Combined Higher Flashcards
What is the Law of Conservation of mass?
In a chemical reaction, atoms are not created or destroyed, just rearranged.
Total mass before = Total mass after
When a metal forms a metal oxide, why does the mass increase?
one of the reactants is a gas - atoms of oxygen gas have bonded to the metal and can now be weighed.
When an acid reacts with a metal, why does the mass decrease?
a gas is produced and escapes
What is relative formula mass? (Mr or RMM)
the sum of the relative atomic masses of each atom in a substance
What are the four state symbols and what do they stand for?
(s) - solid, (l) - liquid, (g) - gas, (aq) - aqueous or dissolved in water
How can you tell when a symbol equation is balanced?
the number of atoms of each element is the same on both sides
What is a mole?
the mass of a substance that contains 6.02 x 1023 particles
Give the value for the Avogadro constant?
6.02 x 1023
Which formula is used to calculate the mass of a substance from number of moles and Mr?
mass = moles x Mr
Which formula is used to calculate the number of moles of a substance from mass and Mr?
moles = mass / Mr
What is a limiting reactant?
The reactant that is completely used up in a chemical reaction
What is a unit for concentration?
g/dm3 or mol/dm3
Which formula is used to calculate concentration from mass and volume?
concentration (g/dm3) = mass (g)/ volume (dm3)
Which formula is used to calculate volume from concentration and mass?
volume (dm3) = mass (g) / concentration (g/dm3)
Which formula is used to calculate mass from concentration and volume?
mass (g) = concentration (g/dm3) x volume (dm3)
