3C - Halide tests |
1) State and explain the reactivity of the halogens as you go down Group 7: [4]
More reactive down the group [1] Due smaller atom [1]
Less shielding [1] Greater attraction to capture an electron [1]
2) This question is about the tests of the potassium halides.
a) Complete the table below putting in the colours of the halides when silver nitrate is added [6]
Halogen |
Colour with AgNO3 |
Addition of dil / conc ammonia |
Chlorine |
White precipitate |
Precipitate dissolves in dil |
Bromine |
Cream precipitate |
Precipitate dissolves in conc |
Iodine |
Yellow precipitate |
Precipitate does not dissolve |
b) Write equations for the 3 precipitate reactions [3]
Balanced equation [1] state symbols [1] x 3
KCl(aq) + AgNO3(aq) à AgCl(s) + KNO3(aq)
KBr(aq) + AgNO3(aq) à AgBr(s) + KNO3(aq)
KI(aq) + AgNO3(aq) à AgI(s) + KNO3(aq)