Equations and calculations

Question 1

Empricial forumla: which number to use from periodic table?

Answer 1

top number

Question 2

2 methods/experiments for finding empirical forumulae of compounds

Answer 2

Combustion
Reduction

Question 3

water of crystallisation is the water in a salt lattice

steps to calculate how much water of crystallisation a salt contains (after experiment)

Answer 3

1. moles of water lost
2. moles of anhydrous salt
3. ratio of anhydrous salt moles to water moles
4. round to a whole number

Question 4

Concentration formula

Answer 4

c=n/v

volume = dcm3. !!don’t forget to convert if in cm3!!

Question 5

how to convert concentration from mol/dm3 to g/dcm3

Answer 5

Mass in g = moles x rfm

Question 6

Avogadro’s Law

molar volume of any gas at RTP

Answer 6

24

Question 7

how to calculate gas volumes in reactions if you know the masses

Answer 7

Work backwards!
What formula do you need? e.g. v = moles x 24
How do you get the component parts? e.g. moles of known mass of reactant
Ratio of reactant to product (e.g. number at front)
apply formula