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IGCSE Chemistry > C8 - Acids, bases and salts (Only C8.1 - C8.3) > Flashcards

C8 - Acids, bases and salts (Only C8.1 - C8.3) Flashcards

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1
Q

When any substance is dissolved in water it forms an

A

aqueous solution

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2
Q

Aqueous solutions can be either

A

acidic, alkaline or neutral

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3
Q

What does an indicator do

A

tells if a solution is acidic, alkaline, or neutral by changing color

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4
Q

Acids are substances that form

A

Hydrogen (H+) ions when dissolved in water

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5
Q

A base is any substance that can

A

neutralize an acid

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6
Q

Acids are proton

A

donors

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7
Q

Bases are proton

A

acceptors

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8
Q

Bases can either be

A

soluble or insoluble in water

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9
Q

Bases that are soluble in water are called

A

alkalis

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10
Q

Alkalis are substances that release

A

hydroxide (OH-) ions in aqueous solutions which are typically metal hydroxides

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11
Q

Two main types of insoluble bases are

A

metal carbonates and metal oxides

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12
Q

All acids ionize (become ions) in aqueous solutions and the strength of the acid is determined by

A

how much it ionizes water

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13
Q

Characteristics and examples of weak acids

A

Only partially ionize in water meaning not all acid molecules break up (dissociate) to form H+ ions
Most acids are weak acids
Example: ethanoic acid CH3COOH <==> CH3COO- + H+
Citric acid
Carbonic acid

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14
Q

Characteristics and examples of strong acids

A

They fully ionize in water meaning all the acid molecules break up (dissociate) to form H+ ions
Example: HCI ==> H+ + Cl-
HNO3 ==> H+ + NO3-
Other strong acids include: sulfuric and nitric acid

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15
Q

When bases neutralize acids they form

A

salt and water

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16
Q

Characteristics and examples of weak bases

A

Weak bases don’t fully ionize in aqueous solutions as only a few of the molecules break up (dissociate) to form OH- ions
Example: Ammonia NH3
NH3 + H2O ==> NH4+ + OH-

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17
Q

Characteristics and examples of strong bases

A

Strong bases full ionize in aqueous solutions meaning all the molecules break up (dissociate) to form OH- ions
Examples of strong bases include:
Potassium hydroxide: KOH ==> K+ + OH-
Sodium hydroxide: NaOH ==> Na+ + OH-

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18
Q

When acids react with metals what is produced

A

a hydrogen and a salt

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19
Q

Examples of acids + metals

A

Zinc + sulfuric acid ==> zinc sulfate + hydrogen

Magnesium + hydrochloric acid ==> magnesium chloride + hydrogen

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20
Q

What is a neutralization reaction

A

when an acid and a base react to form a salt and water

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21
Q

Metal carbonate, metal oxides and metal hydroxides are all

A

bases

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22
Q

When an acid reacts with metal hydroxides it forms

A

salt + water

i.e hydrochloric acid + sodium hydroxide ==> sodium chloride + water

23
Q

When an acid reacts with a metal oxide it forms

A

salt + water

i.e hydrochloric acid + magnesium oxide ==> magnesium chloride + water

24
Q

When bases are heated with ammonium salts it gives off

A

ammonium gas

25
Q

Base + ammonium salt ==>

A

salt + ammonia (gas) + water

26
Q

How can we control soil acidity so that plants can grow properly?

A

add a suitable base such as slaked lime to soil to neutralize soil acidity to create an optimum pH for the plant to grow in

27
Q

How to determine whether a substance is an acid or alkali

A

finding out the pH or using an indicator

28
Q

What does pH relate to

A

the concentration of H+ ions

29
Q

Difference between strength and concentration

A

Strength of an acid relates to how much an acid can dissociate as concentration relates to how much acid there is in a certain volume
i.e you can have high concentration HCI as well as low concentration HCI (dilute)

30
Q

The more H+ ions a substance has

A

the lower the pH gets

31
Q

Examples of indicators and what color it turns

A 
Methyl orange: 
Red in acid
Yellow in neutral and alkali
Litmus paper:
Red in acid
Violet in neutral
Blue in alkali
Phenolphthalein:
Colorless in acid
Pink in alkali
32
Q

Oxides of elements can be made by

A

heating the element in air or oxygen

33
Q

Basic oxides characteristics and examples

A

Metals form metal oxides which are basic oxides
These oxides dissolve in water to form OH- ions
i.e Magnesium
2Mg + O2 ==> 2MgO

34
Q

Amphoteric oxides characteristics and examples

A

They are oxides of less reactive metals like Al2O3, ZnO and PbO
They react with both acids and alkalis to produce salts

35
Q

Acidic oxides characteristics and examples

A

Non metals form non metal oxides which are acidic
i.e Sulfur dioxide
Oxides are normally gases and dissolve in water to form mineral acid and release H+ ions

36
Q

Neutral oxides characteristics and examples

A

They don’t react with acids or alkalis

i.e Carbon monoxide and water

37
Q

How to test for insoluble oxides

A

If they react with HCI they are basic oxides
If they react with NaOH they are acidic oxides
If they react with none of the above they are neutral oxides

38
Q

Acid(aq) + alkali(aq) ==>

A

salt(aq) + water(l)

39
Q

Acid(aq) + base(s) ==>

A

salt(aq) + water(l)

40
Q

Acid(aq) + carbonate(s) ==>

A

salt(aq) + water(l) + carbon dioxide(g)

41
Q

Acid(aq) + metal(s) ==>

A

salt(aq) + hydrogen(g)

42
Q

What are the solubility rules

A

All common sodium, potassium and ammonium salts are soluble
All nitrates are soluble
Chlorides, bromides and iodides are soluble - except silver chloride, silver bromide and silver iodide
Sulfates are soluble - except barium, lead and calcium
Carbonates are insoluble - except sodium, potassium and ammonium

43
Q

What experimental techniques are used to produce a pure dry sample of soluble salt from a soluble base, carbonate or metal.

A

Apparatus: heatproof mat, tripod, bunsen burner, acid, insoluble solid, stirring rod, paper filter, funnel, beaker, evaporating basin and petri dish

Preparation: Gently warm an acid using a bunsen burner
add insoluble solid (stirring) until it no longer reacts
Filtration: Filter the solution to remove the excess insoluble solid
(This will leave a solution of salt dissolved in water)
Crystallization: Heat the solution in an evaporating basin
After heated pour the solution into a petri dish
Leave the solution to cool and allow more water to evaporate
The salt will begin to crystallize and form

44
Q

If two solutions of soluble salts are mixed together what are the two salts it produces

A

a soluble and an insoluble salt.

45
Q

What does the insoluble salt produce in a reaction between two soluble salts

A

A precipitate - a solid made in the solution

This process is called precipitation

46
Q

What is an example of the process of precipitation

A

Na2CO3 (aq) + CuSO4 (aq) ==> CuSO3 (s) + Na2SO4 (aq)

insoluble salt is shown as an (s)

47
Q

if a substance is aqueous it is

A

soluble in water

48
Q

Steps and apparatus for the practical of making a precipitate of an insoluble salt

A

Apparatus: measuring cylinder, 2 test tubes, filter paper, stirring rod, funnel and beaker

Steps: Add exact amounts of the 2 salt solutions together
After that an insoluble salt will form as a precipitate which is solid
Pour the test tube into a funnel where the insoluble salt will be collected as residue at the top.
Take out the lamp filter paper with the insoluble salt in it.
Wash the residue with a little cold water and leave it out to dry.

49
Q

What is the experiment method which involves an acid and an alkali

A

titration experiement

50
Q

What does a titration determine

A

the volumes of acid and alkali that must be mixed to obtain a solution of only salt and water

51
Q

Steps and apparatus for carrying out a titration between an acid and alkali

A

Apparatus: Pipette, burette, conical flask, safety pipette filter, white tile and clamp stand

Steps: Use the pipette and pipette filler to add a measured volume of sodium hydroxide solution to a clean conical flask.
Add a few drops of indicator and put the conical flask on a white tile.
Fill the burette with hydrochloric acid and note the starting volume.
Slowly add the acid from the burette to the alkali in the conical flask, swirling to mix.
Stop adding the acid when the end-point is reached (when the indicator first permanently changes colour). Note the final volume reading.
Repeat the steps again with a new batch to get more accurate results.

52
Q

Ions of metals are

A

cations

53
Q

Steps of flame test and what it produces

A

Steps: Dip a piece of nichrome wire into concentrated HCI solution,
Dip it into a solid compound
Put it over a blue bunsen flame
The color seen in the flame identifies the metal ion in the compound

Lithium = bright red
Sodium = Golden yellow/orange
Potassium = lilac
Copper = green

IGCSE Chemistry (16 decks)

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