Question

log 2.06 mol = 4.04 molo 0.51 2. Determine the empirical formula of a substance that has a molar mass of 62g/mole if a sample of it has a mass of 7.170g (consisting of 2.776g of C, 0.690g of H, 3.700g O). (BOX YOUR ANSWER)

Answer 1

2.

total mass of sample m =7.170 g

mass of C in it m₁= 2.776 g

mass % of carbon in sample =m_1/m*100

=2.776/7.170*100

=38.72 %

mass of O in it m₃= 3.7 g

mass % of oxygen in sample =m_3/m*100

= 3.7/7.170*100

=51.60%

mass of H in it m₂= 0.690 g

mass % of hydrogen in sample =m_2/m*100

=0.690/7.170*100

= 9.6%

The empirical formula of a compound can be calculated using the following method

element	mass %	atomic weight	relative number of atom	simplest ratio	simplest whole number ratio
C	38.2	12	38.2/12=3.183	3.183/3.183=1	1
H	9.6	1	9.6/1=9.6	9.6/3.183=3.02	3
O	51.6	16	51.6/16=3.225	3.225/3.183=1.03	1

ratio between C:H:O = 1:3:1

emperical formula containing .C , H and O is C₁H₃O₁