What are the molecular formulas of benzene and acetylene?
benzene and acetylene have the same empirical formula, CH. however, benzene has a molar mass of 78 g, and acetylene has a molar mass of 26 g
Answer:
Hi,
It seems that you don't understand the meaning od empirical formula.
In chemistry, the empirical formula of a chemical compound is a simple expression of the relative number of each type of atom (called a chemical element) in it. An empirical formula makes no reference to isomerism, structure, or absolute number of atoms. Empirical formulae are the standard for ionic compounds, such as CaCl2, and for macromolecules, such as SiO2. The term empirical refers to the process of elemental analysis, a technique of analytical chemistry used to determine the relative percent composition of a pure chemical substance by element.
In contrast, the molecular formula identifies the absolute number of atoms of such element to be found in each discrete molecule of that compound.
For example, n-hexane, a chemical compound has the molecular formula CH3CH2CH2CH2CH2CH3, implying that it has a straight chain structure, 6 carbon atoms, and 14 hydrogen atoms. Hexane's molecular formula is C6H14, and its empirical formula would be C3H7 showing a C:H ratio of 3:7.
As you have asked
Benzene that is C6H6
Here the ratio of carbon and hydrogen is 1:1
And
Acetylene that is C2H2
Here also the ratio is 1:1
Hence the empirical formula is the same but different masses.
I hope you get it.
benzene- C6H6
acetylene- C2H2
Acetylene is C2H2
Benzene is C6H6
The empirical formula is CH .. That's worth 12 + 1 = 13.
So 78/13 = 6. Thus benzene must have 6 CH units. Get it?
Both have the same number of carbon (C) and hydrogen atoms (H). But benzene's formula is C6H6; acetylene is C2H2.
A single molecule of benzene has exactly 3 times as many atoms as acetylene. So a mole of benzene will have 3 times the mass.
Benzene is an Aromatic C6H6 in ring structure having alternating single and double bonds: As below: -
CH-CH=CH-CH=CH-CH= The final 'C' double bond is attached to the 1st carbon to form the ring structure.
...Equals 12 x 6 + 1 x 6 = 78mol.mass.
Acetylene is an Alkyne having a triple bond between its 2 carbons and 1 'H' on each carbon.
H-C≡C-H = 12 x 2 + 1 x 2 = 26mol/mass.
'C' to 'H' in each case is 1:1 = CH
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