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AH Chemistry > 4. Chemical Changes > Flashcards

4. Chemical Changes Flashcards

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1
Q

What does metal react with oxygen to form?

A

Metal Oxide

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2
Q

Is metal reacting with oxygen an oxidation or reduction reaction?

A

Metal reacting with oxygen is an oxidation reaction as the metal gains oxygen

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3
Q

What is oxidation?

A

Gain of oxygen / Loss of electrons

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4
Q

What is reduction?

A

Loss of oxygen / gain of electrons

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5
Q

What is the reactivity of a metal based on?

A
  • Metals react with substances to form positive ions
  • The reactivity of a metal is based on it’s tendency to lose electrons / to form positive ions
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6
Q

How can we order the metals by their reactivity?

A
  • We can order metals by their reactivity by observing their reactions with water and dilute acids
  • The more reactive the metal, the more vigorous the reaction / more bubbling
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7
Q

What are displacement reactions?

A

A more reactive metal displaces a less reactive metal from a
compound

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8
Q

Reactivity Series

A

Potassium
Sodium
Lithium
Calcium
Magnesium
Aluminium
Carbon
Zinc
Iron
Hydrogen
Copper
Silver
Gold
Platinum

HERE

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9
Q

Reaction of Potassium

  • Comparison
  • What does it react with?
A

Potassium is the most vigorous reaction & burns in water with a lilac flame

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10
Q

Reaction of Sodium

  • Comparison
  • What does it react with?
A

Sodium also reacts vigourously with water (less than potassium) and melts to form a silvery ball before fizzing quickly

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11
Q

Reaction of Lithium

  • Comparison
  • What does it react with?
A

Lithium reacts less vigorously than potassium and sodium in water. It fizzes steadily.

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12
Q

Reaction of Calcium

A

Calcium reacts fast with water at room temperature

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13
Q

Why is dilute acid used to test the reactions of Magnesium, Zinc & Iron?

+ What dilute acids are used?

A

They do not react with water.

+ Hydrochloric or Sulfuric acid

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14
Q

Reaction of Magnesium

  • Comparison
  • What does it react with?
A

Magnesium reacts quickly with dilute acid than Zinc or Iron to form a colourless solution

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15
Q

Reaction of Zinc

  • Comparison
  • What does it react with?
A

Zinc reacts slower than Magnesium with dilute acid to form a colourless solution

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16
Q

Reaction of Iron

  • Comparison
  • What does it react with?
A

Iron reacts slower than Magnesium and Zinc with dilute acid.
It forms a green solution.

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17
Q

Reactions of Copper & Gold

A

Copper and Gold do not react with water or dilute acid

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18
Q

Metal + Water

A

Metal Hydroxide + Hydrogen

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19
Q

Unreactive Metals

A

Unreactive metals such as gold are found in the Earth as the metal itself

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20
Q

What are most metals in the Earth found as?

A

Compounds

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21
Q

How are metals extracted from ores?

A

Metals can be extracted from their ores through chemical reactions:

  • Metals that are less reactive than carbon can be extracted from their oxides/compounds by reduction by heating it with carbon
  • Metals that are more reactive than carbon are extracted by electrolysis
22
Q

Describe the reaction between Copper Oxide & Carbon in terms of oxidation and reduction?

A

Copper + Carbon Dioxide

  • Copper Oxide loses oxygen, so it is reduced
  • Carbon gains oxygen, so it is oxidised
23
Q

MOVE

What are electrolytes?

  • Properties
A

Ionic compounds that are melted or dissolved in water

  • They can conduct electricity as the ions are free to move about
24
Q

What are redox reactions?

A

When reduction and oxidation take place at the same time

25
Q

What is oxidised and what is reduced in this redox reaction:

2H+(aq) + Mg(s) → Mg2+(aq) + H2(g)

A

Mg(s) → Mg2+(aq) + 2e- - Magnesium atoms lose electrons, so they are oxidised

2H+(aq) + 2e- → H2(g) - Hydrogen ions gain electrons, so they are reduced

26
Q

What is an acid?

A

An acid is a substance that produces hydrogen ions (H+) when it is dissolved in an aqueous solution

27
Q

What is an alkali?

A

An alkali is a substance that produces hydroxide ions (OH-) in an aqueous solution

28
Q

What state symbol do acids have and why?

A

(aq) - aqueous solution - as it is dissolved in water

29
Q

Describe the reaction of HCl acid in aqueous solution

A

HCl acid in aqeuous solution forms Hydrogen Ions and Chloride Ions

30
Q

Describe the reaction of Nitric acid in aqueous solution

A

Nitric acid in aqeuous solution forms Hydrogen Ions and Nitrate Ions

31
Q

Describe the reaction of Sulfuric acid in aqueous solution

A

Sulfuric acid in aqeuous solution forms Hydrogen Ions and Sulfate Ions

32
Q

Why is the reaction of Sulfuric acid in aqueous solution a redox reaction?

A
  • Redox reactions are when oxidation and reduction occur at the same time
  • Hydrogen is oxidised as it loses electrons
  • Sulfate is reduced as it gains electrons
33
Q

What do all acids contain?

A

All acids contain Hydrogen

34
Q

What do metals react with acids to produce?

A

Metals react with acids to produce salts and hydrogen

Metal + Acid -> Salt + Hydrogen

35
Q

When can reactions between metals and acids only occur?

A

Reactions between metals and acids can only occur when the metal is more reactive than Hydrogen

as all acids contain hydrogen that needs to be displaced

36
Q

Give an example of a reaction between an acid and metal

A
37
Q

Describe the reactions of magnesium, zinc and iron with acids

A
  • Magnesium reacts the fastest and most vigorously
  • Iron reacts slowly and is the least vigorous
  • This is because it is higher above the reactivity series
  • They are all more reactive than hydrogen
38
Q

What are acids neutralised by?

A

Acids are neutralised by bases, alkalis and metal carbonates

39
Q

Describe the reaction between acids and bases, alkalis and metal carbonates

A
  • acid + alkali -> salt + water
  • acid + base -> salt + water
  • acid + metal carbonate -> salt + water + carbon dioxide
40
Q

What is the main product formed in a neutralisation reaction between an acid & alkali?

A

The hydrogen ions (H+) react with hydroxide ions (OH-) to produce water

H+(aq) + OH-(aq) → H2O(l)

41
Q

What are bases?

A

A base is a substance that reacts with an acid to neutralise it and produce salkt and water ONLY

42
Q

Examples of bases

A

Metal oxides & insoluble metal hydroxides

43
Q

What are alkalis (in terms of bases)?

A

Alkalis are soluble bases

44
Q

Reactions of acids with Metal Oxides, Hydroxides and Carbonates

A
  • Acid + Metal Oxide → Salt + Water
  • Acid + Metal Hydroxide → Salt + Water
  • Acid + Metal Carbonate → Salt + Water + Carbon Dioxide
45
Q

What does the name of the salt depend on?

A

• Positive ions in alkali / base / carbonate
• Acid used (Nitric Acid → Nitrate)

46
Q

How can we make soluble salts?

A
  • Soluble salts can be made from acids by reacting them with solid insoluble substances, such as metals, metal oxides, hydroxides or carbonates
  • If the metal intended to produce is less reactive than hydrogen, you must use a metal oxide, hydroxide or carbonate
  • The solid is added to the acid until no more reacts and the excess solid is filtered off to produce a solution of the salt
47
Q

What is the purpose of the pH scale?

A

The pH scale measures the acidity or alkalinity of a solution

48
Q

What do we use measure the acidity/alkalinity of solutions

A

Universal Indicator or pH probe

49
Q

pH values of acidic, alkaline & neutral solutions

A

• Acidic solutions have a pH value less than 7

• Alkaline solutions have a pH value more than 7

• Neutral solutions have a pH value of 7

50
Q

What is the universal indicator?

A

A mixture of indicators that gives a spectrum of colours to indicate how acidic/alkaline a substance is

AH Chemistry (10 decks)

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