Calculate the molecular mass of the following:
(i) H2O
(ii) CO2
(iii) CH4
Molecules are made up of atoms & are quite small, therefore the actual mass of a molecule cannot be detrmined.It is expressed as the relative mass.C-12 isotope is used to express the relative molecular masses of substances.Thus molecular mass of a substance may be defined as: the average relative mass of its molecule as compared to the mass of carbon atom taken as 12 amu.
(i) H2O:
The molecular mass of water, H2O
= (2 × Atomic mass of hydrogen) + (1 × Atomic mass of oxygen)
= [2(1.0084) + 1(16.00 u)]
= 2.016 u + 16.00 u
= 18.016
= 18.02 u
(ii) CO2:
The molecular mass of carbon dioxide, CO2
= (1 × Atomic mass of carbon) + (2 × Atomic mass of oxygen)
= [1(12.011 u) + 2 (16.00 u)]
= 12.011 u + 32.00 u
= 44.01 u
(iii) CH4:
The molecular mass of methane, CH4
= (1 × Atomic mass of carbon) + (4 × Atomic mass of hydrogen)
= [1(12.011 u) + 4 (1.008 u)]
= 12.011 u + 4.032 u
= 16.043 u
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Welcome to the NCERT Solutions for Class 12 Chemistry - Chapter . This page offers a step-by-step solution to the specific question from Excercise 1 , Question 8: Ortho and para nitrophenols are more acidic than phenol. Draw the resonance structures of the corres....
Comments
why is it that in some books the resonance structures of o and p nitrophenol is given upto only the fifth resonating structure??
Para last structure is wrong correct it
In 5th resonating structure of p-isomer,double bonds should b b/w carbon no.2&3,4&5 but here double bonds are given b/w carbon no.1&2,4&5 which is not right.
How can oxygen have 3 lone pairs.
Yes you are right the last structure will not have a double bond with oxygen atom.only a single bond will be their in the last structure because the electron involved in making double bond between carbon and oxygen has been transferred to the oxygen atom
The structure of para is wrong as in the last step the topmost carbon is having 5 bonds which is not possible.