No atoms are created or destroyed during a chemical reaction. This allows calculations to be made on the quantities of substances that react and of the products made.
In a closed system, how does the total mass of the products of a reaction compare with the total mass of the reactants?
It is the same
It is greater
It is less
What is the relative formula mass of magnesium oxide, MgO? (Relative atomic masses: Mg = 24.3, O = 16.0)
What is the relative formula mass of MgCO3? (Relative atomic masses: Mg = 24.3, C = 12.0, O = 16.0)
What is the value of the Avogadro constant?
6.0 × 1023
6.0 × 10-23
2.3 × 106
The definition of the mole states that the number of particles in one mole of a substance are the same as in 12 g of what?
The element carbon
How many moles of atoms are there in 8.0 g of helium atoms? (Relative atomic mass: He = 4.0)
How many moles of molecules are there in 64.0 g of oxygen molecules, O2? (Relative atomic mass: O = 16.0)
Rearrange this equation to make mass the subject: number of moles = mass ÷ relative formula mass.
mass = moles × relative formula mass
mass = moles ÷ relative formula mass
mass = relative formula mass ÷ moles
If 92.0 g of Na reacts with 32.0 g of O2, what is the reacting ratio of Na:O2? (Relative masses: Na = 23.0 and O2 = 32.0)
Calcium carbonate decomposes when heated: CaCO3 → CaO + CO2. What mass of CaO can form from 100.1 g of CaCO3? (Relative formula masses: CaCO3 = 100.1, CaO = 56.1)