T2W2L2: halides & precipitates & solubility

halides §

• halide ions are formed from the group VII elements, the halogens. Halides are detected using silver nitrate solution
  • Cl -, Br -, I -
  • colourless ions in solution.
• HCl + AgNO3 -> AgCl + HNO3
  • white precipitate
• HBr + AgNO3 -> AgBr + HNO3
  • cream precipitate
• HI + AgNO3 -> AgI + HNO3
  • yellow precipitate
• write ionic equations for those 3:
  • $C{l}^{-1}+A{g}^{+}=AgCl$
  • $B{r}^{1-}+A{g}^{+}=AgBr$
  • $I^{-1}+A{g}^{+}=AgI$

isolating the precipitates §

• precipitate from a reaction can be separated from the mixture by filtration.

solubility §

concentration of solubility in solution §

• a saturated solution is one in which no more solute will dissolve at a given temperature.
• an unsaturated solution contains less solute than needed to make a saturated solution. Most solutions we use will be unsaturated.
• a supersaturated solution is an unstable solution, usually formed as a saturated solution cools down. If it is disturbed, it will crystallise, forming crystals of solute, and leaving a saturated solution.
• the mass of substance that will dissolve in 100 g of water at 25 deg celsius (we don t measure amount of substances) is the definition of so/lubility
• if the solubility of sodium chloride is 36g/100g water. gram/litre of solubility

  chloride	volume of water (mL)	mass of chloride that dissolved (g)	g/L
  $CuC{l}_2$	200	151	755
  $MgC{l}_2$	150	80	533.3
  $KCl$	100	30	300
  $NaCl$	200	72	360
  $ZnC{l}_2$	150	618	4120
  order of solubility
  ZnCl2 > CuCl2 > MgCl2 > NaCl > KCl

32g of potassium chloride out of 75mL of water at 50 degrees.

supersaturated crystallisation §

when solutions contain more solute than they would normally be able to dissolve, solutions are called supersaturated crystallisation blah blah blahb ablah