amount of substance

Question 1

What is the definition of relative atomic mass?

Answer 1

The average mass of an atom of an element relative to 1/12th the mass of a 12C atom.

Question 2

What is the definition of relative formula mass?

Answer 2

1. The average of a molecule of a substance relative to 1/12th the mass of a 12C atom.
2. The sum of the relative atomic masses of all the atoms in the formula of a substances.

Question 3

What is the avagadro constant?

Answer 3

The number of particles in a mole.

Question 4

How to calculate moles using avo?

Answer 4

moles = mass/avo

Question 5

What is the ideal gas equation?

Answer 5

PV = nRT

Question 6

What units are used in the ideal gas equation?

Answer 6

Pressure = Pa
Volume = m3
number of moles = mols
gas constant = 8.31Jmol-1K-1
Temperature = K (°C + 273)

Question 7

What is the empirical formula?

Answer 7

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

Question 8

What is the molecular formula?

Answer 8

The actual number of atoms of each element in a compound.

Question 9

What are the common ionic equations?

Answer 9

acid + hydroxide
H+ (aq) + OH- (aq) –> H2O (l)

acid + carbonate
2H+ (aq) + CO32- (aq) –>H2O (l) + CO2 (g)

acid + hydrogencarbonate
H+ (aq) + HCO3- (aq) –> H20 (l) + CO2 (g)

acid + ammonia
H+ (aq) + NH3 (aq) –> NH4+ (aq)

Question 10

What is the % yield equation?

Answer 10

% yield = mass of product obtained/ ,maximum theoretical mass of product

Question 11

What is the % atom economy equation?

Answer 11

% atom economy = mass of desired product/ total mass of products