Chemical changes: reactivity of metals and reactions of acids - Summary

Question 1

Q: What is the general reaction between a metal and an acid?

Answer 1

Metal + Acid → Salt + Hydrogen

Question 2

Q: What observations indicate reactivity?

Answer 2

Fizzing/bubbles (hydrogen) (effervescence)

Temperature rise

Speed of reaction

Question 3

Q: Which metals react with dilute hydrochloric/sulfuric acid?

Answer 3

Metals above hydrogen in the reactivity series (e.g., Mg, Zn, Fe)

Question 4

Q: What salt forms when magnesium reacts with sulfuric acid?

Answer 4

Magnesium sulfate

Question 5

Q: How can you test for hydrogen gas?

Answer 5

Lit splint → squeaky pop

Question 6

Q: What is corrosion?

Answer 6

Reaction of metal with substances in environment (e.g., oxygen, water)

Question 7

Q: What is the word equation for rusting?

Answer 7

Iron + Water + Oxygen → Hydrated iron(III) oxide

Question 8

Q: What are the conditions needed for rusting?

Answer 8

Presence of both oxygen and water

Question 9

Q: How can rusting be prevented?

Answer 9

Barrier methods: paint, oil, plastic coating

Sacrificial protection: attaching more reactive metal (e.g., zinc)

Question 10

Q: What is galvanising?

Answer 10

Coating iron/steel with zinc to prevent rusting (barrier + sacrificial)

Question 11

Q: What is a displacement reaction in terms of metals?

Answer 11

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

Question 12

Q: Example of metal displacement:

Answer 12

Zinc + Copper sulfate → Zinc sulfate + Copper

Question 13

Q: What does the reactivity series look like (top 10 metals)?

Answer 13

Potassium > Sodium > Calcium > Magnesium > Aluminium > (Carbon) > Zinc > Iron > Tin > Lead > (Hydrogen) > Copper > Silver > Gold > Platinum

Question 14

Q: What is the role of carbon in the series?

Answer 14

Metals below carbon can be extracted by reduction with carbon

Question 15

Q: What is observed during displacement?

Answer 15

Colour change, temperature change, metal deposited

Question 16

Q: How are metals below carbon in the reactivity series extracted?

Answer 16

By heating with carbon (reduction)

Question 17

Q: What is bioleaching?

Answer 17

Bacteria break down ore → solution (leachate) containing metal ions

Question 18

Q: What is phytomining?

Answer 18

Plants absorb metal ions from soil → burned → ash contains metal compounds

Question 19

Q: Advantages of bioleaching/phytomining?

Answer 19

Low energy

Extracts from low-grade ores

Less environmental damage than traditional mining

Question 20

Q: Disadvantages of bioleaching/phytomining?

Answer 20

Slow

Produces toxic substances (bioleaching)

Question 21

Q: What is the pH scale?

Answer 21

Measures concentration of H⁺ ions (0 = strong acid, 14 = strong alkali)

Question 22

Q: What is a neutralisation reaction?

Answer 22

Acid + Base → Salt + Water

Question 23

Q: What do acids release in aqueous solution?

Answer 23

H⁺ ions

Question 24

Q: What do alkalis release in solution?

Answer 24

OH⁻ ions

Question 25

Q: What are indicators used for?

Answer 25

To show pH — universal indicator gives full range of colours

Question 26

Q: What is a titration used for?

Answer 26

To determine the exact volume of acid/alkali needed for neutralisation

Question 27

Q: What are the key steps of a titration?

Answer 27

Add acid to burette Pipette alkali into conical flask with indicator Add acid dropwise until indicator changes colour (end point) Repeat for accurate results

Question 28

Q: Which indicator is used and why?

Answer 28

Phenolphthalein (pink in alkali, colourless in acid) or methyl orange

Question 29

Q: What is a concordant result?

Answer 29

Titre values within 0.1 cm³ of each other

Question 30

Q: Example neutralisation reaction:

Answer 30

HCl + NaOH → NaCl + H₂O

Question 31

Q: What is the reaction between an acid and a metal oxide?

Answer 31

Acid + Metal Oxide → Salt + Water

Question 32

Q: What is the reaction between an acid and a metal carbonate?

Answer 32

Acid + Metal Carbonate → Salt + Water + Carbon Dioxide

Question 33

Q: How can you test for CO₂?

Answer 33

Bubble through limewater → turns cloudy

Question 34

Q: What’s the method for making a pure, dry salt from an insoluble base?

Answer 34

Warm acid Add excess base until no more reacts Filter excess Heat filtrate to evaporate water Leave to crystallise

Question 35

Q: Why use an excess of the base?

Answer 35

To ensure all acid reacts and no acid remains in final product

Question 36

Q: Which metals can be extracted using carbon?

Answer 36

Metals below carbon in reactivity series (e.g., Zn, Fe, Cu)

Question 37

Q: How does the reactivity series relate to extraction methods?

Answer 37

More reactive metals require electrolysis Less reactive = reduction

Question 38

Q: Why is titration important in chemistry?

Answer 38

Allows accurate preparation of neutral solutions and analysis of concentrations

Question 39

Q: Why do metals higher in the series react more violently with acids?

Answer 39

More easily lose electrons (form positive ions)

Question 40

Q: What does it mean if a reaction is a redox reaction?

Answer 40

Involves both reduction (gain of electrons) and oxidation (loss of electrons)