What I need to know about… Unit 4

Molarity Concentration of a solution Described in moles of solute per liter of solution Unit is M (said as molar) or mol/L Formula is M=n/V Can be used in a formula or in a conversion factor The higher the number, the more concentrated the solution

Dilution Adding more solvent Moles stay CONSTANT That’s why the M1V1= M2V2 works The solution being diluted is normally referred to as a stock solution

Solubility Ability to be dissolved Rules! Remember if a rule contradicts an earlier rule, the earlier rule wins Solubility curves- Tells how much solute can be dissolved in a particular volume of water (usually 100 mL) at a certain temp Generally increases with temp

Titrations Neutralization of acids and bases Must account for the amount of H+ and OH- All acid base reactions produce water and a salt (usually the salt is soluble) You can use the modified dilution formula (accounting for numbers of H/OH) or stoichiometry to solve this problems Titrations are used to find an unknown concentration and they use an indicator to show the endpoint

Redox Two reactions in one One species (element) is oxidized (loses e-) One species is reduced (gains e-) Rules for assigning oxidation numbers If there is no change in oxidation numbers, then the reaction is not redox Oxidizing and reducing agents must be reactants

General info on reactions When writing a chemical, complete ionic or net ionic reaction you MUST includes STATES OF MATTER If you are showing an ion it MUST have a CHARGE If you are using the reaction to complete any type of stoichiometry problem you must balance

Other vital information Like dissolves Like is the general rule of making a solution For example, polar substances will dissolve in polar solvents and vice versa Water’s polarity makes it a great solvent Strong electrolytes- break apart well/form lots of ions Weak electrolytes- form few ions Nonelectrolytes- form no ions

And by the way… You still must know your charges/polyatomics etc. You still have to be able to balance charges to form an ionic compound You still need to be able to find molar mass, convert from grams to moles, moles to grams, etc And you have to be able to use stoichiometry