Respuesta :
Answer:
Molecular formula of the compound = H₂CO₃
Explanation:
First, the empirical formula of the compound is determined
Percentage by mass of each element is given as shown below:
H = 3.3% ; C = 19.9%; O = 77.4%
Mole ratio of the elements= percentage mass/ molar mass
H = 3.3/ 1 = 3.3
C = 19.3/12 = 1.6
O = 77.4/16 = 4.8
whole number ratio is obtained by dividing through with the smallest ratio
H = 3.3/1.6; C = 1.6/1.6; O = 4.8/1.6
H : C : O = 2 : 1 : 3
Empirical formula = H₂CO₃
Molecular formula/mass = n(empirical formula/mass)
60 = n(2*1 + 12*1 + 16*3)
60 = n(62)
n = 60/62 = 0.96
n is approximately = 1
Therefore, molecular formula of the compound = (H₂CO₃) * 1
Molecular formula of the compound = H₂CO₃
The molecular formula of a compound composed of 3.3% H, 19.3% C, and 77.4% O and a molar mass of approximately 60 g/mol is CH2O3.
HOW TO CALCULATE MOLECULAR FORMULA:
- The molecular formula of an unknown compound can be calculated from the empirical formula. The empirical formula can be calculated as follows:
- C = 19.3% = 19.3g
- H = 3.3% = 3.3g
- O = 77.4% = 77.4g
- First, we calculate the number of moles in each element by dividing by their respective atomic mass.
- C = 19.3g ÷ 12g/mol = 1.61mol
- H = 3.3g ÷ 1g/mol = 3.3mol
- O = 77.4g ÷ 16g/mol = 4.84mol
- Next, we divide by the smallest mole value.
- C = 1.61mol ÷ 1.61 = 1
- H = 3.3mol ÷ 1.61 = 2.05
- O = 4.84mol ÷ 1.61 = 3.01
- Approximately, the empirical ratio of CHO is 1:2:3. Hence, the empirical formula is CH2O3.
- {CH2O3}n = 60g/mol
- {12 + 2 + 48}n = 60
- 62n = 60
- n = 60 ÷ 62
- n = 0.968
- n = 1
- Therefore, the molecular formula of a compound composed of 3.3% H, 19.3% C, and 77.4% O and a molar mass of approximately 60 g/mol is CH2O3.
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