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Chemistry > Chemical changes > Flashcards

Chemical changes Flashcards

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1
Q

What does the pH scale range from

A

0-14

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2
Q

Where are Acids and Alkalis on the pH scale

A

0-6.9 is acids
7 is neutral
7.1- 14 is alkalines

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3
Q

What can be used to measure the pH of a solution

A

An indicator like universal indicator that shows colours like the rainbow

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4
Q

What ions do acids and alkalines form

A

Acids- H+ ions
Alkaline- OH- ions

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5
Q

What is an acid

A

A substance that forms aqeous solution with a pH less than 7. Acids form H+ ions in water

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6
Q

What is a base

A

A substance with a pH over 7

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7
Q

What is an alkali

A

A substance that forms aqeous solution with a pH more than 7. Acids form OH- ions in water

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8
Q

What is the reaction between acids and bases called

A

Neutralisation

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9
Q

Give the generic formula of neutralisation reaction

A

Acid + Base –> Salt + Water

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10
Q

What is a strong acid and give an example

A

An acid that fully ionises an aqeous solution and all acid particles dissociate to release H+ ions
Example: HCl

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11
Q

What is a weak acid and give an example

A

An acid that only partially ionises in an aqeous solution and only a small proportion of acid particles dissociate to form H+ ions
Example: Ch3COOH- Ethanoic acid

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12
Q

Are strong or weak acids reversible

A

You can reverse weak acids dissociating by reacting it with other things.

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13
Q

What relates H+ ions and rate of reactions and how do strong and weak acids’ reactivities compare

A

If concentration of H+ ions is higher, the rate of reaction will be faster so strong acids will be more reactive than weak acids of the same concentration

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14
Q

How does concntration of hydrogen change as pH increases

A

It is a logarithmic scale, so the scale is 10^x when x is the pH change

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15
Q

What is the difference between a strong acid and a concentrated acid

A

Acid strength tells you what proportion of the acids is ionises
Acid concentrationis how much acid there is in a volume of water

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16
Q

What are metal oxides and metal hydroxides examples of

A

Bases

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17
Q

What will happen if you react an acid and metal oxide and give an example with HCl and CuO

A

Acid + Metal Oxide –> Salt + Water
Hydrochloric acid + Copper Oxide –> Copper chloride + Water
2HCl + CuO –> CuCl2 + H2O

18
Q

What will happen if you react an acid and metal oxide and give an example

A

Acid + Metal Oxide –> Salt + Water
Sulfuric acid + Potassium hydroxide –> Potassium sulfate + Water
H2SO4 + 2KOH –. K2SO4 + H2O

19
Q

What does an acid and metal carbonate produce and give an example

A

Acid + Metal carbonate –> Salt + Water + Carbon dioxide
HCl + Na2CO3 –> 2NaCl + H2O + CO2

20
Q

What is the reactivity series (elements)

A

Potassium
Sodium
Calcium
Magnisium
Aluminium
Carbon
Zinc
Iron
Tin
Lead
Hydrogen
Copper
Silver
Gold
Platinum

21
Q

Metal + Acid —->

A

Salt + Hydrogen

22
Q

What does a metal reacting with an acid tell you about reactivity

A

If it is a reactive metal, it will react vigotously and fast.
If it is a non reactive metal, it will react slowly with minimal efforvescence.

23
Q

Metal + Water —>

A

Metal hydroxide + Hydrogen

24
Q

What metals wont react with water

A

Non reactive ones like zinc iron copper and transition metals

25
Q

Oxidation

A

Loss of electrons

26
Q

Reduction

A

Gain of electrons

27
Q

How can carbon be used in extraction of metals from ores.

A

Carbon is more reactive than the metal e.g. iron so it displaces it from the compound:
Iron oxide + Carbon –> Iron + Carbon dioxide

28
Q

How are metals higher than carbon in the reactivity series extracted

A

Electrolysis

29
Q

What are redox reactions

A

When both reduction and oxidation occurs

30
Q

What is a displacement reaction

A

When a more reactive metal will displace a less reactive metal from its compound

31
Q

What is an ionic equation and how do you make one

A

Only particles that react and the proucts they form are shown.
You get the equation
Split it up into seperate elements with the charge on it
See which ones dont change
Get rid of them
Done

32
Q

What is electrolysis

A

When compounds are split using electricity.
Positive ions move towards the negative cathode
Negative ions move towards the positive anode

33
Q

Can solid compounds be electrolysed and why. How do you fix

A

They can not because they are in fixed positions and can’t move. You can either make them molten or dissolve them in water

34
Q

What happens at each electrodes

A

Reduction happens at the cathode
Oxidation happens at the anode

35
Q

Explain the extraction of aluminium from its ore

A

Bauxite (aluminium ore) is mixed with cryolite so it has a lower melting point.
It is melted in an electrolysis chamber
Turns into a molten mixture of Al2O3
The aluminium oxide is electrolysed
The Aluminium goes to the cathode where it is reduced
The Oxygen goes to the anode where it is oxidised

36
Q

What are the half equations for aluminium and oxygen when electrolysed and at which electrode and it is reduction or oxidation

A

Cathode- Al (3+) + 3e(-) –> Al: Reduction
Anode- 2O(2-) –> O2 + 4e(-): Oxidation

37
Q

What is the overall equation for electrolysis (splitting) of aluminium oxide

A

2(Al2O3) –> 4Al + 3O2

38
Q

When a compound cant be melted, how would you perform electrolysis

A

Mix it with water and perform electrolysis with an aqeous solution

39
Q

What are the rules for what is produced for electrolysis in an aqeous solution

A

Cathode-
If less reactive than hydrogen, it will form: e.g. copper
If more reactive than hydrogen, hydrogen will form
Anode-
If there is halide ions, the halide will form, if not then oxygen will form

40
Q

What are the half equations for Hydrogen and water forming in electrolysis

A

Cathode: 2H(+) + 2e(-) –> H2
Anode: 4Oh(-) –> O2 + 2(H2O) + 4e(-)

41
Q

Metal Hydroxide + Acide –>

A

Salt + Water

42
Q

Acid + Metal carbonaate –>

A

Salt + Water + Carbon dioxide

Chemistry (10 decks)

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