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Zorluk: ZorThe Mole Concept, Avogadro's Constant, and Molar Mass

A sample of dinitrogen tetraoxide (N2O4\text{N}_2\text{O}_4) gas occupies a volume of 5.6 dm35.6\text{ dm}^3 at standard temperature and pressure (STP). What is the total number of oxygen atoms contained in this sample? [Molar volume of gas at STP=22.4 dm3mol1,NA=6.02×1023 mol1][\text{Molar volume of gas at STP} = 22.4\text{ dm}^3\text{mol}^{-1}, N_A = 6.02 \times 10^{23}\text{ mol}^{-1}]

  1. 6.02×10236.02 \times 10^{23}Cevap
  2. B
    5.62×10235.62 \times 10^{23}
  3. C
    1.51×10231.51 \times 10^{23}
  4. D
    9.03×10239.03 \times 10^{23}

Cevap

6.02×10236.02 \times 10^{23} oxygen atoms
The sample contains 0.25 mol0.25\text{ mol} of N2O4\text{N}_2\text{O}_4 gas because 5.6 dm3/22.4 dm3mol1=0.25 mol5.6\text{ dm}^3 / 22.4\text{ dm}^3\text{mol}^{-1} = 0.25\text{ mol}. Since each molecule of N2O4\text{N}_2\text{O}_4 contains 4 oxygen atoms, the total amount of oxygen atoms is 0.25×4=1.0 mol0.25 \times 4 = 1.0\text{ mol}. Multiplying 1.0 mol1.0\text{ mol} by Avogadro's constant (6.02×1023 mol16.02 \times 10^{23}\text{ mol}^{-1}) yields 6.02×10236.02 \times 10^{23} oxygen atoms.

Adım Adım Çözüm

1
Calculate the number of moles of dinitrogen tetraoxide (N2O4\text{N}_2\text{O}_4) gas at STP
n(N2O4)=VolumeMolar Volume=5.6 dm322.4 dm3mol1=0.25 moln(\text{N}_2\text{O}_4) = \frac{\text{Volume}}{\text{Molar Volume}} = \frac{5.6\text{ dm}^3}{22.4\text{ dm}^3\text{mol}^{-1}} = 0.25\text{ mol}
At STP, one mole of any ideal gas occupies 22.4 dm322.4\text{ dm}^3.
2
Determine the moles of oxygen atoms present in 0.25 mol0.25\text{ mol} of N2O4\text{N}_2\text{O}_4
n(O)=0.25 mol×4=1.0 moln(\text{O}) = 0.25\text{ mol} \times 4 = 1.0\text{ mol} of oxygen atoms
Each molecule of N2O4\text{N}_2\text{O}_4 contains 4 oxygen atoms.
3
Compute the absolute number of oxygen atoms using Avogadro's constant
N(O)=n(O)×NA=1.0 mol×6.02×1023 mol1=6.02×1023N(\text{O}) = n(\text{O}) \times N_A = 1.0\text{ mol} \times 6.02 \times 10^{23}\text{ mol}^{-1} = 6.02 \times 10^{23} atoms
One mole of any substance contains NAN_A particles.

Anahtar Kavram

Molar gas volume at STP and Avogadro's constant stoichiometric conversions
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