C4 Chemical Changes

Question 1

<p>What ion do Alkalis form when they dissolve in water?</p>

Answer 1

<p>Alkalis form hydroxide (OH^-) ions when they dissolve in water</p>

Question 2

<p>What ions do Acids form when they dissolve in Water?</p>

Answer 2

<p>Acids form hydrogen (H⁺) ions when they dissolve in water</p>

Question 3

<p>How do Acids and Alkali neutralise each other?</p>

Answer 3

<ul><li>Acids form hydrogen (H⁺) ions when they dissolve in water</li><li>Alkalis form hydroxide (OH^-) ions when they dissolve in water</li><li>When an acid and alkali mix, the H⁺ of the acid and OH^- ions of the alkali combine to form H₂O, otherwise known as water</li><li>Water is a neutral substance so an acid and an alkali neutralise each other</li></ul>

Question 4

<p>What is <b>Oxidation</b>?</p>

Answer 4

<p>Oxidation a reaction involving the gain of oxygen. Oxidation is also the loss of electrons</p>

Question 5

<p>What is <b>Reduction</b>?</p>

Answer 5

<p>Reduction is a reaction involving the loss of oxygen. It is also the gain of electrons</p>

Question 6

<p>What are <b>Redox</b> Reactions?</p>

Answer 6

<p>Redox reactions is when one substance undergoes reduction and the other substance undergoes oxidation</p>

Question 7

<p>What is the reactivity Series?</p>

Answer 7

<p>The reactivity series is a list of element planced in order of reactivity</p>

Question 8

<p>List the reactivity series in order from most reactive to least reactive</p>

Answer 8

<ul><li>Potassium (Most Reactive)</li><li>Sodium</li><li>Lithium</li><li>Calcium</li><li>Magnesium</li><li>(Carbon)</li><li>Zinc</li><li>Iron</li><li>(Hydrogen)</li><li>Copper (Least Reactive)</li></ul>

Question 9

<p>What are <b>displacement reactions?</b></p>

Answer 9

<p>A displacement reaction more reactive metal (one that forms positive ions more easily) can replaces a less reactive metal from a compound</p>

Question 10

<p>When can a displacement reaction take place?</p>

Answer 10

<p>A metal can only displace another metal from a compound if it is located above it in the reactivity series</p>

Question 11

<p>What are spectator ions?</p>

Answer 11

<p>Spectator ions are the ions in a displacement reaction that reamin unchanged in the reaction</p>

Question 12

<p>What are the highly unreactive metals that are found in the Earth's crust called?</p>

Answer 12

<p>Native Metals</p>

Question 13

<p>What are group 1 elements called Alkali Metals?</p>

Answer 13

<p>When group 1 metals react with water, the solution is Alkaline</p>

Question 14

<p>What is produced when reactive metals react with water?</p>

Answer 14

<ul><li>Metal Hydroxide</li><li>Hydrogen Gas</li></ul>

Question 15

<p>What is produced when metals react with dilute acids?</p>

Answer 15

<ul><li>A Salt</li><li>Hydrogen Gas</li></ul>

Question 16

<p>Why is carbon used to extract metals?</p>

Answer 16

<p>Reducing a metal with carbon will result in the extraction of the metal if the metal is lower in the reactivity series than carbon.
Carbon is used because it is cheap and abundant</p>

Question 17

<p>How is carbon used to extract metals?</p>

Answer 17

<p>In the reduction, the metal oxide loses oxygen to form a pure metal
Reduction with carbon normally involves heating the metal oxide in the presence of the carbon, which is often used in the form of coal</p>

Question 18

<p>Which metals react with dilute acids but not cold water?</p>

Answer 18

<ul><li>Magnesium</li><li>Aluminium</li><li>Zinc</li><li>Iron</li><li>Lead</li></ul>

Question 19

<p>What happens when an acid reacts with a metal carbonate?</p>

Answer 19

<p>Acid + Metal Carbonate → Salt + Water + Carbon Dioxide</p>

Question 20

<p>What happens when an acid reacts with a metal oxide?</p>

Answer 20

<p>Acid + Metal oxide → Salt + Water</p>

Question 21

<p>What happens when an acid reacts with a metal?</p>

Answer 21

<p>Acid + Metal → Salt + Hydrogen</p>

Question 22

<p>What happens when an acid reacts with a metal hydroxide?</p>

Answer 22

<p>Acid + Metal hydroxide → Salt + Water</p>

Question 23

<p>What is the method to produce a pure, dry sample of a soluble salt from an insoluble oxide or carbonate?</p>

Answer 23

<ul><li>Gently warm an acid using a bunsen burener and continually add the insoluable solid, whilst stirring, till no more reacts</li><li>Filter the solution to remove any excess insoluble solid</li><li>Heat the solution in an evaporating basin above a beaker of water - the beaker of water ensures a gentle heating</li><li>Leave the solution to cool - As the water evaporates, the solution becomes concentrated which allows the salt to crystalise</li></ul>

Question 24

<p>What are two ways to measure pH?</p>

Answer 24

<ul><li>Universal Indicator</li><li>pH Probe</li></ul>

Question 25

<p>What does the pH of an chemical tell you?</p>

Answer 25

<p>The pH tells you the concentration of H⁺ ions in a solution</p>

Question 26

<p>What happens to the concentration of H⁺ ions every time the pH increases by 1?</p>

Answer 26

<p>As the pH increases by 1, the concentration of H⁺ divides by 10</p>

Question 27

<p>What is the concentration of H⁺ ions at pH 0?</p>

Answer 27

<p>1 mol/dm³</p>

Question 28

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Answer 28

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