Amount of Substance

What is the formula for Hydrogencarbonate ?

HCO₃^-

What is the formula for Phosphoric acid ?

H₃PO₄

What is the relative atomic mass ?

The average mass of one atom of an element compared to 1/12 the mass of one atom of carbon-12

What does the relative atomic mass tell us ?

How much heavier or lighter an atom is compared to carbon

What is the relative molecular mass ?

The average mass of one molecule of an element or compound compared to 1/12 the mass of carbon-12

What is the relative formula mass ?

The average mass of the elements in a compound compared to the mass of 1/12 of carbon-12

What is the empirical formula ?

The simplest whole number ratio of atoms of each element in a compound

What is the molecular formula ?

Actual number of atoms of each element in a compound

Why is the yield of a reaction never 100% ?

• The reaction may be reversible

• Some of the product may be lost when it is separated from the reaction mixture

• Some of the reactants may react in other reactions

How do you calculate the % yield of a reaction ?

(mass of product obtained / maximum theoretical mass of product) x 100

How do you calculate the % atom economy of a reaction ?

(mass of desired product / total mass of products) x100

How do you convert mol/dm³ to g/dm³ ?

Multiply by the Mr

How do you calculate concentration ?

moles / volume

What does heating to constant mass involve ?

• Heating the same reaction for several minutes

• Weighing it

• Repeating this until 2 consecutive mass measurements are the same

What is the purpose of heating to constant mass ?

Ensures all of the water of crystallisation is removed

How do you calculate pressure ?

(moles x gas constant x temperature) / volume

How do you convert m³ to dm³ ?

x1000

How do you convert m³ to cm³ ?

x1,000,000

How do you convert kPa to Pa ?

x1000

How do you convert MPa to Pa ?

x10⁶

How do you convert degrees Celsius to kelvin ?

+273