chemical changes

Question 1

define the oxidation/reduction reaction

Answer 1

Oxidation is gaining oxygen losing electrons
Reduction is loss of oxygen gain of electrons

Question 2

define displacement reaction

Answer 2

more reactive compound displaces a less reactive one from it’s compound

Question 3

Unreactive metals are found in what form?

Answer 3

pure form because they are inert

Question 4

How are metals less reactive then carbon extracted?

Answer 4

Reduced with carbon, carbon displaces the metal oxide, oxygen gets oxidized to carbon dioxide

Question 5

How metals more reactive then carbon extracted?

Answer 5

Electrolysis

Question 6

equation between metals and acids

Answer 6

metal + acid = salt + hydrogen

Question 7

equation for neutralisation

Answer 7

H+ ions + OH- ions = salt + water

Question 8

Equation between metal carbonates and acid

Answer 8

Metal carbonate + acid =salt + water + carbon dioxide

Question 9

what is a redox reaction?
hint re (duction) ox (oxidation)

Answer 9

where both reduction and oxidation occurs

Question 10

How is a soluble salt formed?

Answer 10

1. react the excess acid with some insoluble salt
2. filter off excess with filter paper
3. evaporate over a basin
4. leave solution to crystallize

Question 11

what do acids and alkali’s produce in aqueous solutions?

Answer 11

Acids produce hydrogen ions, alkali’s produce hydroxide ions

Question 12

what is a strong acid/weak acid?

Answer 12

stronger acids- completely ionized when aqueous
weaker acids- only partially ionzied when aqueous

Question 13

what is a concentrated/ diluted acid?

Answer 13

Concentrated acid’s contain more moles of acid then dilute, concentration is not the same as strength, strength is how completely ionsied the H+ Ions are

Question 14

Name this salt K2CO3

Answer 14

potassium carbonate C03 = carbonate salt

Question 15

define electrolysis

Answer 15

an electric current that runs through ionic substances that are molten to break them down into elements, ions are discharged through the positive and negative electrodes in order to do this

Question 16

what is an electrolyte?

Answer 16

the liquid/solution that conducts electricity

Question 17

what is a cathode and an anode?

Answer 17

cathode is the negative electrode, anode is the positive electrode in the electrolysis machine

Question 18

what happens in the cathode and anode during electrolysis?

Answer 18

cathode - reduction
anode - oxidation

Question 19

What is the type of bonding in sodium?

Answer 19

Metallic

Question 20

what observations can you make about the reactivity in group 1

Answer 20

Violent fizzing
Increased bubble production
increased temperature

Question 21

Define the indepenet, dependent, and control variable

Answer 21

Independent - the one that is alterted
Dependent- variable that is being measured
control - Is kept the same to keep results fair

Question 22

evaluate the 3 possible ways to extract tungsten from tungsten oxide (inculde the pro’s and con’s for each method)

Answer 22

Method 1 - displaced using tungsten carbide, some is lost as carbide and c02 escapes
method 2 - Displacing via hydrogen, water vapor will be lost but no separation of solid’s (which is expensive)
Method 3- displacing with iron oxide as it iron is cheap and more reactive

Question 23

explain why sodium oxide has a high melting point?

Answer 23

Is a large ionic lattice
strong electrostatic forces
Large amounts of energy needed to break bonds

Question 24

Properties of transition metals?

Answer 24

High melting points
forms ions with different charges

Question 25

Explain why extraction of aluminum is done by electrolysis instead of displacement via carbon

Answer 25

Carbon is less reactive can’t displace aluminum
can’t carbonize the oxygen atoms of aluminum oxide
lower on the reactivity scale

Question 26

Iron is a transition metal, explain the structural differences between iron and sodium

Answer 26

Iron is more dense
less ductile
higher melting point
can form coloured compounds

Question 27

why do some reactions occur in argon instead of the atmosphere?

Answer 27

Argon is very inert and cannot react with the reaction occuring

Question 28

Why should sodium be kept away from water ?

Answer 28

Causes a highly exothermic reaction, which can be violent or explode

Question 29

defintion of exothermic reactions

Answer 29

They transfer heat to there surroundings

Question 30

Defintion of endothermic

Answer 30

They absorb heat from there surroundings

Question 31

what are bases, acids and alkali’s?

Answer 31

bases are compounds that neutralise acids, Acids produce hydrogen ions in aqueous solutions, alkali’s produce hydroxide ions in aqueous solutions

(aqueous solutions, one’s where the ions are free to move)