Incorrect from past paper 1

Question 1

Why is sodium not suitable for an electrode in water (or an electrolyte)

Answer 1

sodium would react with the electrolye/water

Question 2

Why is sulfur not suitable for an electrode in water (or an electrolyte)

Answer 2

It doesnt conduct electricity

Question 3

what happens during a reaction where a solution goes from acidic to alkali

Answer 3

neutralisation happens in the REACTION part (ie: H+ + OH- -> H2O)

at the start, ph is low
at the end ph is high

were talking abt the REACTION

Question 4

What are qualities of the melting point of transition metals and their colour when they melt

Answer 4

They have coloured compounds, so they will be a colour (ie: orange instead of white) when melting

the MP is very high

Question 5

Why is % yield never 100%

Answer 5

incomplete reaction

loss {of substance/reactant/product} (during practical)/ practical losses

unwanted reactions/ side-reactions

Question 6

Nitrogen is

Answer 6

Diatomic

Question 7

Where is copper formed during the electrolysis? and why

Answer 7

At the cathode

this is because copper ions are positive so are reduced (gain electrons) at the cathode

Question 8

When a q asks to describe/EXPLAIN a trend what must you talk about (if its worth the marks)

Answer 8

the overall statement (ie: current is direct prop to mass)

Because…

So…

Question 9

A student investigates the mass of copper produced when copper chloride solution in a beaker is electrolysed using inert electrodes.

Describe how, after the power supply has been switched off, the mass of copper formed can be measured.

Answer 9

(rinse and) dry {electrode / cathode} (1)

measure mass of {electrode/ cathode} (on a balance) (and subtract original mass) (1)

Question 10

State the name of the two reactants that are neutralised to make the salt ammonium nitrate.

Answer 10

Ammonia and nitric acid

Question 11

What results do you use for calculating mean titre

Answer 11

Excluding rough titre, everything in between 0.1cm^3 of each other

Question 12

what are tips for using a burette

Answer 12

• rinse the burette with titrant (1)
• fill the jet / tip (1)
• do not fill burette over 0 cm3/ overfill/ run liquid out until volume at or below 0 cm3
• add drop by drop only near {end point/ colour change} (1)

Question 13

In a titration a student placed alkali in the flask.

By mistake a few drops of litmus and a few drops of phenolphthalein were added to the flask.

The student added acid to the flask until the mixture was acidic.

Predict the colour change that would be seen

Answer 13

from: pink-blue/ pink-purple/ blue-purple/ purple
to red

Question 14

In a titration a student rinsed out the flask with distilled water and did not dry it.

They used the flask for titration, adding the solution from the burette until the indicator changed colour.

State the effect, if any, on the titre volume of using the wet flask rather than a dry flask.

Answer 14

none

Question 15

When youre adding CuO to warm dilute sulfuric acid in spatulas, how do yk when you have got the right amount

Answer 15

You add one spatula, stir and see that it dissolves

repeat that until none of the mixture mixes and it sits on the bottom (OBSERVATION)

there is an excess of copper oxide (COPPER OXIDE)

all the acid {is neutralised/ has reacted}/ no
acid remains (ACID)

Question 16

What is the best way to obtain crystals of copper sulfate from an
aqueous solution?

Answer 16

heat the solution using a water bath

Question 17

Describe Sodium Chloride in terms of bonding, structure and energy etc

Answer 17

SODIUM CHLORIDE
* ionic compound
* giant lattice
* positive (sodium) ions and negative (chloride) ions
* strong electrostatic attraction between ions
* lots of energy to overcome attraction/ bonds

Question 18

Describe Water in terms of bonding, structure and energy etc

Answer 18

WATER
* simple covalent/ molecular
* strong covalent bonds between atoms in a molecule
* weak forces between molecules
* little energy needed to overcome the intermolecular forces

Question 19

State what is meant by the term corrosion.

Answer 19

• reaction of a metal (1)
• with oxygen/ oxidation (1)

Question 20

3 Metal properties

Answer 20

METAL PROPERTIES
* good conductors of electricity/heat
* malleable
* ductile

Question 21

3 Alloy properties

Answer 21

ALLOY PROPERTIES
* good conductors of heat/electricity
* malleability is lower than pure metal
* specific properties of magnalium e.g. low density (ignore light)

Question 22

2 metals and their uses

Answer 22

METAL USES
* aluminium for cooking foil, food trays
* copper for water pipes, electrical wires, roofing

Question 23

2 alloys and their uses

Answer 23

ALLOY USES
* aluminium alloys for aircraft parts, vehicles, ladders
* copper alloys for coins, brass instruments, jewellery, plug prongs

Question 24

COMPARE/ SIMILARITIES between metal and alloy

Answer 24

• both exist as lattices of ions with delocalised electrons
• conduct heat because delocalised electrons in both to carry thermal energy
• high melting and boiling points due to strong metallic bonds

Question 25

CONTRAST/ DIFFERENCES between metal and alloy

Answer 25

* harder for layers to slide therefore alloys typically stronger, less malleable and less ductile * alloys can be more corrosion resistant * metals have fixed melting point but alloys a range as a mixture

Question 26

Differences between methyl orange Litmus paper Phenolphthalein indicators

Answer 26

Phenolphthalein ○ Alkaline = pink ○ Acidic = colourless ● Methyl orange ○ Alkaline = yellow ○ Acidic = red ● Litmus paper ■ Blue litmus paper goes red in acidic & stays blue in alkaline ■ Red litmus paper goes blue in alkaline & stays red in acidic