During nuclear explosion, one of the pro | Class 12 Chemistry Chapter Chemical Kinetics, Chemical Kinetics NCERT Solutions

Question:

Calculate the molecular mass of the following:
(i) H2O
(ii) CO2
(iii) CH4

Answer:

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


Study Tips for Answering NCERT Questions:

NCERT questions are designed to test your understanding of the concepts and theories discussed in the chapter. Here are some tips to help you answer NCERT questions effectively:

  • Read the question carefully and focus on the core concept being asked.
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Comments

  • aarchisa
  • 2019-11-12 12:09:29

cos its radioactive


  • Shreya
  • 2019-06-01 13:55:32

How do we know it is a first order reaction?


  • Shubham
  • 2019-02-17 17:50:59

Nicely explained it


  • Shubham
  • 2019-02-17 17:50:04

Thanks a lot for this And it's really a wonderful site


  • bobby
  • 2019-01-11 14:37:20

thank you


  • bobby
  • 2019-01-11 14:36:29

thank you


  • Demosthenes
  • 2017-09-16 23:29:05

Thank you so very much - the chemistry and biology solutions are very comprehensive, and easy to understand. I really appreciate the efforts taken by the site's creators.


Comment(s) on this Question

Welcome to the NCERT Solutions for Class 12 Chemistry - Chapter . This page offers a step-by-step solution to the specific question from Excercise 2 , Question 17: During nuclear explosion, one of the products is 90Sr with half-life of 28.1 years. If 1μg of 90S....