C3 Flashcards
What is the law of conservation of mass?
No atoms are lost or made during a chemical reaction so the mass of the products = the mass of the reactants.
What charge do metals form as ions?
Positive ions
How to find the formula of ionic compounds?
Find the charges and make sure they cancel out.
Define relative atomic mass
Average mass of the isotopes of that element weighed to take into account the abundance of each isotope.
Define relative formula mass of a compound
The sum of the relative atomic masses of the atoms in the numbers shown in the formula (has no units).
How to calculate percentage by mass?
- Find the relative formula mass. 2. total RAM of the atoms of that element / Mr of the compound * 100
Define mole
An amount of a substance that contains the Avogradro number of particles - 6.02 * 10^23
How to find the number of moles?
Number of moles = Mass (g) / RAM (Ar) or RFM (Mr)
How to use moles to balance equations?
Find the moles of each substance (mass / Mr) and then find the lowest possible ratio by dividing all of them by the smallest number.
Calculate the number of moles of atoms in one mole of water molecules.
1 molecule of water contains 3 atoms so 1 mole of water molecules contains 3 moles of atoms.
Calculate the number of atoms in one mole of hydrogen chloride.
2 x 6.03 * 10^23 = 1.204 * 10^24 atoms.
How to calculate the number of atoms in a given mass of a substance?
Find the number of moles and then multiply that by number of atoms and then by Avogadro’s constant.
How to calculate the mass of a substance produced from a given mass on another substance and unlimited mass of another?
- Find the number of moles by dividing the given mass by the Mr. This is the same as the product. 2. Multiply the number of moles in the product by the Mr to find the mass.
Define limiting reactant
The reactant that is fully used up.
Define excess reactant
The reactant that is not fully used up.
