Calculations in Chemistry - C4 Flashcards
What is the definition of relative formula mass
It is the average mass of the compound with 1/12 the mass of a carbon 12 atom
What is the definition of relative atomic mass
It is the mass of an atom to the mass of an atom of carbon 12
What is a mole
A mole of atoms is 6.02 x10 23 atoms
This is avogadros number
what is the equation for moles
moles = mass (g) / Mr
What is percetage yield
It is how much product is made in a chemical reaction
What is the theorectical yield of a reaction
It is the yield that would happen if the reaction was perfect
What is the equation for percentage yield
= actual yield/theorectical yield x100
What are the reasons for less than 100% yield
impure raw materials incomplete reaction competing reactions Miss weighing loss of product
What is the equation for atom economy
= Formula mass of product/Total formula mass of reactants x100
What is the atom economy of a reaction
It is the measure for how efficient the reaction is
What volume does a mole of gas take up at room temperature
24 dm3 = 24,000 cm3
What is the equation for moles of gas
= volume of gas (dm3) / 24
what is the equation for relative atomic mass
(Percentage x relative atomic mass) / 100
What is a titration
A method where a solution of a known concentration is used to determine the unknown concentration of a substance
What is the equation for moles
moles = concentration x volume
How does a titration work
Use the volume and concentration of one reactant to calculate the moles
Use the equation to find the moles of the other reactant
Calculate the volume or concentration as required of that reactant
