Chemical Reactions

Indicators of Chemical Change

• sound produced

• change in colour

• gas being produced

Reactants

the substances that undergo change in a chemical reaction

Products

the substances formed in a chemical reaction

During a chemical reaction, the atoms are _______ to make new _______.

rearranged substances

To identify the Reactants:

look at what substances are being mixed/heating/or reacting

To identify the products:

look for evidence of a chemical change

Writing a chemical equation in the correct order: reactants on the ____, products on the ______, arrow meaning _______, and separate reactants/products with a ____ sign.

left right produces plus

Example of a Chemical Equation

magnesium + hydrochloric acid (arrow) magnesium chloride + hydrogen

Atoms are not destroyed, they simply rearrange

True

Law of Conservation of Mass

states mass cannot be created or destroyed

Closed System

a system in which matter cannot enter or leave (e.g a sealed container)

Superscript

the charge of an atom

Subscript

how much of each atom you have (cannot be changed)

Coefficient

how many atoms you have (can be changed)

Rate of Reaction

a measure of how fast the reactants turn into products

Collision Theory

the idea that particles need to collide to react

Changing the Temperature Rate of Reaction

+heat means particles are more likely to collide, -heat means they are less likely to collide

Changing the Concentration Rate of Reaction

increase the concentration particles are more likely to collide, decrease the concentration particles are less likely to collide

Change the Surface Area Rate of Reaction

larger total surface area means more particles are likely to collide, smaller total surface area means less particles are likely to collide

Catalyst

a substance that is added to a reaction to speed it up without chemically changing the reaction

Exothermic Reactions

reactions that release heat energy into the surroundings, happens when the energy in the reactant bonds is more than in the product bonds

Endothermic Reaction

reactions that absorb heat from the surroundings, happens when the energy in the bonds of the products is more than the bonds of the reactants