Chapter 5 Chemical Changes Flashcards

1
Q

Write the word equation for the reaction between a metal and oxygen.

A

When metals react with oxygen, metal oxides are formed.

metal + oxygen → metal oxide

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2
Q

What is it called when a metal reacts with oxygen to form a metal oxide OR when an atom loses electrons?.

A

When a metal reacts with oxygen to form a metal oxide this is called oxidation.
Oxidation is also used to describe the loss of electrons.

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3
Q

What 2 things can the term reduction refer to?.

A

When oxygen is lost from a compound in a reaction we call this reduction.
Reduction is also used to describe the gain of electrons.

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4
Q

What does the acronym OIL RIG stand for?

A

OIL RIG can be used to remember what happens to electrons during oxidation and reduction.
Oxidation is loss. Reduction is gain.

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5
Q

What sort of ions do metals always make? Why do they do this?

A

Metals react to form positive ions. This gives them a full outer shell of electrons which makes them more stable.

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6
Q

Are metals that lose electrons more readily more, or less reactive?

A

Metals which lose electrons more readily are more reactive.

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7
Q

What do we call it when we arrange metals in order of reactivity?

A

Metals are arranged in order of reactivity in the reactivity series.

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8
Q

What can we react metals with to determine how reactive they are?

A

The order of reactivity of metals can be determined experimentally by reacting metals with water or dilute acids.

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9
Q

Name 4 metals that will react with water.

A

Potassium, sodium, lithium and calcium will react with water.

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10
Q

Describe in detail what happens when potassium reacts with water.

A

When potassium reacts with water it produces hydrogen gas, melts, explodes and burns with a lilac flame.

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11
Q

Describe in detail what happens when sodium reacts with water.

A

When sodium reacts with water it melts, produces hydrogen gas and may burn with an orange flame.

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12
Q

Describe in detail what happens when lithium reacts with water.

A

When lithium reacts with water it produces hydrogen gas. It doesn’t get hot enough to melt.

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13
Q

Write a word equation for the reaction of a metal with water.

A

When metals react with water hydrogen gas and a salt are produced.

metal + water → salt + hydrogen

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14
Q

Describe how to name salts.

A

When naming salts the first part of the name comes from the metal and the second part comes from the acid.

Eg: magnesium + hydrochloric acid → magnesium chloride + hydrogen gas

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15
Q

Why must equations be balanced?

A

Equations must be balanced so there are the same number of atoms of each element on each side of the equation.

Eg: Mg(s) + 2HCl(aq)→ MgCl2(aq) + H2(g)

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16
Q

Name the 2 non-metals that are included in the reactivity series.

A

The non-metals hydrogen and carbon are included in the reactivity series.

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17
Q

What will metals that are more reactive than hydrogen react with?

A

Metals more reactive than hydrogen will react with dilute acid.

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18
Q

Give the mnemonic for remembering the reactivity series then write out the reactivity series.

A

The reactivity series is:

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19
Q

What is the rule for displacement of metals?

A

A more reactive metal can displace a less reactive metal from solution.

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20
Q

What are the results of displacement reactions used to determine?

A

Results of displacement reactions can be used to determine the reactivity of metals.

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21
Q

What type of reaction are displacement reactions an example of? (higher only)

A

Displacement reactions are redox reactions. One atom is losing electrons while another is gaining electrons.

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22
Q

What type of equations can be used to represent displacement reactions? (higher only)

A

Displacement reactions can be represented using ionic equations.

Eg: Fe(s) + Cu2+(aq) → Fe2+(aq) + Cu(s)

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23
Q

Decide if these half-equations are examples of oxidation or reduction

Fe(s) → Fe2+ + 2e-
Cu2+(aq) +2e- → Cu(s)
(higher only)

A

Ionic equations for redox reactions can be represented by 2 half-equations to show what happens to each reactant.

Eg: Oxidation Fe(s) → Fe2+ + 2e-
Reduction Cu2+(aq) +2e- → Cu(s)

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24
Q

What do you get when you put together 2 half-equations? What must be true of the electrons in this final equation? (higher only)

A

The 2 half-equations can be put together to make the ionic equation. The number of electrons on the right must equal the electrons on the left.

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25
Q

What element is displaced when metals react with acid? (higher only)

A

When metals react with acids a type of displacement reaction is taking place but this time hydrogen is displaced. Only metals more reactive than hydrogen will react with acids because they are displacing hydrogen so need to be more reactive than hydrogen.

26
Q

Give the ion-electron half-equations for the displacement of hydrogen when magnesium reacts with hydrochloric acid. State which is oxidation and which is reduction. (higher only)

A

Ion-electron equations for the displacement of hydrogen when Mg reacts with HCl:
Oxidation Mg(s) → Mg2+ + 2e-
Reduction 2H+(aq) +2e- → H2(g)

27
Q

How are most metals found in the Earth’s crust?

A

Most metals are found as compounds in the Earth’s crust.

28
Q

What do we call a metal compound that contains enough metal to make it economic to extract?

A

A metal compound that contains enough metal to make it economic to extract is known as an ore.

29
Q

Why is gold found unreacted in the Earth’s crust?

A

Gold is so unreactive that it is found uncombined in the Earth’s crust.

30
Q

How can metals less reactive than carbon be extracted? What is formed?

A

Metals less reactive than carbon in the reactivity series can be extracted by heating them with carbon. The carbon ‘grabs’ the oxygen and forms carbon dioxide.

31
Q

Give the word equation for the extraction of a metal using carbon.

A

Equation for the extraction of a metal using carbon:

metal oxide + carbon → metal + carbon dioxide

32
Q

Give the word and chemical equations for the reduction of tungsten oxide by hydrogen. Include state symbols.

A

Some metal oxides can be reduced by heating with hydrogen.

Eg: tungsten oxide + hydrogen → tungsten + water
WO3(s) + 3H2(g) → W(s) + 3H2O(g)

33
Q

How can metals more reactive than carbon be extracted from their ores?

A

Metals more reactive than carbon need to be extracted from their ores using electrolysis of the molten metal compound. (You will learn more about electrolysis later in the course).

34
Q

What tool do we use to decide on the best extraction method for a metal from its ore?

A

The reactivity series can be used to decide which extraction method is best

35
Q

What is a salt?

A

A salt is a compound formed when the hydrogen in an acid is wholly or partially replaced by metal or ammonia ions.

36
Q

How can a salt be produced from a metal?

A

Salts can be made by reacting a suitable metal with an acid as long as the metal is higher than hydrogen in the reactivity series.

37
Q

Copy and complete the table to show which metals and acids are used to make the salts listed.

A

Acids and metals can be chosen to prepare the salt you need.

38
Q

Describe in detail the stages involved in the production of a soluble salt from a metal and an acid.

A

Producing a soluble salt from a metal and an acid:
1. Add powdered metal to acid.

  1. Keep adding the powdered metal until no more hydrogen is produced.
  2. Filter the excess metal from the products.
  3. Place the filtrate containing the salt in an evaporating basin.
  4. Gently heat to remove water.
  5. Crystals of the salt will form. This is called crystallisation.
39
Q

Give the word equation for a neutralisation reaction between an acid and a base.

A

Acids react with bases in neutralisation reactions.

acid + base → salt + water

40
Q

What 3 types of compounds are considered bases?

A

Bases are metal oxides, metal carbonates and metal hydroxides.

41
Q

What are alkalis?

A

Alkalis are soluble bases.

42
Q

How can the formula of a salt be determined?

A

The charges on ions in a salt can be used to work out the formula of the salt.

43
Q

How can the charge on ions of transition metals be determined?

A

Transition metals can form more than one type of ion. The charge on a transition metal can be determined from its name. Roman numerals are used to indicate the charge on the ion.

44
Q

Complete the table to give the formula and charge for each complex ion.

A

There are complex ions that have a single charge on a group of atoms. These can be found in acids and carbonates.

45
Q

Give the word equation for the neutralisation reaction between an acid and a metal oxide.

A

The neutralisation reaction between an acid and a metal oxide is:
acid + metal oxide → salt + water

46
Q

Give the word equation for the neutralisation between an acid and a metal hydroxide.

A

The neutralisation between an acid and a metal hydroxide is:

47
Q

Give the word equation for the neutralisation reaction between an acid and a metal carbonate.

A

The neutralisation reaction between an acid and a metal carbonate is:
acid + metal carbonate → salt + water + carbon dioxide
Eg: hydrochloric acid + calcium carbonate → calcium chloride + water + carbon dioxide
H+Cl + Ca2+CO32- → CaCl2 + H2O + CO2

48
Q

Describe in detail the stages involved in the production of a soluble salt from a metal carbonate.

A

To make a salt from a metal carbonate:
1. Add the metal carbonate to the acid until it stops fizzing (producing carbon dioxide).

  1. Filter to remove any excess carbonate.
  2. Place the filtrate in an evaporating basin.
  3. Heat gently to remove the water
  4. Crystals of your salt will form. This is called crystallisation.
49
Q

What is an acid?

A

An acid is a chemical that produces a H+ ions in aqueous solutions.

50
Q

What is an alkali?

A

An alkali is a chemical that produces OH- ions in aqueous solutions.

51
Q

Write the chemical equation for the production of water in a neutralisation reaction. Include charges and state symbols.

A

In a neutralisation reaction the H+ from the acid reacts with the OH- from the alkali to produce H2O.
H+(aq) + OH-(aq) → H2O(l)

52
Q

What does the pH scale measure? What range in values does it have?

A

The pH scale goes from 1 to 14 and measures how acid or alkaline a solution is.

53
Q

What colour does universal indicator change in a solution of each pH?

A

When universal indicator is used to measure pH the following scale is produced:

54
Q

Other than universal indicator what else can be used to measure pH?

A

A pH probe can also be used to measure pH.

55
Q

What are strong acids? (higher only)

A

Strong acids are acids that completely dissociate (turn into ions) in water.

56
Q

Give 3 examples of strong acids.(higher only)

A

Nitric acid, sulfuric acid and hydrochloric acid are all strong acids.

57
Q

What makes an acid a weak acid?(higher only)

A

Weak acids only partially dissociate (turn into ions) in water.

58
Q

Give 3 examples of weak acids.(higher only)

A

Ethanoic acid, carbonic acid and citric acid are all weak acids.

59
Q

Do strong acids have higher or lower pH values than weak acids? (higher only)

A

The stronger the acid is the lower the pH will be.

60
Q

How are the terms strong and weak different from the terms dilute and concentrated when referring to acids?
(higher only)

A

Acids can be classified as strong and weak. This is not the same as being concentrated or dilute. How concentrated an acid is depends on the number of particles in a certain volume. You can have a concentrated solution of a weak acid (2M citric acid) or a dilute solution of a strong acid (0.01M HCl).

61
Q

The pH scale is logarithmic. What does this mean? (higher only)

A

The pH scale is logarithmic. This means that as the pH decreases by 1 the concentration of H+ ions increases by 10X.