chemical reactions Flashcards
what is a chemical reaction?
two or more chemicals
what is a stubstance
a particular kind of matter with uniform properties.
what are productas
A substance formed in a chemical reaction.
what are reactants
Substances present at the start of a chemical reaction.
what are bonds
The chemical link that holds molecules together.
what is a word equation
An equation in which only the names of the reactants and products are used to model a reaction
what is a balanced equation
An equation in which the symbols and formulae of the reactants and products are used to model a reaction. Also called a symbol equation, balanced symbol equation or chemical equation.
how do you write a balanced equasion
replace the name of each substance with its symbol or formula
use numbers to balance the equation, if it is not already balanced
what does combustion mean
The process of burning by heat.
what does exothermic mean
Reaction in which energy is given out to the surroundings
what does endothermic mean
Reaction in which energy is taken in from the surroundings. The surroundings then have less energy than they started with, so the temperature falls
what does fuel mean
Material that is used to produce heat, like coal, oil or gas
what does hydrocarbon mean
A compound that contains hydrogen and carbon only
what is a bace
A substance that reacts with an acid to neutralise it and produce a salt
what does complete combustion mean
Burning in a plentiful supply of oxygen or air. Complete combustion of a hydrocarbon produces water vapour and carbon dioxide
what does incomplete combustion mean
Burning when there is a limited supply of air or oxygen
what does oxidation mean
The gain of oxygen, or loss of electrons, by a substance during a chemical reaction
what is acid
a substance with particular chemical properties including turning litmus red, neutralizing alkalis, and dissolving some metals; typically, a corrosive or sour-tasting liquid of this kind.
what does neutralise mean
To be made neutral by removing any acidic or alkaline nature
what does alkaline mean
Having a pH greater than 7
what does acidic mean
Having a pH less than 7
what does thermal decomposition mean
Type of reaction in which a compound breaks down to form two or more substances when it is heated
what does catalyst mean
Changes the rate of a chemical reaction without being changed by the reaction itself
what does balanced equation mean
An equation in which the symbols and formulae of the reactants and products are used to model a reaction. Also called a symbol equation, balanced symbol equation or chemical equation.
