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GCSE Chemisty > C4 chemical changes > Flashcards

C4 chemical changes Flashcards

1
Q

Oxidation

A

Metal gains oxygen
Loses electrons to make positive ions
Electrons transferred to oxygen atom to make negative ions
Basic oxide formed

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2
Q

Reduction

A

Loses oxygen

Gains electrons

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3
Q

Most abundant element in earths crust

A

Oxygen
Silicon
Aluminium oxide
Iron 3 oxide

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4
Q

Reactivity with water and dilute acids

A 
Potassium 
Sodium
Lithium
Calcium
Magnesium 
Zinc 
Iron 
Copper
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5
Q

Positive ions

A

First 8 in reactivity series form positive ions

The harder it is to from a positive ion the more reactive it is

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6
Q

Reactivity series

A 
Potassium 
Sodium
Calcium
Magnesium 
Aluminium 
Carbon 
Zinc
Iron
Tin
Lead
Hydrogen 
Copper 
Silver
Gold
Platinum
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7
Q

Displacement reaction

A

When 2 metals react the more reactive metal displaces/ pushes out the less reactive metal

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8
Q

Reduction uses

A

Used to extract metals from their ores

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9
Q

Ores

A

A naturally occurring solid material from which a metal or valuable mineral can be extracted profitably by electrolysis

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10
Q

Making salts

A

Acids react with metals to produce salts and hydrogen

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11
Q

To make a crystallised salt

A

Add excess of substance to acid
Solution needs to be filtered into a crystallising dish
Solution needs to be concentrated by evaporation
Solution then left to evaporate, to crystallise

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12
Q

Redox reaction

A

Both oxidation and reduction occur at the same time

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13
Q

Bases

A

Metal oxides and metal hydroxides
If solvable in water alkalis
Lower concentration of H+ ions

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14
Q

Neutralisation

A

Acid+base}salt+water

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15
Q

Required practical- preparing a pure,dry sample of a soluble salt from an insoluble oxide or carbonate

A

Warm up some acid
Put in powdered metal/base in excess
Filter solution into evaporating dish
Heat till it starts to spit then leave to evaporate and crystallise

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16
Q

Acids

A

Substances that produce hydrogen ions in aqueous solution

Higher concentration of H+ ions lower concentration

17
Q

Required practical- finding the reacting volumes of solutions of acid and alkali by titration

A

Acid in burette
Alkali in pipette to conical flask
Indicator in flask with alkali
Slowly add acid to alkali till indicator changes colour.
Record and try to match result within 0.1
Can find concentration

18
Q

Strong acid

A

In water all of the acid molecules,HA, become ions (H+ and A-)
Ionise completely in water

19
Q

Weak acid

A

In water on,y a few of the acid molecules become ions, most stay as molecules
Do not ionise fully
Equilibrium lies to the left

20
Q

High concentration of H+

A

pH is low

21
Q

Low concentration of H+

A

pH is high

22
Q

Titration curve

A

Rapid fall of pH to the start with, but then slows down
All the alkali is neutralised
Excess acid, pH is below 7

23
Q

Electrolysis

A

The process of passing direct current through a solution or melted ionic compound to move the ions apart and so break the compound down and discharge some of the elements at the electrodes

24
Q

Electrolyte

A

The solution or molten compound

Ions need to be free to move around

25
Q

Cathode

A

Negative electrode

Electrons are gained

26
Q

Anode

A

Positive electrode

Electrons are given up

27
Q

Cations

A

Positive ions attracted to the cathode

28
Q

Anions

A

Negative ions are attracted to the anode

29
Q

Ions discharging

A

All ions migrate towards 2 electrodes
Positive to cathode
Negative to anode

30
Q

Simple binary electrolyte

A

Made up of 2 ions
Eg. Lead bromine or copper chloride
Can conduct electricity if melted

31
Q

Preferential discharge

A

Based on reactivity series

The relatively least reactive ions are preferentially discharged as elements

32
Q

Required practical- investigating what happens when aqueous solutions are electrolysed using inert electrodes

A

Circuit- battery, 2 electrodes
Anode- Cl2, OH-
Cathode- Mg, H+,
Discharged- oxygen and hydrogen

GCSE Chemisty (10 decks)

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