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 3: Why is N2 less reactive at room temperature?....
Comments
If the size is small then the bond dissociation enthelpy or energy is high due to the the electrons are tightly bonded and having stronger nuclear charge bcz only the number ofelectrons are much as compared to their size
Give the increasing order acidic stronger of hclo ,hclo2, hclo3 ,hclo4?
Thanks
Thank u so much for helping
Excellent it is very useful
For boards, specific answer is required. Nitrogen forms pÏ-pÏ bond with other nitrogen due to small size and high electronegativity. Thus they exist as a very stable diatomic molecule with Bond enthalpy = 941.4kJ/mol which is very difficult to overcome. Thus they are stable at room temperature and less reactive
reply to simran question dinitrogen is unreactive at room temperature. The room temperature varies according to the conditions in which dintrogen is kept.But with the increase in temperature dintrogen reactivity increases.It Liquefies at 77 K and freezes at63 K
NOT PROPER DUDE IF I ASK YOU AT WHAT TEMP IT REACT THAN WHAT YOU SAY
The nitrogen atom is small in size but the two nitrogen atoms are attached to each other by tripple bond.So three bonds have to be broken to make N2 reactive ,as a result the bond dissociation energy is high.
If the size is small then why is the bond dissociation energy high?