Solution A solution is a homogenious mixture of a substance mixed in a second substance. An alloy is a solution of metals evenly mixed together, an example is Brass Air is a soltution of evenly mixed gasses

We will be dealing primarily with liqued solutions. Terms: The solute is the thing that is being dissolved The solvent is the thing doing the dissolving

Examples If salt is added to water The salt is the solute The water is the solvent

solubility Different things have different solubility Sugar & salt dissolves (Soluble) The metal spoon & oil dont (insoluble)

Why do things dissolve If a molecule is polar or ionic (has a charge) it will be attracted to the charges in water. The charges of the water will ‘latch onto’ the charges of the solute and dissolve it

Why do things not dissolve If something has no charge (non polar) it wont be attracted to the water. This will make is insoluble.

Fats Oil, fats, grease etc. are all non polar, they have no charges for the water to ‘latch onto’ to dissolve them Soap has 2 sides, 1 polar 1 not polar. The non polar side can dissolve the grease, and the polar side can dissolve in water.

Factors that affect solubility Think about a warm soda… What happens to the solubility of gasses in warm and cold water? What happens to the solubility of sugar in hot or cold water?

Temperature As temperature increases more solid can be dissolved. As temperature increases less gas can be dissolved.

Pressure When you open up a bottle of soda the CO2 gas rushes out… What does this tell us about the effect of pressure on the solubility of gas?

Pressure As pressure decreases the solubility of gasses decrease. This is why as the bottle is open (and pressure goes down) gas rushes out of the soda. But it tastes just as sweet. Pressure doesn’t affect solubility of solids

Table G Table G on your reference table tells you the solubility of various compounds in different temperature water.

Concentration If we dissolve a lot of sugar in water we may say its concentrated. Or if we dissolve a little sugar we may say its dilute. But these terms are imprecise

Molarity Molarity is how we measure the concentration of a solution. It means moles of solute (sugar) per liter of solvent (water) Molarity = moles solute/liters solvent

Example What is the molarity of a solution that has 4 moles of NaOH in.5L of solution? What is the molarity of a solution that has 12 moles of HCl in 6 liters of solution?

Example A can of soda has.21 moles of sugar in.35 Liters A carton of apple juice has.07 moles of sugar in.12 Liters Find the molarity for each

What is molarity of a solution that has 82.0 grams of Ca(NO 3 ) 2 in 2 liters

Parts per million Molarity measures the concentration of a solute when there is a lot of it. But what it we have a tiny amount of a solute.

Parts per million PPM (parts per million) is used to measure the concentration of tiny amounts. For instance a pool has 2 grams of chlorine per 1,000,000 grams of water

PPM The formula for PPM is found on the refernece table Ppm = grams solute/ grams solution then times 1,000,000 then times 1,000,000

Example If.0972 grams of carbon dioxide can be dissolved in 100 grams of water what is the ppm concentration?

Precipitates When 2 liquids are reacted they can sometimes react to form a solid that is un-dissolvable. This solid is called a precipitate.

Table F Table F Lists chemicals that can be dissolved, or form precipitates. Example does Li 3 (PO 4 ) dissolve in water? What about Al(PO 4 )

Colligative properties When a substance is dissolved in water, it spreads the water molecules out further. This makes it harder for them to clump together and lowers the freezing point.

If something is dissolved in water you also need to break to connections between the solute and water before it can evaporate. So a solute raises the boiling point

Recap Adding a solute to a solution Lowers the freezing point Raises the boiling point The more solute you add the greater the effect

Vapor pressure Even though a substance is in the liquid phase some molecules have enough energy to escape their neighboring molecules and enter the gas phase.

Vapor pressure These gas particles exert preasure on the air around them, As the temperature goes up, more molecules evaporate and the vapor pressure increases

Table H Table H, tells us the vapor pressure that a chemical exerts as the temperature is changed When the vapor pressure of a substance reaches the same pressure of the surrounding air it will boil (turn to gas).

Vapor Pressure Something boils when its vapor pressure equals the surrounding air pressure SO If the pressure of the surrounding air changes then the boiling point will change