Precipitation chem

Question 1

define saturated

Answer 1

max amount of solute dissolved in presence of XS solute

Question 2

define the solubility of a substance

Answer 2

= max amount that will dissolve in a given volume of solvent

Question 3

solubility depends on

Answer 3

chemical nature of the solute and solvent 
the temperature (generally higher solubility at higher temp)

Question 4

insoluble ionic solids generally have…

Answer 4

highly charged anions and cations, so that the attractive forces between anion/cations are greater than with water.

Question 5

Solubility rules - the soluble

Answer 5

ammonium, G1, nitrate and ethanoate salts

sulfates EXCEPT Ca, Sr, Ba, Pb

halide salts EXCEPT Ag+ and Pb2+

generally, anion charges -1 tend to be soluble

Question 6

solubility rules - the insoluble

Answer 6

OH- and O2-, except for Na+ and K+

Sulfides (S2-), Carbonates, Phosphates EXCEPT Na+, K+ and NH4+

in general, anion charge -2 or -3 insoluble.

Question 7

ions exist in solution as _____

Answer 7

hydrates

Question 8

what are hydrates

Answer 8

complexes of ions w/ H2O
written M+(aq) or X-(aq)

ion surrounded by H2O molecules, orientation depends on charge on ion.
H end is ∂+, O end is ∂-

Question 9

Cu2+ colour in solution

Answer 9

blue

Question 10

Fe2+ colour in sln

Answer 10

light green

Question 11

Ag+ in solution and ppt

Answer 11

cls sln, brown ppt Ag2O

Question 12

Fe3+ in sln and ppt

Answer 12

pale yellow sln

Fe(OH)3 red-orange ppt

Question 13

Mg(OH)2 solubility in XS NaOH and NH3

Answer 13

not soluble in either

Question 14

Ba(OH)2 solubility in XS NaOH and NH3

Answer 14

not soluble in either

Question 15

ions that form cls sln and white ppt w/ OH-

Answer 15

Mg2+, Ba2+, Pb2+, Al3+, Zn2+

Question 16

Pb(OH)2 solubility in XS NaOH and NH3

Answer 16

soluble in XS NaOH

NOT soluble in XS NH3

Question 17

Al(OH)3 solubility in XS NaOH and NH3

Answer 17

soluble in XS NaOH

NOT soluble in XS NH3

Question 18

Zn(OH)2 solubility in XS NaOH and NH3

Answer 18

soluble in both

Question 19

Add H2SO4 to find the difference between these two pairs of substances

Answer 19

Mg(OH)2 and Ba(OH)2
Both are not soluble in NaOH/NH3

Pb(OH)2 and Al(OH)3
Both are soluble in NaOH but not NH3

Ba and Pb form insoluble sulphates

Question 20

testing for CO3^2- and OH-

Answer 20

litmus

red–>blue in CO3^2- and OH-

add aq acid - carbonate reacts, forming H2CO3 which decomposes to H2 and CO2 (bubbles)

Question 21

testing for SO4^2-

Answer 21

add acidified BaCl

white ppt, BaSO4

Question 22

testing for Cl-, Br-, I-

Answer 22

add aq AgNO3

insoluble ppt formed
AgCl = white
AgI = cream/yellow

Question 23

differentiate Cl- and I- ions

Answer 23

first add aq AgNO3 to form AgCl and AgI

AgCl dissolves on addition of aq NH3 –> Ag(NH3)2^+
AgI remains undissolved

Question 24

define ligand

Answer 24

the groups in a complex ion that are bonded to the central ion

cation central, a long e- pair on ligand used for bonding

for H2O, nonbonding pair on O

Question 25

examples of possible ligands

Answer 25

molecules: H2O, NH3
anions: OH-, Cl-, SCN-

Question 26

what affects the numbers of attached ligands

Answer 26

the size and charge of the central ion

2, 4 and 6 are common

Question 27

formation of a complex ion results in

Answer 27

the precipitate dissolving

compound containing complex ion is soluble in water

Question 28

what ions have coloured ppts or complex ions?

Answer 28

transition metals