Question

How many grams are there in the following?
i) 1 mole of chlorine molecule, Cl2 ii) 2 moles of sulphur molecules, S8
iii) 4 moles of ozone molecules, O3 iv) 2 moles of nitrogen molecules, N2

Answer 1

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Satyanarayana answered 3 year(s) ago

 What mass of oxygen, O2 will contain the same number of molecules as 2.5 moles of chlorine, Cl2 ?

Class-IX Chemistry

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Asked by Rushil

Mar 6

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Satyanarayana , SubjectMatterExpert

Member since Apr 24 2013

Ans:
Number of molecules in 1 mole of Chlorine molecule = 6.023*1023 number of molecules
Number of molecules in 2.5 moles of Chlorine molecule = (2.5*6.023*1023)
= (15.0575*1023) number of molecules.
6.023 *1023 number of molecules has a mass of 32 grams
15.0575*1023 number of molecules will have a mass of = X grams
X = (15.0575*1023)*(32)/(6.023 *1023)
= (2.5*32)
= 80 grams
80 grams mass of O2 will contain the same number of molecules as 2.5 moles of Cl2

Answer 2

We know n=w/M. So, w = n x M       

i) 1 mole Chlorine Cl2.

Atomic mass number of Chlorine is 35.5.

So, M= 35.5 X 2 =71g. So, w / 1 mole of Cl2 weighs = 1 × 71 = 71 gm.

ii) 2 moles of Sulphur S8.

Atomic mass number of Sulphur is 32. So, M= 8 X 32 = 256 g.

So, 2 moles of Sulphur molecules weigh =2× 256 = 512gm .

iii) 4 moles of Ozone O3. Atomic mass number of Ozone is 48.

So, M= 3 X 48 = 144 g.

So, the weight of 4 moles of ozone is = 4 × 144 = 576gm.

iv) 2 moles of Nitrogen N2.

Atomic mass number of Nitrogen is 14.

So, M= 2 X 14 =28 g.

Thus, 2 moles of Nitrogen weigh = 2 X 28 = 56gm.