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Chemistry > Topic 4 - Chemical Changes > Flashcards

Topic 4 - Chemical Changes Flashcards

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1
Q

acid + alkali ->

A

acid + alkali -> salt + water

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2
Q

Acid + Metal →

A

Acid + Metal → Metal salt + hydrogen(g)

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3
Q

Acid + Metal Carbonate →

A

Acid + Metal Carbonate → Metal salt + carbon dioxide + water

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4
Q

Acid + metal oxide →

A

Acid + metal oxide → Salt + Water

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5
Q

metal + oxygen →

A

metal + oxygen → metal oxide

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6
Q

What is the name given to a reaction that involves losing oxygen?

A

reduction

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7
Q

REACTIVITY SERIES

purple
slime
can
make
a 
careless
zebra
insane
try 
learning
how
camels
surprise
gorilla
parties
A 
Potassium
Sodium
Calcium
Magnesium
Aluminium
(Carbon)
Zinc
Iron
Tin
Lead
(Hydrogen)
Copper
Silver
Gold 
Platinum
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8
Q

describe the observations of water reacting with potassium, lithium, sodium

A

Potassium, sodium and lithium all react quickly with cold water to produce a metal hydroxide and hydrogen gas.
2
Potassium
Potassium is the most reactive so reacts very quickly. The hydrogen produced ignites instantly and the metal also sets alight, sparking and burning with a lilac flame.
3
Sodium
Sodium fizzes rapidly and melts to form a ball that moves around on the water surface.
4
Lithium
Lithium fizzes steadily and floats, becoming smaller until it eventually disappears.

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9
Q

when do displacement reactions occur?

A

Displacement reactions occur when a more reactive metal reacts to displace a less reactive metal in a compound.

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10
Q

When zinc is reacted with calcium carbonate, no reaction occurs. Explain why.

A

Zinc does not react with calcium carbonate because zinc is not as reactive as calcium.

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11
Q

what are all the diatomic elements?

A 
Hydrogen (H2)
Nitrogen (N2)
Oxygen (O2)
Fluorine (F2)
Chlorine (Cl2)
Iodine (I2)
Bromine (Br2)
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12
Q

what group are halogen ?

A

7

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13
Q

describe what happens at each electrode in electrolysis in aqueous solutions

A

At the cathode (negative electrode)

What is formed at the cathode depends on the reactivity of the metal:
Hydrogen is produced if the metal is higher than hydrogen in the reactivity series.
The metal is produced if the metal is lower than hydrogen in the reactivity series.

At the anode (positive electrode)

What is formed at the anode depends on if there are halide ions present:
If there are halide ions present, the respective halogen forms.
If there are no halide ions, oxygen forms.

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14
Q

does reduction or oxidation take place at the anode?

A

oxidation

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15
Q

does reduction or oxidation take place at the anode?

A

oxidation

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16
Q

does reduction or oxidation take place at the cathode?

A

reduction

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17
Q

An aqueous solution of copper(II) sulfate (CuSO4) contains Cu2+, SO42-, H+ and OH- ions. What happens when it is electrolysed?

A
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18
Q

What characterises a more reactive metal?

A

a metal that forms positive ions more easily

19
Q

Which of the following would you observe when adding potassium to water?

A

lilac flame
very quick reaction
sparks

20
Q

Give 2 reasons why carbon is used to extract metals from their oxides:

A

1Carbon is cheap
2Carbon is abundant
3 cheap

21
Q

State 2 metals that would react with dilute acid but not water.

A 
Magnesium
Zinc
Iron
Aluminium
Lead
22
Q

what are the obsevations when sodium is added to water?

A

melts into a ball
lots of fizzing
orange flame
moves around on surface

23
Q

what are the observations when lithium is added to water?

A

floats on surface
fizzes steadily
gets smaller and smaller

24
Q

what are the observations when calcium is added to water?

A

fizzing

cloudy precipitate

25
Q

Describe strong acids

A

•Ionise completely in water
•All acid particles dissociate to release H+ ions
= higher conc of H+ ions so rate of reaction
will be faster.

26
Q

Describe weak acids

A

-Don’ t fully ionise in solution
- only small number of acid particles dissociate to
release H+ ions
. The ionisation of weak acid is a reversible
reaction,which sets up an equilibrium between the
undissociated and dissociated acid. Due to only
a few of the acid particles release H+ ions, the
position at equilibrium lies to the left

27
Q

What is pH?

A

measure of the conc of H+ ions in solution.
For every decrease of 1 on pH scale H+ ions
increase by a factor at 10.
so pH 4 acid has ten times more conc of H+
Ions as pH 5 acid.
Factor H+ ion conc changes by = 10^-x

So if ph decreased from 5 to 2 there would be a decrease of -3 so 10^-(-3)+ 10^3

28
Q

Which factor determines the reactivity of a metal?

A

How easily the atoms of that element lose their outer electrons

29
Q

what is a displacemtn reaction?

A

When a more reactive metal displaces a less reactive metal

30
Q

Which group of metals are the most reactive?

A

Group 1

31
Q

When metals react, do the atoms become positive or negative ions?

A

positive

32
Q

In electrolysis, which direction do the electrons travel?

A

Anode ➔ Cathode

33
Q

The electrodes in an electrolysis cell are normally made of inert carbon. What does the term ‘inert’ mean?

A

It is unreactive, so will not take place in the reaction.

34
Q

In electrolysis, why does the compound you’re trying to separate need to be molten or dissolved?

A

So that the ions are free to move around (and go to their respective electrode)

35
Q

Why is electrolysis not used to extract all metals?

A

Electrolysis is expensive because it requires a large amount of electricity, metals less reactive than carbon can be reduced

36
Q

Why is electrolysis used to extract aluminium from its ores?

A

more reactive than carbon

37
Q

What is the name of the substance that is mixed with aluminium oxide to lower its melting point?

A

Cryolite

38
Q

Balance the equation below for the separation of aluminium from oxygen.
Al2O3 ➔ Al + O2

A

2Al2O3 ➔ 4Al + 3O2

39
Q

In the electrolysis of aqueous solutions, what is the rule for determining which ion will be oxidised (lose electrons) at the anode (positive electrode)?

A

It will always be the OH-, unless there is a halide ion (such as Cl-, or Br-) present
remember all halide ions are diatomic

40
Q

In the electrolysis of aqueous solutions, what is the rule for determining which ion will be reduced (gain electrons) at the cathode (negative electrode)?

A

It will always be the H+ ion, unless Cu2+ is present (another way of phrasing it would be that it is always the ion of the least reactive element)

41
Q

In the electrolysis of aqueous sodium chloride, NaCl (aq), which four ions would be present in the electrolyte?

A

Sodium ions (Na+)

Chloride ions (Cl-)

Hydrogen ions (H+)

Hydroxide ions (OH-)

42
Q

In the electrolysis of aqueous sodium chloride, NaCl (aq), which of the four ions will be oxidised at the anode (positive electrode)?

A

Chloride ions (Cl-)

43
Q

In the electrolysis of aqueous sodium chloride, NaCl (aq), which of the four ions will be reduced at the cathode (negative electrode)?

A

Hydrogen ions (H+)

Chemistry (8 decks)

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