C17 - C19

Question 1

What are some properties of an alkali metal

Answer 1

They are soft

have relatively low melting points

Question 2

Compare the reactions of lithium , sodium and potassium with water

Answer 2

Lithium - fizzes steadily , slowly becomes smaller

Sodium - Melts to form a ball , fizzes rapidly and quickly becomes smaller

Potassium - Quickly melts to form ball , burns with lilac flame

As we go down the group the reactivity increases as the outer electron is lost more easily if the atom is bigger

Question 3

what are the colours and physical states of chlorine , bromine and iodine at room temperature

Answer 3

Chlorine - green , gas
Bromine - brown , liquid
Iodine - Black , solid

As we move down the group halogens go darker in colour

Question 4

Chemical test for chlorine

Answer 4

Chlorine will turn damp blue litmus paper red then white

Question 5

reactivity of halogens

Answer 5

The reactivity will decrease as we go down the group as it is harder for a bigger atom to gain an electron

Question 6

How can we describe noble gasses and where are they used ?

Answer 6

Noble gasses are inert because they have 8 electrons in their outer shell

used in light bulbs and balloons

Question 7

Properties of noble gasses ( trend in group )

Answer 7

Boiling points increases as we go down the group because the atoms become bigger and more forces needed to overcome the forces

Question 8

What are some practical methods for determining rate of reaction ?

Answer 8

change in mass
change in volume
Drawing graphs

Question 9

What happens when there’s an increase in the frequency of collisions

Answer 9

The rate of reaction increases

Question 10

What happens when there is an increase of temperature , pressure or surface area in a reaction ?

Answer 10

If any of these are increased then the rate of reaction increases because the particles are closer together or they will have more energy

Question 11

Describe how a catalyst works

Answer 11

A catalyst will speed up a chemical reaction without being used up , alters the reaction pathway to a lower activation energy

Question 12

what is an exothermic and endothermic reaction

Answer 12

exothermic - heat given out - temperature increases - bonds made

endothermic - heat taken in - temperature decreases - bonds broken

Question 13

Overall heat energy change for a reaction in terms of exothermic and endothermic

Answer 13

exothermic - more energy is released in forming bonds than energy needed in forming bonds so the temperature increases

Endothermic - more energy required to break bonds so temperature decreases

Question 14

Activation energy

Answer 14

The minimum energy required for a reaction to take place