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Chemistry: Paper 1 > Chemical Changes > Flashcards

Chemical Changes Flashcards

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1
Q

What do acids produce in aqueous solution

A

H+ ions

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2
Q

What do alkaline produce in aqueous solution

A

OH- ions

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3
Q

What is the pH of a neutral solution

A

7

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4
Q

What is the pH of an alkaline solution

A

more than 7 (stops before 14)

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5
Q

What is the pH of a acidic solution

A

less than six (stops at 0)

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6
Q

What does acids and alkaline do to phenolphthalein indicator

A

Acids = colourless
Alkaline = Pink

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7
Q

What does acids and alkaline do to methyl orange indicator

A

Acidic = red
Alkaline = yellow

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8
Q

What does acids and alkaline do to litmus solution

A

Acidic = red
Alkaline = blue

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9
Q

What colour does blue litmus paper go in acids and alkaline

A

Acid = turns red
Alkaline = stays blue

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10
Q

What colour does red litmus paper go in acids and alkaline

A

Acid = stays red
Alkaline = turns blue

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11
Q

What do acids with a lower pH have

A

A higher concentration of H+ ions

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12
Q

What do alkaline with a higher pH have

A

A higher concentration of OH- ions

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13
Q

What does a pH of 1 represent

A

Hydrogen ion concentration of 0.1mol/dm^3

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14
Q

What happens as you increase the pH by 1

A

you decrease the H+ ion concentration by 10

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15
Q

Derive a test to measure the change in pH

A
  1. Add dilute HCL into beaker and measure the pH
  2. Add a weighed mass of Calcium hydroxide and stir
  3. Record new pH
  4. Repeat and measure the change of acidity
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16
Q

Define a strong acid

A

fully dissociates in aqueous solution

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17
Q

Define a weak acid

A

partially dissociates in aqueous solution

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18
Q

State the neutralisation equation

A

acid + base -> salt + water
HCL + NaOH -> NaCl + H20

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19
Q

what is the general equation for a metal

A

acid + metal → salt + hydrogen gas (H2)

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20
Q

what is the general equation for a metal oxide

A

acid + metal oxide → salt + water

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21
Q

what is the general equation for a metal hydroxide

A

acid + metal hydroxide → salt + water

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22
Q

what is the general equation for a metal carbonate

A

acid + metal carbonate → salt + water + carbon dioxide (CO2)

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23
Q

What is the test for hydrogen

A

Place burning splint held at the open end of a test tube of the gas - should create a ‘squeaky pop’ sound

24
Q

What is the test for carbon dioxide

A

Bubble the gas through limewater
Will turn milky/ cloudy

25
Q

What is the ionic equation for neutralisation

A

H+ (aq) + OH- (aq) = H2O (l)

26
Q

How is a soluble salt made

A

Mixing of a acid and insoluble base

27
Q

Why is the insoluble reactant added in excess when preparing a soluble salt

A

To ensure all the acid has reacted

28
Q

How is excess reactant removed from a soluble salt

A

filtration - leaves behind salt and water

29
Q

Why is titration used when make soluble salts with an acid and soluble reactant (3 points)

A

1-solutions are soluble excess cannot easily be removed
2- Titrations provide exact proportions
3- Everything will neutralsises except salt and water

30
Q

Core practical: derive a method to prepare copper sulphate crystals (3 steps)

A

1- add an excess of copper oxide to sulphuric acid
2- filter off any copper oxide that hasn’t reacted
3- evaporate off the water by placing final solution in a water bath

31
Q

Describe how to carry out an acid-alkali titration resulting in crystals to form (6 steps)

A
  1. Wash burette using the acid and then water
  2. Fill burette to 100cm3 with acid
  3. Use a pipette to add 25cm3 of alkali into a conical flask
  4. Add a few drops of a suitable indicator to the conical flask
  5. Add acid from burette to alkali until end-point is reached
    6- warm the salt solution to evaporate the water
32
Q

What are concordant titres

A

Titres within 0.10 cm^3 of each other

33
Q

What solutions are ALWAYS soluble (6 groups)

A

N- Nitrates
A- Acetates
G- Group 1

S- Sulfates
A- Ammonium
G- Group 17

34
Q

Which group 17 elements are not soluble (name 3)

A
  1. Lead
  2. Mercury
  3. Silver
35
Q

Which sulphates are not soluble (name 3)

A

1- Calcium
2- Strontium
3- Barium

36
Q

What are the ONLY soluble carbonates/hydroxides (name 3)

A

1- sodium
2- potassium
3- ammonium

37
Q

What do insoluble salts form as

A

Precipitate

38
Q

Describe how you produce a pure, dry sample of a soluble salt

A
  1. mix the two solutions needed to form the salt
  2. filter the mixture using filter paper, which the insoluble salt will be left on
  3. place on a water bath, and heat until about half the water from the solution has been removed by evaporation.
  4. leave for small cystals to start forming around the edge of the evaporating basin.
39
Q

What are electrolytes

A

Ionic compounds that are dissolved or in molten state so that ions are free to move

40
Q

What is electrolysis

A

The use of electricity to break down electrolytes to form elements

41
Q

Describe the movement of ions in electrolysis

A

Cations move towards the Cathode
Anions move towards the Anode

42
Q

What is the name of the positive electrode where oxidation occurs

A

Anode

43
Q

What is the name of the negative electrode where reduction occurs

A

Cathode

44
Q

What ions are in aqueous solutions when separated

A

Ions that make up the ionic compound
Ions that found in water ( H+ and OH- )

45
Q

What is the rule for the discharge of ions at the cathode in aqueous solutions

A

The ion of the least reactive element will be discharged

46
Q

What is the rule for the discharge of ions at the anode in aqueous solutions

A

OH- ions are always discharged unless a halide is present

47
Q

What happens at the electrolysis of Copper chloride

A
  • Cu+ go to the cathode 🡲 Cu (s) produced
  • Cl- ions go to the anode 🡲 Cl2 (g) produced
48
Q

What happens at the electrolysis of sodium chloride

A

H+ ions go to cathode 🡲 H2 (g) produced
Cl- ions go to anode 🡲 Cl2 (g) produced

49
Q

What happens at the electrolysis of sodium sulphate

A

H+ ions go to cathode 🡲 H2 (g) produced
OH- ions go to anode 🡲O2 (g) produced

50
Q

What happens at the electrolysis of water acidified with sulfuric acid

A

H+ to cathode 🡲 H2 (g) is produced
OH- to anode 🡲 O2 (g) is produced

51
Q

What happens at the electrolysis of molten lead bromide

A

Pb2+ to cathode 🡲 Pb (s) produced
Br- to anode 🡲 Br2 (l) produced

52
Q

What is oxidation and reduction in terms of electrons

A

Oxidation
Is
Loss
Reduction
Is
Gain

53
Q

How is electrolysis used to purify copper

A

Anode is impure copper
Cathode is pure copper
Solution is copper sulfate
Cu2+ ions from anode more to cathode 🡲 gain electrons 🡲 discharged as pure copper
Impurities form as sludge below the anode

54
Q

Investigate the electrolysis of copper sulphate with inert electrodes

A

Cu (s) produced at cathode
O2 (g) produced at anode
H+ and SO4^2- ions left in solution react to form sulfuric acid

55
Q

What is the ionic half equation for reactions at the negative electrode (reduction)

A

Gains an elecron so: (X+) + e- 🡲 X

56
Q

What is the ionic half equation for reactions at the positive electrode (oxidation)

A

(X-) 🡲 (e-) + X

Chemistry: Paper 1 (5 decks)

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