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How Substances Dissolve

Solids dissolve in liquids at the surfaceWater 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

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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 2000 than 1000

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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

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Concentrated (stronger) solutions react faster

Small amount of solution will not be effective Bleach

Large amount of solution will be effective

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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

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Massive, bulky molecules react slower

The larger the molecule the slower it isSome molecules need to collide on

particular side for reaction to happen This takes many tries before large molecules

react Result – compounds react very slowly

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Catalysts

Changes the rate of chemical reactions without being consumed

Speeds up or slows down reactionsInhibitor-catalysts that slows reactionsSolid catalyst- usually speeds up reactions

Catalytic converter on car More effective with large surface

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Equilibrium Systems

The balance between a chemical reaction and its reverse occurring simultaneously Carbonated drink in closed container Burning, rusting and explosions are completed

reactionsCan’t be reversed

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Some changes are reversible Carbonated drinks have CO2

When the can is opened bubbles go into air and some back into drink

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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-