Amount of substance

1. Calculate the number of nitric oxide molecules in a container that contains 4.5 mol of this gas.

Solution:

We start from the equation for calculating the amount of substance:

N(NO)  = n(NO).NA = 4.5 mol × 6.022 × 1023 = 2.7 × 1024

The container contains 2.7 × 1024 NO molecules.

2. What amount of substance corresponds to 1.806 × 1027 carbon atoms?

Solution:

We use the relation for the amount of substance.

substance-amount-2.gif

The amount of carbon substance containing 1.806 × 1027 atoms is 3 kmol.

3. How many molecules are in a container containing 2.5 mol of carbon dioxide?

Solution:

We use a similar procedure as in example 2.

1.5 × 1024 molecules.

4. Calculate the amount of substance:

  • a) 2.58 × 1027 atoms of aluminum
  • b) 5.55 × 1019 sodium cations
  • c) 8.68 × 1022 chloride anions
  • d) 1.75 × 1025 molecules of white phosphorus (P4)
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5. The charge of an electron is 1.6 × 10-19 C. What is the charge of 1 mol of electrons (Faraday’s constant)?

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6. How many silver atoms are contained in 1 cm3 of this metal, which has a density of ρ = 10.5 × 103 kg·m-3?

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7. What amount of substance of H2O is in one liter of water?

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8. What amount of sodium is in 10 g of NaCl? How many chlorine atoms correspond to this amount of sodium in the compound?

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9. What amount of substance corresponds to 1 g of H2SO4 and 200 g of CH4?

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10. What amount of aluminum is in a cube with an edge of 10 cm? (use data from chemical tables)

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