Question

1. Calculate the following:
a. Mass of 0.5 mole of oxygen gas
b. Number of particles in 24 g of magnesium
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Answer 1

Explanation:

3.011 x 1023 atoms of oxygen. (iii) 6.022 x 1024 molecules of oxygen. (Given atomic mass of 0 = 16u; No = 6.022 x 1023 per mole)

1 mole of MgO contains Avogadro's number of molecules which is 6.023×10

23

molecules.

0.5 mole of MgO will contain 0.5×6.023×10

23

=3.0115×10

23

molecules.

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Answer 2

Answer:

a) example, molecular mass of a water molecule is 18 amu (2 amu for 2 hydrogen atoms, and 16 amu for one oxygen atom). So, mass of one mole of water would be 18 grams. Thus, mass of 0.5 moles of water would be 9 grams.

b) From the equation above we get 1 amu = 1g/NA or 1 amu = 1.66054x10^-24 g. Thus, a mole of magnesium atoms has a mass of NA x 24.305 amu x (1.66054x10^-24 g/amu) = 24.305 g. A mole of magnesium atoms has a mass of 24.305 g.

Explanation:

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