Solubility & Concentration

Question 1

Concentration

Answer 1

• Chemists are interested in quantifying how much solute is dissolved in solvent
• This is done through a ratio, called concentration
• Ratio: Quantity of solute to the quality of solution/solvent
  *

Question 2

Low and high concentrations

Answer 2

• High concentration/Concentrated solution= Large number of solute particles compared to solvent
• Low concentration/DIlute solution= Little solute particles in solution/solvent

Question 3

Amount Concentration

Answer 3

• Solution concentrations are expressed in amount (in moles) of solute per litre of solution
• c= n/v

Question 4

Saturated solution

Answer 4

• A solution that has the maximum amount of solute
• There is a limit to how much solute you can dissolve in a solvent
• Solubility: The maximum concentration of a compound in a solvent (typically water) or The maximum possible concentration of a solute at specific temperature and pressure

Question 5

Degrees of saturation

Answer 5

• Unsaturated solution: A solution that contains less than the maximum quantity of solute
• Supersaturated solution: Solutions can be forced to dissolve more solute than it normally could under special circumstances

Question 6

Solubility curve

Answer 6

• A graph of solubility based on the given solute against temperature
• The curve represents saturated solution we want to create
  If data point is below curve, it is unsaturated and there is not enough solute particles in solution
  If data point is above curve is a supersaturated solution

Question 7

Solubility curve of solids

Answer 7

• Typically with solids, as temperature increases, more energy and collisions are made, leading to more products being made.
• This increases solubility

Question 8

Solubility curve of gasses

Answer 8

• As temperature increases, the solubility of gasses decreases
• When a particle is given energy, it changes states.
• As temperature of gas increases, it does not want to be soluble, it wants to leave state and go into gas phase (out of solution → gas)

Question 9

Creating a supersaturated solution

Answer 9

• Solute is dissolved at a high temperature, and then the solution is cooled
• When the temperature drops, the solubility drops, but the extra solute does not crystallize from the solution immediately
• The solution becomes supersaturated

Question 10

crylizing extra solute from supersatured solution

Answer 10

• The extra solute stays dissolved until something disturbs the system
• Tap on flask or dropping a single crystal of solute into the solution can create crystallization
• This creates movement in the solution The “seed crystal” provides a surface for extra solute to crystallize

Question 11

Pressure

Answer 11

• Gases are mainly impacted by changes in pressure (but not for liquids and solids)
• Solubility of a gas in a liquid increases as the pressure of gas is increased
• Forcing the gas into the solution

Question 12

Pressure and tempertures in gasses

Answer 12

• Low temperatures have less energy to escape out of liquid phase (higher solubility)
• Higher temperatures have more energy to escape out of liquid phase (less solubility)

Question 13

Soft drinks and pressure

Answer 13

• When soft drinks are closed, the carbon dioxide is under high pressure above the solvent and keeps the CO2 molecules dissolved in solution
• When the drink is opened, pressure is released and bubbles rise to the top. The pressure drops which allows CO2 to come out of the solution, making it less soluble (creating fizzing/bubbles)