Chapter 8 Reactivity Trends

Question 1

what is the name of the group 2 elements

Answer 1

alkaline earth metals

Question 2

what ions do group 2 elements form

Answer 2

2+ cations

Question 3

explain the reactivity trend in group 2

Answer 3

reactivity increases down the group because it becomes easier to lose electrons due to increased electron shielding and larger atomic radius

Question 4

what type of agent are group 2 elements very good at

Answer 4

reducing agents

Question 5

how does the solubility of group 2 elements change for 1- ions such as OH-

Answer 5

solubility increases down the group

Question 6

how does the solubility of group 2 elements change for 2- ions such as CO3 2-

Answer 6

solubility decreases down the group

Question 7

what is the sulphate ion test

Answer 7

add Barium to the solution and wait to see if a white barium sulphate precipitate

Question 8

what is the metal acid word equation

Answer 8

Metal + Acid –> Salt + Hydrogen

Question 9

what is the metal oxygen word equation

Answer 9

Metal + Oxygen –> Metal oxide

Question 10

how does thermal stability change down a group

Answer 10

thermal stability increases down a group

Question 11

what is the test for a carbonate

Answer 11

add an acid and see if there is any effervesence

Question 12

what is the test for halides

Answer 12

adding AgNO3 first to see a precipitate form

then adding dilute and concentrated ammonia solutions

Question 13

what are three precipitates formed by adding silver nitrate

Answer 13

chloride - white
bromide - cream
iodide - yellow

Question 14

which halide solutions dissolve in dilute ammonia

Answer 14

chloride

Question 15

which halide solutions dissolve in concentrated ammonia

Answer 15

chloride

bromide

Question 16

what colour precipitates do halogens form in water

Answer 16

chlorine - pale green
bromine - orange
iodine - brown

Question 17

what colour precipitates do halogens form in an organic solvent like cyclohexane

Answer 17

chlorine - pale green
bromine - orange
iodine - violet

Question 18

why do halogens in water form two immiscible layers when an organic solvent is added

Answer 18

the two non polar substances halogens and organic solvents form a top layer due to their mutual attraction
meanwhile the two polar substances te halide ions and the water mix to form a bottom layer

Question 19

how and why does oxidising power change in group 7

Answer 19

oxidising power decreases down group 7 due to increased electron shielding and larger atomic radius which decreases the electrostatic attraction

Question 20

what is disproportionation

Answer 20

redox reaction where same element is both oxidised and reduced

Question 21

what is a qualitative test

Answer 21

test where you look for a change that can be observed and then interpreted this could be a colour change for example

Question 22

what is the test for ammonium

Answer 22

add aqueous sodium hydorxide and moist pH indicator paper. If ammonia is present then you should smell ammonia gas and see the indicator turn blue

Question 23

what is the order of qualitative tests

Answer 23

carbonate test
sulphate test
halide test

Question 24

why must the carbonate test be done before the sulphate test

Answer 24

Because Barium + carbonate also forms a white precipitate the same as a sulphate however in the carbonate test only a carbonate would give off effervesence

Question 25

why must the halide test be done last

Answer 25

because both carbonates and sulphates form a white precipitate with the silver ions from silver nitrate solution which would mislead you to think it was chloride

Question 26

if you only had one test tube with a mixture if substances in it was is the first step to identifying the different chemicals inside

Answer 26

do the carbonate test adding excess acid until no more effervesence is produced so that you are sure all carbonate has been removed

Question 27

if you only had one test tube with a mixture of substances in it was is the second step to identifying the different chemicals inside

Answer 27

do the sulphate test to see if a white precipitate forms and add excess barium ions then filter out the precipitate to make sure all sulphate is removed

Question 28

if you only had one test tube with a mixture of substances in it was is the third step to identifying the different chemicals inside

Answer 28

do the halide test adding silver nitrate to see what colour precipitate forms then add ammonia solutions to double check