Question

Calculate the actual mass of: (1) an hydrogen atom
(2) a molecule of NH3 (3) the atom of silver
(4) the molecule of oxygen
(5)0.25gram of atom of calcium

Answer 1

the gram atomic weight of hydrogen: 1gms
∴ 1mole of H= 1gms
∴ 6.023×10²³atoms of H= 1gms
∴1 atom of H=1/(6.023×10²³)
∴1 atom of H=1.6×10⁻²³gms
the gram molecular wt of NH₃= 14+3×1= 17gms
1 mole of NH₃= 17gms
∴6.023×10²²molecules of NH₃= 17gms
∴1 molecule of NH₃= 17/6.023×10²³
=2.82251×10⁻²³gms
the gram atomic wt of oxygen= 16gms
∴6.023×10²³ atoms of oxygen= 16gms
∴1 atom of oxygen= 16/6.023×10²³
=2.654×10⁻²³gms
the gram atomic weight of Ca= 40gms
0.25gram atoms of Ca= 40gms×0.25
∴0.25gram atom of Ca=10gms

Answer 2

Hi friend,
1)Actual mass of an hydrogen atom= 1 gram
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2) A molecule of NH3has molecular mass = 1X14+1X3
                   
                                                                   =14+3

                                                                   = 17 gram
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3) 1 Mole of Ag = 6.022X10²³atoms= 107 g

                          1 atom                   =107/6.022 x 10²³

                                                        = 17.76X 10-²³ gram
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4) O2= 1 mole =32 gram
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5)  gram atomic mass of chlorine = 40 g
atomic  mass in 0.25g  atoms       = 40 x 0.25
                                                      = 10 g
      

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