formulae

Question 1

what is empirical formula

Answer 1

the simplest whole number ratio of atoms of each element that are in a compound
-it is also the ratio of moles of
atoms.

Question 2

what is the molecular formula

Answer 2

the actual number of
atoms of each element in a compound

Question 3

how to calculate empirical formula

Answer 3

-divide quantities given (percentage or masses) by molecular formula
-divide by smallest quantity
-make the ratio into whole numbers

Question 4

how to calculate molecular formula of a compound

Answer 4

1) find out the empirical formula of the compound
2) Find out the relative mass of the empirical formula
3) divide the relative molecular mass of the compound by its
relative mass of the empirical formula to determine the number of
empirical formula units
4) multiply this value by the empirical formula to determine the
molecular formula

Question 5

what is a hydrated salt

Answer 5

a salt that contains water of crystallisation
as part of its structure.

Question 6

what is an anhydrous salt

Answer 6

– a salt that has no water of crystallisation
as part of its structure

Question 7

what is the name of substances that absorb water from the atmosphere

Answer 7

hygroscopic

Question 8

how to calculate the formula of hydrated salt

Answer 8

-Calculate the moles of anhydrous salt
-Calculate the moles of water
-Find the smallest whole number ratio

Question 9

what is the experimental value for the moles in the hydrated salt lower than expected

Answer 9

not all water removed–> moles of anhydrous salt higher

Question 10

how to work out identity of salt from the hydrated salt formula

Answer 10

1. Find out number or moles of water lost
2. Find out the ratio of anhydrous salt to
   water
3. Find out the number of moles of
   anhydrous salt
4. Find out molar mass of anhydrous salt
5. Identity of X