Formulae, Equations, Moles Flashcards
How do halogens exist?
Halogens exist as diatomic molecules attracted to each other by weak intermolecular forces. A diatomic molecule contains two atoms covalently bonded together
What is the law of conservation of mass?
Atoms cannot be created or destroyed by chemical reactions. The same atoms are present at the start and at the end of a reaction
Why does mass seem to change during some reactions?
Substances can leave or enter the reaction mixture in a non-enclosed system. This usually happens in an open container where a product is a gas
Why does mass appear to go up in some reactions?
Metal product is exposed to air and reacts with the oxygen in the air. The metal atoms combine with oxygen atoms to form a metal oxide in solid state
What do balanced equations help to show?
How the atoms are rearranged in a reaction
The relative amounts of each substance involved
What are half equations?
A half equation is a model for the change that happens to one reactant in a chemical reaction
What is left in an ionic equation?
Molecular substances (Covalent bonds), Solids
What is a mole?
A mole is the unit for amount of substance. The mole is defined as the amount of any substance that contains the same number of entities as 12g of carbon-12.
How many entities are in a mole?
The number of entities in 1 mol is Avogadro’s constant. This is 6.02 * 10^23
What is the molar mass?
The mass of 1 mol of a substance is its relative atomic mass. This is the molar mass. The molar mass of carbon is 12.0 so it is 12g/mol
What is the mole equation?
Mol = Mass // Molar Mass
What is a limiting reactant?
One reactant is usually in limiting amount and so less of it is present than is needed to react with the other reactant. The amount of product formed is determined by the amount of the limiting reactant
