Solutions & Solubility Factors Affecting Solubility

A solution is the same thing as a homogeneous mixture (a mixture with the exact same composition throughout).

Parts of a Solution Solute-the substance that is being dissolved in a solution Solvent-the substance in a solution that is doing the dissolving

Parts of a Solution Example: In a saltwater solution (salt dissolved in water): Salt is the solute Water is the solvent

When two liquids are able to dissolve into each other, they are called miscible. ex) water & vinegar If not, they are called immiscible. ex) water & oil

Solubility is the amount of a substance that will dissolve into an amount of solvent at a given temperature

A solvent (like water, for example) can only hold so much of a solute. Or in other words, there is a maximum amount of solute that any solvent can hold.

Concentration-the amount of solute that is dissolved into a solvent Concentrated-when a solution has a high concentration of solute Dilute-when a solution has a low concentration of solute

Concentration can be described in terms of “weak” or “strong”, “concentrated” or “dilute”, but these are both relative terms and can be subjective.

A more objective way to describe concentration is molarity; we will discuss molarity in more detail later this year.

A saturated solution cannot hold any more of a solute at a given temperature. An unsaturated solution can hold more solute at a given temperature.

Sometimes, a solution can hold more of a solute than it should theoretically hold. This type of solution is called supersaturated. A supersaturated solution requires heating and stirring.

Supersaturated Solution Video

Summary: Types of Solutions: Unsaturated Saturated Super Saturated Solvent can hold more solute; not ‘full’ Solvent can not hold more solute; ‘full’ Solvent holds more solute than normal; ‘extra full’

‘Soup Can’ analogy: Think of the solvent as a can, and the solute as the soup. Unsaturated Saturated Super Saturated

In gases, pressure affects solubility In gases, pressure affects solubility. The higher the pressure, the more gas is soluble in a solvent. ex) carbonated drinks

Generally, a substance’s solubility increases as temperature is increased. Why? The solvent’s particles are moving faster and can dissolve more solute.

In gases, however, as the temperature increases, the solubility of the gas decreases. ex) power plants can kill fish because of the increased temperature of the water and reduced levels of oxygen

Effect of temperature on solubility (solubility chart)

Practice Problem #1 How many grams of KNO3 can 100 grams of water hold at 70 oC? 120 grams

Practice Problem #2 At what temperature can 100 grams of water hold 70 grams of KBr? 25 oC

Practice Problem #3 How many grams of NaNO3 can 75 grams of water hold at 55 oC? 105 grams of NaNO3 in 100 grams of water: 105 g/100 g = x /75 g X = (105x75)/100 X = 78.75 g NaNO3

Practice Problem #4 What type of solution results when you mix 45 g of NH4Cl in 100 g of water at 70 oC? Can hold 63 g; 45 g < 63 g; solution is unsaturated.

LMS/Chemistry/Lessons/Solubility Open and Save the 2 files titled: Solubility Worksheet w/ curve 1213 Solubility Worksheet 1213 Use the remaining class time to work on these 2 worksheets ELECTRONICALLY.