Solid and Gas Solubility

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Solid and Gas Solubility

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What is Solubility?

• Simply put, solubility is dissolving one thing
  into something else.
• Sugar in water, salt in water.
• Specifically, it is the maximum amount of solute
  that will dissolve in a certain amount of water.

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Solubility Details

• Remember, solute is what you are dissolving and
  solvent is what is doing the dissolving.
• The amount of solute is expressed in grams.
• The amount of solute dissolved is dependant on
  the temperature of the solvent.

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Lets say it again!

• If you change the temperature of the solvent, the
  amount of solute that will dissolve will also
  change.
• If you change the amount of solvent, the amount
  of solute that will dissolve will change.

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How long does it take?

• Many factors affect the amount of time it takes
  for a solute to dissolve.

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How long does it take to dissolve?

• How soluble the solute is.
• How big the crystals are.
• How much you stir.
• How long you stir the solution.

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How long does it take to dissolve?

• These factors do not affect the total amount of
  solute that will dissolve, only the time it takes
  to dissolve.
• For example, stirring rapidly and for an extended
  time period does not change how much sugar you
  can dissolve in Kool-aid, only how long it takes
  for the sugar to dissolve.

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A Specific Amount

• Because there are specific amounts of solutes
  that can be dissolved in solvents, there are 3
  definitions that we can now use to describe
  solutions.
• Unsaturated
• Saturated
• Supersaturated

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Unsaturated Solutions

• If a solution is unsaturated, then the solvent
  can dissolve more solute at that temperature.

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Saturated Solutions

• If a solution is saturated, then it has dissolved
  the exact amount it can at that given temperature.

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Supersaturated Solutions

• If a solution is supersaturated, then it is has
  dissolved more solute than a saturated solution
  has.
• This is difficult to achieve.
• Usually requires heating and then slowly cooling
  the solution.
• Will eventually release some dissolved solute to
  return to a saturated state.

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How can we tell the kind of solution?

• In order to know when our solutions are saturated
  or not, we have to know the solubility of the
  solute.
• To do this, we look at a solubility curve.

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Solubility Curves

• A solubility curve graphs the temperature of the
  solvent versus the grams of solute dissolved in a
  given amount of solvent.
• This curve shows the solubility for a range of
  temperatures.

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Solubility Curves

• In addition to showing us saturated solutions,
  they also can be used to determine if a solution
  is supersaturated and unsaturated.

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Solubility Curve Example
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An Unsaturated Solution
A point here would be unsaturated
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A Saturated Solution
A point here would be saturated
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A Supersaturated Solution
A point here would be supersaturated
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Solid and Gas Solubility

• The 3 phases of matter all behave differently
  with solubility.
• We will discuss how solids and gases differ in
  solubility.

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Solid Solubility

• By studying solubility graphs, a general trend
  can be seen.
• As you increase temperature, the solubility also
  increases.
• At higher temps, you can dissolve more.

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Solid Solubility

• A positive slope on the curve indicates this
  trend.
• Every compound has a distinct solubility thus
  making this a physical property.

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Gas Solubility

• As with solids, temperature affects the
  solubility of gases.
• But, the trend is opposite, as you increase the
  temperature, the solubility decreases.

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Gas Solubility

• In addition to temperature affecting gas
  solubility, gas pressure also determines the
  solubility of a gas.
• Gas solubility is directly proportional to the
  gas pressure.
• The higher pressure, the more gas that will
  dissolve.

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A Good Example

• Carbonated beverages contain dissolved CO2.
• When you open a can of soda, the pressure is
  decreased and the amount of CO2 dissolved also
  decreases. Thats why you see bubbles coming up.

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Solution Concentration