Stoichiometry

Question 1

what are the 4 equations i need to know?

Answer 1

moles = mass /Mr or Ar

moles = M x V/1000

moles = v/24000

ratio

Question 2

when do you use moles =mass/Mr or Ar?

Answer 2

in any situation given you have the correct information

Question 3

when do you use moles = m x v /1000?

Answer 3

solutions M=concentration

Question 4

when do you use moles = v/24000?

Answer 4

gas

Question 5

when do you use ratio?

Answer 5

when comparing moles

Question 6

what do you do if dm3 is asked for as an answer?

Answer 6

divide your cm3 answer by 1000

Question 7

how do you work out the water of crystallisation?

Answer 7

1. calculate the mass of water
2. calculate the moles of water
3. calculate the moles of the compound
4. divide by the smallest number

Question 8

what is the empirical formula?

Answer 8

the simplest formula of elements in a compound

Question 9

How do you find the empirical formula?

Answer 9

1. make a table with the element names in
2. add the mass or percent given
3. add Ar
4. find moles
5. divide by the smallest number

Question 10

How do you find out the molecular formula?

Answer 10

1. find the empirical mass
2. formula mass / empirical mass
3. = molecular formula