Which of these statements about the common-ion effect is most correct? a) The so
ID: 528539 • Letter: W
Question
Which of these statements about the common-ion effect is most correct? a) The solubility of a weak ionizing salt MA is decreased in a solution that already contains either M or A b) Common ions alter the equilibrium constant for the reaction of an ionic solid with water. c) The common-ion effect does not apply to unusual ions like SO^2_3. d) The solubility of a salt MA is affected equally by the addition of either A^- or a non-common ion. The accompanying diagram shows how entropy varies with temperature for a substance that is a gas at the highest temperature shown. (a) What process correspond to the entropy increases along the vertical lines labeled 1 and 2? (b) Why is the entropy change larger for 2 than that for 1? At 900 degree C titanium tetrachloride vapor reacts with molten magnesium metal to form solid titanium metal and molten magnesium chloride. (a) Write a balanced equation for this reaction. (b) What is being oxidized and what is being reduced? (c) Which substance is the reductant, and which is the oxidant?Explanation / Answer
3)
Most correct is a
b is wrong because common ions doesn’t alter equilibrium constant. Equilibrium constant depends only on temperature
c is wrong because common ion effect can apply to any ions
d is wrong because solubility of MA is not effected by adding common ions
Answer: a
4)
a) Both process corresponds to increasing entropy as arrow is pointed up in both the cases
b) Length of arrow determines the entropy change. Since length of arrow 2 is large, the entropy change is large for 2
5)
a)
TiCl3(g) + Mg (aq) —> Ti (s) + MgCl2 (aq)
Now lets balance it,
2TiCl3(g) + 3Mg (aq) —> 2Ti (s) + 3MgCl2 (aq)
b)
Mg is oxidised form 0 oxidation state in Mg to +2 in MgCl2
Ti is reduced from +3 oxidation state in TiCl3 to 0 in Ti
c)
Since Mg is oxidised, it is reducing other substance.
Mg will be reductant
Since Ti in TiCl3 is reduced, it is oxidising other.
So, TiCl3 is oxidant