Why is the extraction of copper from pyr | Class 12 Chemistry Chapter General Principles and Processes of Isolation of Elements, General Principles and Processes of Isolation of Elements 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


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Comments

  • aadil
  • 2021-07-01 10:38:43

The value of ∆fG ⊝ for formation of Cr2O3 is -540 KJ mol-1 and that of Al2O3 -827 KJ mol-1 . Is the reduction of Cr2O3 possible with Al ?


  • Qwert
  • 2019-10-12 18:43:03

Ok partha,you try your best


  • Kumar sid
  • 2019-08-23 12:46:40

Bahot hi aacha


  • Santya kumar
  • 2019-06-09 12:11:35

Nice answer


  • partha
  • 2018-04-25 10:15:08

Nice answer .could hav tried litle mich better


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 3: Why is the extraction of copper from pyrites more difficult than that from its oxide ore through red....