitate​ ​ if any
1. work out products of reaction 2. then use the general rules of solubility to determine if any salts formed are soluble or insoluble 3. INSOLUBLE salts will be formed as a precipitate (as any soluble salts will remain in solution)
47
- soluble meaning - insoluble meaning
- soluble: can be dissolved in water - insoluble: cannot be dissolved in water
48
- precipitate meaning
cause of a solid substance to be deposited in solid form from a solution
49
describe a method used to prepare a pure, dry sample of an insoluble salt
1. mix two solutions needed to form the salt 2. filter mixture using filter paper (which the insoluble salt will be left on) 3. wash salt using distilled water 4. leave salt to dry on filter paper (water will evaporate, speed this process up by drying it in an oven)

combined chemistry (13 decks)

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