Question

a composition of a organic compound found to contain 39.9%of carbon67%of hydrogen and remaining being oxygen the molar mass of the compound is 180 determine its empirical formula​

Answer 1

Question:

A composition of an organic compound is found to contain 39.9 % of carbon, 6.7% of hydrogen and remaining being oxygen. The molar mass of the compound is 180. Determine its empirical formula and molecular formula.

Answer:

Empirical formula of the compound = CH₂O

Molecular formula = C₆H₁₂O₆

Explanation:

$\Large{\underline{\bf{Given:}}}$

• Mass of carbon = 39.9 g
• Mass of hydrogen = 6.7 g
• Mass of oxygen = (100 - (39.9 + 6.7) ) = 53.4 g

$\Large{\underline{\bf{To\:Find:}}}$

• Empirical formula
• Molecular formula

$\Large{\underline{\bf{Solution:}}}$

➟ First we have to find the number of moles of each element present in the compund.

➟ The number of moles of a given compound is given by,

    Number of moles = Given mass/Molar mass

➟ Number of moles of carbon = 39.9/12

    Number of moles of carbon = 3.325 moles

➟ Number of moles of hydrogen = 6.7/1

    Number of moles of hydrogen = 6.7 moles

➟ Number of moles of oxygen = 53.4/16

    Number of moles of oxygen = 3.34 moles

➟ Now we have to find the simplest whole number ratio of all the elements.

    Simplest whole number ratio of carbon = 3.325/3.325 = 1

    Simplest whole number ratio of hydrogen = 6.7/3.325 = 2

    Simplest whole number ratio of oxygen = 3.34/3.325 = 1

➟ Hence,

    Empirical formula of the compound = CH₂O

➟ Now we have to find the molecular mass of the compund.

    Molecular mass = 12 + 2 + 16 = 30

➟ Now we know that,

    Molar mass/Molecular mass = n

    n = 180/30

    n = 6

➟ We know that,

    Molecular formula = n × Empirical formula

    Molecular formula = 6 × CH₂O

    Molecular formula = C₆H₁₂O₆