2Components of a Solution Solute: substance being dissolvedEx: Salt, SugarSolvent: substance doing the dissolvingEx: Water, Hexane
3What Dissolves in What? Solute must form attractions to the solvent. Polars dissolve polarsNonpolars dissolve nonpolarsPolar solvents dissolve most ionic crystals
4Solubility: How much solute can be dissolved in a volume of solvent undercertain conditions oftemp. and pressure.
5Using Reference Table G Shows solubility in grams of solute per 100 grams of water at different temperatures
6Saturated Solutions: hold max solute possible at that temp.Table G:Solubility curves show saturation levels atdifferent temps (in 100g of water).
7Saturated Solutions are at EQUILIBRIUM. Rate of dissolving = Rate of crystallization
8Go to 50 °C and up to NaNO3 and over. Ex: How many grams of NaNO3 are needed to create a sat. solution in 100g of water at 50 °C?Go to 50 °C and up to NaNO3 and over.Answer: 116 grams
9Look at The Water!! Table G is for 100 grams of water. Amount of water in your problem may be different and you need to adjust you answer.
10How many grams of NaNO3 are needed to create a sat. solution in 300g of water at 50 °C?Answer: 116 grams x 3 (three times as much water!)Or you can use a proportion:116 grams = x grams100 g H g H20
11Unsaturated Solutions: could still hold more solute at that temp.Would fall “below the line” on Table GEx: 40 g of NaNO3 in 100g water at 50°
12Supersaturated Solutions: hold more solute than they should at that temp.Would fall “above the line” on Table GEx: 140 g of NaNO3 in 100g water at 50°
13How do Supersaturated Solutions Form? Created a saturated solution at a high temp. and slowly let solution cool.Certain solutes can stay in solution (like sodium acetate).
14solutions are unstable. Add just one more “seed crystal” to the Supersaturatedsolutions are unstable.Add just one more“seed crystal” to thesolution, all the excesssolute will precipitateout quickly.Supersaturated Sodium Acetate solution after seed crystal added
15Describe These Solutions Saturated, Unsaturated or Supersaturated?100 g NH4Cl at 70° in 100 g water10 g SO2 at 10° in 100 g water40 g NaCl at 90° in 100 g water
16100 g NH4Cl at 70° in100 g waterFalls above the line (Supersaturated)
1710g SO2 at 10° in 100gwaterFalls below the line (Unsaturated)
1840g NaCl at 90° in 100gwaterFalls on the line (Saturated)
19Concentrated Solutions: have a lot of solutedissolved in the solventEx: Saturated solution of KIat 10°135 grams in 100 g water = pretty concentrated
20Dilute Solutions: only have a little solutedissolved.Ex: Sat. solution of SO2 at 50°4 grams in 100 g water = relatively dilute