3.2 Determination of formula

Question 1

what is the molecular formula

Answer 1

actual number of atoms

Question 2

what is the empirical formula

Answer 2

simplest whole number ratio of atoms

Question 3

empirical formula of H2O

Answer 3

H2O

Question 4

empirical formula of C6H12O6

Answer 4

CH20

Question 5

define molecular mass

Answer 5

mass of a molecule relative to 1/12 the mass of a carbon 12 atom

Question 6

how is relative molecular mass calculated

Answer 6

adding together the relative atomic mass of the element making up the molecule

Question 7

what is the relative molecular mass of CH4

Answer 7

16

Question 8

what does relative molecular mass apply to

Answer 8

covalently bonded and discrete particles

Question 9

what does relative formula mass apply to

Answer 9

giant structures

Question 10

define relative formula mass

Answer 10

it’s the mass of a formula unit relative to 1/12 the mass of an atom of carbon 12

Question 11

calculate the relative formula mass of Ca(NO3)2

Answer 11

164.1

Question 12

calculate the empirical formula:

a compound contained 23.7% of C 72.7% of O

Answer 12

CO2

Question 13

find the empirical formula of 29.1% Na , 40.5% S, 30.4% O

Answer 13

Na2S2O3

Question 14

what is the equation for molecular formula

Answer 14

molecular formula = (molar mass/empirical mass) x empirical formula

Question 15

Calculate the molecular formula for CH2 with a molar mass of 56gmol-1

Answer 15

C4H8

Question 16

what is an ionic compound

Answer 16

metal + non-metal

Question 17

how do we know when all of the water is removed

Answer 17

we keep to a constant mass, heat them away repeatedly until the mass no longer changes, but don’t heat it to fiercely or the salt may decompose