Chemistry 4 Flashcards
When does a chemical reaction occur
when two or more chemicals are combined to form a new substance (chemical change)
Define reactants
materials that are combined to start a reaction
Define products
new materials produced by the reaction
Give an example of a chemical reaction written as a word equations
wood + oxygen ——-> Carbon dioxide + water + energy
Indicators of chemical change
-color change
-change in odor
-formation of a solid (precipitate)
-formation of a gas (bubbling)
-release or absorption of energy (turning hot or cold)
Define exothermic reactions
release energy to the surroundings. (heat ‘exits’)
Define endothermic
reactions absorb energy from their surroundings. (heat ‘enters’)
Define combustion
oxygen reacts with a chemical to produce a new substance and a release of energy
Define corrosion
when oxygen in the air reacts with a metal, such as the rusting of iron.
Define cellular respiration
It is the reaction of oxygen with glucose from food to produce water, carbon dioxide and energy.
What is the Law of Conservation of Mass
In any chemical reaction, the total mass of the reactants is equal to the total mass of the products. Matter is neither created nor destroyed.
Define catalyst
A catalyst helps a reaction proceed more quickly. (ex. enzymes)
What things can affect the rate of reaction
Concentration- With more reactants, a reaction proceeds more quickly
Temperature- The atoms heat up and move faster
Surface Area- if the surface area of a reactant is increased, reaction rate speeds up because more of the reactant is available to react.
