Factors that Affect Solubility

If dissolving occurs only when the solute and solvent particles come in contact with each other, via collisions, What factors can we manipulate to change how

often these solute and solvent particles collide in order to increase the rate or speed at which the SOLUTE dissolves in the solvent (a.k.a. Solubility)?

Solubility is the quantity of solute that dissolves in a given amount of solvent. The solubility of a solute depends on the nature of the

solute and solvent, the amount of solute, the temperature and pressure (for a gas) of the solvent.

Solubility is expressed as the amount of solute per 100 g of solvent at a specific temperature.

Some solutions form quickly and others form slowly. The rate depends upon

3 factors

Stirring (Agitation) The size of solute (surface area)

Breaking a solute down into small pieces increases the surface area

Greater surface area allows for more points of contact between solvent and solute particle which will increase the rate at which the solute dissolves(solubility)

Heating (Temperature) Increasing the temperature of a solvent (except gases)

will increase the rate at which the solute dissolves (solubility)

Solubility of Three Unknown Compounds

-Copy this table down in your NB-TEMPERATURE Compound A-

IonicCompound B- Gas

Compound C-Ionic

0°C 13g/L 200 g/L 40 g/L

20°C 32 g/L 125 g/L 45 g/L

40°C 110 g/L 75 g/L 50 g/L

60°C 246 g/L 0 g/L 55 g/L

20 °C 60 °C40 °CTemperature

20 °C 60 °C40 °CTemperature

Using the table and graph at your table… What do the unsaturated “points” on the table have

in common with the graph?- where do those points fall on the graph compared to the “line/solubility curve” drawn for the substance you are looking at? (on the line, above the line, below the line?) Look at least 3 “points” for unsaturated, saturated, and

supersaturated. Do you see a pattern?

When you’ve got the pattern come up and get a baggy of agree or disagree practice cards

Interpreting the graph1. Name the variable and unit found on the X axis: _________

2. Name the variable and unit found on the Y axis: _________

3. Each curve shows how solubility for each compound changes as ___________ changes

4. The solubilities of the compounds whose curves show GREATER slopes are (more or less?) affected by changes in temperature

Exit ticket- write you group names on the notecard and Answer #1 and #2 1) What is the maximum amount (in grams) of

NaNO3 that will dissolve at 25 degrees Celsius? 2) at 40 degrees Celsius, I have added 110 grams of

NaNO3 to my solvent. a) Do I have an unsaturated, saturated, or supersaturated

solution?

b) I cool my NaNO3 solution from 40 degrees to 20 degrees. I now I have a saturated solution and my solution now has crystals at the bottom of it. I filtered out the crystals and weigh them. Calculate the amount, in grams, of NaNO3 that crystallized out of solution. (remember I started with 110 grams of solute)

Answers to exit ticket

1) 90 grams of solute

2) a. Supersaturated

b. 25 grams of NaNO3 crystals (at 40 degrees we had 110, at 20 degrees we want to use how many grams of solute it will take to make a saturated solution= 85 grams at 20 degrees. Therefore, the difference from 110-85=25 grams that will crystallize leaving the other 85 grams, the max amount of NaNO3 that will dissolve in solution at 20 degrees (definition saturated if it doesn’t click)