FWAQ (frequently wrong answered questions)

Question 1

What is a Hydrocarbon

Answer 1

A compound made up of only hydrogen and carbon only

Question 2

What two words are important in the definition of a hydrocarbon

Answer 2

Compound
Only

Question 3

Give the name of the acid that forms when nitrogen dioxide dissolves in water

Answer 3

Nitric acid

Question 4

Name a pollutant gas that forms from acid rain

Answer 4

Nitric acid
Sulphur dioxide

Question 5

What gas has the highest percentage in dry unpolluted air

Answer 5

Aragon- 0.96

Question 6

Describe how the student should collect a sample of pure oxygen at the positive electrode

Answer 6

Fill a test tube with copper sulfate solution place the tube over the positive electrode

collect gas/oxygen by displacement solution

Question 7

Describe a chemical test other than using an indicator, to show that the reaction mixture contains ethanoic acid

Answer 7

Add carbonate
Effervesces

Add metal
Bubbles/effervesces

Question 8

Explain why the enthalpy change for the reaction between and ester and water =0kj/mol

Answer 8

Same amount of energy is needed to break the bonds in the reactants as is give off

bonds broken= bonds made

Question 9

Describe what is meant by a dynamic equilibrium

Answer 9

Rate forward reaction equals the rate of the backward reaction

concentrations of reactants and products remain constant

Question 10

Explain why adding a catalyst does not change the position of the equilibrium

Answer 10

Increases the rate of forward and backward reaction

equally

Question 11

Definition of a compound

Answer 11

Two different elements which are chemically bonded together

Question 12

Explain how galvanization continues to protect iron when the layer of zinc is damaged

Answer 12

Zinc is a more reactive metal
Zinc corrodes instead of iron

Question 13

Give a reason why the white ring of ammonium chloride takes several minutes to form

Answer 13

gas particles collide with air particles
Gas particles move in random direction
Gas particles collide with wall of tube

Question 14

Explain why argon is highly unreactive

Answer 14

has a complete outer electron shell
Argon does not gain or loose electrons

Question 15

Suggest one reason why the calculated percentage of oxygen in the mixture may not be accurate

Answer 15

Leak in the apparatus
Temperature was not the same for all readings
Apparatus not left to cool

Question 16

Explain why sodium oxide does not conduct electricity

Answer 16

Sodium oxide has ions in a giant ionic structure
no delocalised electrons
ions /electrons can not flow

Question 17

What is the colour of silver precipitate

Answer 17

White

Question 18

Describe the particle arrangement and movement of particles in a gas

Answer 18

Radom arrangement
more freely and quickly in all different directions
far apart

Question 19

suggest how a melting point of a pure substance changes when an impurity is added

Answer 19

Melts over a range of temperatures

Question 20

Explain why cracking is important process int the oil industry.

Answer 20

Crude oil produces long chain of hydrocarbons
Longer chains are less useful
shorter chains are in higher demand as they are more useful

cracking breaks down longer chains into smaller shorter ones

shorter alkanes are flammable more useful in the fuels

alkenes are used to make polymers

Question 21

Describe the forces of attraction in a covalent bond

Answer 21

Strong electrostatic attraction between a nuclei of bonded atoms and a shared pair of electrons

Question 22

what is the word equation for fermentation reaction

Answer 22

Glucose —-> ethanol +carbon dioxide

Question 23

what is meant by the term functional group

Answer 23

group of atoms in a compound that determines it’s chemical properties/ reactions

Question 24

what do the arrows represent in an equilibrium reaction

Answer 24

Reversible reaction
Reaction goes both ways

Question 25

what is an alloy

Answer 25

A mixture of metals