An elemental analysis is performed in an unknown compound. it is found to contain 40.0 % mass in carbon, 6.71% mass in hydrogen, and the remaining mass in oxygen. determine its empirical formula. the formula mass of the unknown is independently determined to be 90.08 g/mol, determine the unknown’s molecular formula

Molecular formula will be

Explanation:

If percentage are given then we are taking total mass is 100 grams.

So, the mass of each element is equal to the percentage given.

Mass of C= 40 g

Mass of H = 6.71 g

Mass of O = 100 - (40+6.71 ) = 53.29 g

Step 1 : convert given masses into moles.

Moles of C =

Moles of H =

Moles of O =

Step 2 : For the mole ratio, divide each value of moles by the smallest number of moles calculated.

For C =

For H =

For O =

The ratio of C: H: O= 1 : 2: 1

Hence the empirical formula is

The empirical weight of = 1(12)+2(1)+1(16)= 30g.

The molecular weight = 90.08 g/mole

Now we have to calculate the molecular formula:

The molecular formula will be=

Molecular formula will be

the density of gold = 19.3 g/cm3

the relation between density and mass and volume is

density = mass / volume

given :

mass of gold = 13 g

density = 13g / volume = 19.3

volume = 13 /19.3 = 0.67 cm^3

thus volume of gold nugget = 0.67 cm^3