1.2 amount of substance

Question 1

empirical formula definition

Answer 1

the simplest whole number ratio of atoms of each element in a substance

Question 2

molecular formula definition

Answer 2

the actual number of atoms of each element in a substance

Question 3

relative atomic mass formula

Answer 3

average mass of an atom/a twelfth the mass of 1 atom of carbon-12

Question 4

relative molecular/formula mass formula

Answer 4

average mass of a molecule/formula/a twelfth the mass of 1 atom of carbon-12

Question 5

why should small quantities of a solid not be used in a water of crystallisation experiment

Answer 5

the percentage uncertainties in weighing will be too high

Question 6

why should large quantities of a solid not be used in a water of crystallisation experiment

Answer 6

the decomposition will be incomplete

Question 7

why should the crucible be dry in a water of crystallisation experiment

Answer 7

the mass loss would be too large as the water would be lost when heating- it would give an inaccurate result

Question 8

why should the lid of the crucible be loose fitting in a water of crystallisation experiment

Answer 8

prevents loss of solid but allows gas to escape

Question 9

difference between relative molecular mass and relative formula mass

Answer 9

Relative molecular mass= sum of the atomic masses of the atoms in the molecule.
Relative formula mass= sum of the atomic masses of the atoms in the empirical formula

Question 10

% yield formula

Answer 10

actual yield/theoretic yield x100

Question 11

ideal gas equation

Answer 11

PV=nRT

Question 12

units for volume in ideal gas equation

Answer 12

m^3

Question 13

cm^3 to m^3

Answer 13

divide by 1,000,000
x10^-6

Question 14

cm^3 to dm^3

Answer 14

divide by 1,000
x10^-3

Question 15

how to find molecular formula from empirical formula

Answer 15

mr of MF/mr of EF