Introduction to Solutions Unit 8 lecture 1 Introduction to Solutions

What is a solution? Homogenous mixture (same throughout) of two or more substances “Like dissolves like” (polar in polar, non-polar in non-polar) Solute (what there is LESS of) dissolves in the solvent (what there is MORE of)

What goes on to make a solution? Random motion of molecules Attraction of solute to solvent is greater than its attraction to itself Physical reaction (breaking of intermolecular forces)

Qualitative solutions Dilute versus concentrated Dilute- small amount of solute per solvent Concentrated- large amount of solute per solvent

Saturation level Unsaturated- the solution has only a small amount of solute (can hold more) Saturated- the solution has as much solute as it can hold (at a certain temperature/pressure) There will be solute at the bottom Supersaturated- the solution is “tricked” into holding more solute than can normally be dissolved (this is done by heating, dissolving, then cooling)

Only 91 g of the solute can be dissolved in the solvent water at 250C

Solubility curves- show how much solute can be dissolved in a solvent at certain temperatures How many grams of KNO3 are dissolved in 100g of water at 600C? How many grams of NH3 are dissolved in 200g of water at 100C?

3. Which of the solutes varies INVERSELY with temperature? 4. If you had a KCl solution at 700C and then cooled it to 200C how many grams of solute would come out of solution? 5. How many grams of NaNO3 can be dissolved in 50g of water at 100C? 6. If you had 40 grams of NH3 in 100g of water at 100C, would it be saturated, unsaturated or supersaturated?