
The empirical formula of a compound is CH. Its molecular weight is 78. The molecular formula of the compound will be:
(A) - C H
(B) - C H
(C) - C H
(D) - C H
Answer
454.3k+ views
3 likes
Hint: Empirical formula is the simplest whole-number ratio of atoms in any compound whereas molecular formula is exactly the number of each atom present in any compound. The empirical weight of CH can be calculated and then divided with the molecular weight. The number, thus, obtained would be the exact number of carbon and hydrogen atoms in the compound.
Complete answer:
According to the question, the empirical formula of a compound is CH, i.e. it is the lowest whole number ratio of that particular compound.
-> Now, we will calculate the empirical weight of CH.
Empirical weight = atomic mass of C + atomic mass of H = 12+1 = 13 g/mol.
->The molecular weight of the compound is given, i.e. 78 g/mol.
-> Now, we have to calculate the molecular formula;
Molecular weight = n empirical weight, n represents the no. of atoms.
n = Molecular weight / empirical weight = 78 /13 = 6, or
n = = = 6
->So, molecular formula = (CH) = (CH) =C H ; in this case we substituted the calculated value of n.
->Therefore, the molecular formula of the compound having the molecular weight 78 g/mol is (D) - C H .
Hence option ‘D’ is the correct answer.
Note:: The significance of empirical formula in chemistry is that it makes the stoichiometry calculations very easy and handy, especially when it comes in organic chemistry where a long chain of carbohydrates and proteins is there. Also, it could provide an avenue to find the molecular formula of any unknown compound by finding empirical formula experimentally and using other tools.
Complete answer:
According to the question, the empirical formula of a compound is CH, i.e. it is the lowest whole number ratio of that particular compound.
-> Now, we will calculate the empirical weight of CH.
Empirical weight = atomic mass of C + atomic mass of H = 12+1 = 13 g/mol.
->The molecular weight of the compound is given, i.e. 78 g/mol.
-> Now, we have to calculate the molecular formula;
Molecular weight = n
n = Molecular weight / empirical weight = 78 /13 = 6, or
n =
->So, molecular formula = (CH)
->Therefore, the molecular formula of the compound having the molecular weight 78 g/mol is (D) - C
Hence option ‘D’ is the correct answer.
Note:: The significance of empirical formula in chemistry is that it makes the stoichiometry calculations very easy and handy, especially when it comes in organic chemistry where a long chain of carbohydrates and proteins is there. Also, it could provide an avenue to find the molecular formula of any unknown compound by finding empirical formula experimentally and using other tools.
Latest Vedantu courses for you
Grade 11 Science PCM | CBSE | SCHOOL | English
CBSE (2025-26)
School Full course for CBSE students
₹41,848 per year
Recently Updated Pages
Master Class 11 Business Studies: Engaging Questions & Answers for Success

Master Class 11 Economics: Engaging Questions & Answers for Success

Master Class 11 Accountancy: Engaging Questions & Answers for Success

Master Class 11 Computer Science: Engaging Questions & Answers for Success

Master Class 11 English: Engaging Questions & Answers for Success

Master Class 11 Maths: Engaging Questions & Answers for Success

Trending doubts
Which one is a true fish A Jellyfish B Starfish C Dogfish class 11 biology CBSE

Difference Between Prokaryotic Cells and Eukaryotic Cells

1 ton equals to A 100 kg B 1000 kg C 10 kg D 10000 class 11 physics CBSE

One Metric ton is equal to kg A 10000 B 1000 C 100 class 11 physics CBSE

How much is 23 kg in pounds class 11 chemistry CBSE

Net gain of ATP in glycolysis a 6 b 2 c 4 d 8 class 11 biology CBSE
