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

Calculate the mass of urea (NH2CONH2) re | Class 12 Chemistry Chapter Solutions, Solutions 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

Talib khan
2019-12-09 13:57:40

Thanks saral study

Jerina
2019-11-25 07:05:39

That's awesome thank you so much

Arushi
2019-11-18 10:13:26

Thank you.

G Akhil
2019-11-10 12:57:58

Thank you very much saral study

Riya
2019-11-05 22:06:19

Thanks saral study.

Vimatsh
2019-08-28 20:30:44

Thanks

Pawan
2019-07-17 20:11:19

Please clear all method don't skip any method

Nasim akram
2019-07-17 09:48:38

Thanks

Naman
2019-07-02 18:13:17

But in ncert there i wrong answer

Ankita
2019-06-14 21:15:23

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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 4: Calculate the mass of urea (NH2CONH2) required in making 2.5 kg of 0.25 molal aqueous solution.....

Calculate the mass of urea (NH2CONH2) re | Class 12 Chemistry Chapter Solutions, Solutions NCERT Solutions

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