Chemical Interactions Chapter 2

What are the things that are necessary to start and maintain a fire?

Fuel, oxygen, and heat

how can you become well prepared to take action for a fire?

knowing how to prevent and know what to do if a fire starts.

combustion

rapid reaction between oxygen and a substance called fuel

fuel

a material that releases energy when it burns

activation energy

the minimum amount of energy needed to a start a chemical reaction

what do chemical reactions need to get started?

a certain amount of activation energy

How do chemists control rates of reactions?

by changing factor such as surface area, temperature, and concentration, and by using substances called catalyst and inhibitors.

concentration

amount of a substance in a given volume

catalyst

material that increases the rate of a reaction by lowering the activation energy

enzymes

cells in your body (as in all living things) contain biological catalysts

inhibitor

material used to decrease the rate of a reaction

chemical equation

a short, easy way to show a chemical reactions, using symbols instead of words

What do chemical equations use?

Chemical formulas and other symbols instead of words to summarize a reaction.

reactant

substances you have at the beginning are called the reactants

products

reaction is complete you have new substances

conservation of mass

states that during a chemical reactions matter is not created of destroyed

What does the conservation of mass state?

that in a chemical reactions the total mass of the reactants must equal the total mass of the products

open system

matter can enter from or escape to the surrounding

closed system

matter is not allowed to enter or leave

How do you describe a chemical equation accurately?

it must show the same number of each type of atom on both sides of the equation

How can chemical reactions be classified?

synthesis, decomposition, replacement

synthesis

when two or more elements or compounds combine to make a more complex substance

decomposition

breaks down compounds into simpler products

replacement

when one element replaces another in a compound or when two elements in different compounds trade places

coefficient

a number placed in front of a chemical formula in an equation

matter

anything that has mass and takes up space

chemistry

the study of matter and how matter changes

How can matter be described in two kinds of properties?

physical properties and chemical properties

How can changes in matter be described?

in terms of physical changes and chemical changes

physical property

a characteristic of a substance that can be observed without changing the substance into another substance

chemical property

a characteristic of a substance that describes its ability to change into other substances. to observe the chemical properties of a substance, you must change it to another substance.

physical change

any change that alters the form or appearance of a substance but that does not make the substance into another substance

chemical reactions

a change in matter that produces one or more new substances

what is another name for chemical reaction?

chemical change

when do chemical changes occur?

when bonds break and new bonds form

what are the chemical reactions that involve two main kinds of changes that you can observe?

formation of new substances and changes in energy

precipitate

a solid that forms from the solution during a chemical reaction

endothermic reaction

reaction in which energy is absorbed

exothermic reaction

a reactions that releases energy in the form of heat