p1 exam Q

Question 1

in titration, explain why u should use a pipette to measure the acid and a burette to measure the alkali (2)

Answer 1

pipette measures a fixed volume, a burette measures variable volume

Question 2

A student obtains a powdery white solid. Suggest how he could obtain large crystals (2)

Answer 2

Evaporate some of the solution and leave to cool

Question 3

whilst making salts explain why u would add excess zinc rather than excess iodine (3)

Answer 3

To make sure all the iodine reacts. Excess iodine would remain in the solution. So the iodine could not be filtered off

Question 4

Explain what is meant by a weak acid (2)

Answer 4

Produces hydrogen ions in aqueous solutions but partially ionises

Question 5

the atomic weight of Te is 128 and I is 127. why did Mendeleev reverse the order of these two elements? (1)

Answer 5

Iodine (I) has similar properties to group 7

Question 6

why did Mendeelev’s periodic table become more widely accepted than previous version? (3)

Answer 6

mendeleev predicted the properties of missing elements. elements were later discovered that filled the gaps. their properties matched mendeleevs predictions.

Question 7

what is the modern term for atomic weight?

Answer 7

relative atomic mass

Question 8

describe what you would see when sodium reacts with chlorine (2)

Answer 8

flame, white solid forms

Question 9

suggest one reason why it costs less to use nanoparticles rather than fine particles in sun creams (2)

Answer 9

less can be used to achieve the same effect. as there is a greater surface area to volume ratio.

Question 10

some trains run on hydrogen fuel cells. an article referred to them as the new steam trains. suggest why. (2)

Answer 10

in the fuel cell hydrogen is oxidised and water is produced as vapour

Question 11

give 2 reasons why the discovery of gallium helped mendeleevs periodic table to become accepted? (2)

Answer 11

gallium fitted in the gap mendeleev had left, galliums properties were predicted correctly by Mendeleev.

Question 12

explain why the reactivity of the elements changes going down group 1 (4)

Answer 12

• reactivity increases as you go down
• as the atoms get larger as you go down the distance between nucleus and outer electron increases
• weakens the force of attraction between positive nucleus and negative outer electron
• which makes it easier to lose

Question 13

explain why sodium oxide has a high melting point (3)

Answer 13

it is a giant structure. with strong electrostatic forces of attraction between oppositely charged ions. which require a lot of energy to overcome.

Question 14

in the electrolysis of copper nitrate solution some copper produce did not stick to the electrode but fell to the bottom .explain how you can find total mass of copper produced. (4)

Answer 14

filter the mixture. wash and dry the copper residue. weigh the copper collected. add to the increase in mass of the electrode.

Question 15

iron is a transition metal. sodium is a group 1 metal. give 2 differneces in properties.

Answer 15

iron is denser. iron is stronger.

Question 16

explain why carbon can be used to extract nickel from nickel oxide. (2)

Answer 16

carbon is more reactive than nickel. so carbon will displace nickel from nickel oxide.

Question 17

alkaline batteries are non-rechargeable. why do alkaline batteries eventually stop working? (1)

Answer 17

the reactants get used up

Question 18

why can alkaline batteries not be re-charged?

Answer 18

the reaction is not reversible

Question 19

Chadwick’s experimental work on the atom led to a better understanding of isotopes. explain how his work led to this understanding. (3)

Answer 19

he provided evidence to prove existence of neutrons. this was necessary as isotopes have the same numbers of protons, but with different numbers of neutrons.

Question 20

titanium is extracted from titanium dioxide. stage 2 of this involves the reaction between titanium chloride and sodium to produce titanium and sodium chloride. suggest why this was done in an atmosphere of argon and not in air. (2)

Answer 20

argon is inert. oxygen from the air would react with the titanium.