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2 How Substances Dissolve Solids dissolve in liquids at the surface Water molecules are moving  Polar molecules Positive and negative areas Solid molecules move  Polar molecules Same process for liquid with gas or melted solid with melted solid

3 Factors Affecting Reaction Rates Most reactions go faster at higher temperatures  Due to kinetic energy-hotter leads to faster particles  Faster particles lead to higher energy which leads to more collisions Example –potato slices cook faster at than 100 0

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5 Larger surface area speeds up reactions More exposed area the faster the reaction  Example – whole potato will take 30 minutes to cook  Same potato sliced will take 10 minutes  Solids-powder will dissolve quicker in solution than large block of material

6 Concentrated (stronger) solutions react faster Small amount of solution will not be effective  Bleach Large amount of solution will be effective

7 Reactions are quicker at higher pressure -Higher pressure - more particles in lead to more collisions  Quicker reactions -Lower pressure comes - less particles lead to less collisions -Slower reactions -Example – shake up a bottle of soda- increase collisions which increase explosion when opened

8 Massive, bulky molecules react slower The larger the molecule the slower it is Some molecules need to collide on particular side for reaction to happen  This takes many tries before large molecules react Result – compounds react very slowly

9 Catalysts Changes the rate of chemical reactions without being consumed Speeds up or slows down reactions Inhibitor-catalysts that slows reactions Solid catalyst- usually speeds up reactions  Catalytic converter on car  More effective with large surface

10 Equilibrium Systems The balance between a chemical reaction and its reverse occurring simultaneously  Carbonated drink in closed container  Burning, rusting and explosions are completed reactions Can’t be reversed

11 Some changes are reversible  Carbonated drinks have CO 2  When the can is opened bubbles go into air and some back into drink

12 La Chatelier’s prinicple of equilibrium A change in chemical equilibrium leads to an equilibrium shift to a new equilibrium  Change is caused by Temperature – Pressure – Concentration-