Question 2.2
NCERT Class XI Chemistry
(i) Calculate the total number of electrons present in one mole of methane. (ii) Find (a) the total number and (b) the total mass of neutrons in 7 mg of 14C. (Assume that mass of a neutron = 1.675 × 10-27 kg). (iii) Find (a) the total number and (b) the total mass of protons in 34 mg of NH3 at STP. Will the answer change if the temperature and pressure are changed ?
Video Explanation
(detailed solution given after this video)
Please watch this youtube video for a quick explanation of the solution:
Solution in Detail
1 molecule
electrons
electrons in 1 mol =
we know 14 g of mol
mol
mol
atoms
atoms . . . (1)
but
1 atom contains A - Z = 8 neutrons
total mass = kg
Given 34 mg NH3 i.e., 0.034 g NH3
now, molar mass NH3 = 14 + 3 x 1 = 17 g/mol
∴ 17 g NH3 = 1 mol
∴ 0.034 g NH3 = mol
molecules . . . (1)
no. of protons in an atom = Z
∴ protons in N = 7, H = 1
∴ 1 molecule NH3 = 7 + (1 x 3) = 10 protons
∴ contain
protons Ans
Will the answer change if the temperature and pressure are changed ?
Ans: If temperature and pressure are changed in such a way that the number of moles of the gas remain same, then the answer will not change.
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