A compound contains 7 carbon atoms, 2 oxygen atoms and \(9.96 \times 10^{-24} \mathrm{~g}\) of other elements. The molecular mass of compound is \(\left(N_{\mathrm{A}}=6 \times 10^{23}\right)\) (a) 122 (b) 116 (c) 148 (d) 154

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Answer: (b) 116

Step by step solution

01

Calculate mass of carbon atoms

The given compound contains 7 carbon atoms. The atomic mass of carbon is 12 g/mole. Since the atomic mass is the mass of one mole of a substance (1 mole contains Avogadro's number of particles), we can calculate the total mass of carbon atoms in the compound. $$ \text{Total mass of carbon atoms} = \text{number of carbon atoms} \times \text{atomic mass of carbon} $$ $$ \text{Total mass of carbon atoms} = 7 \times 12 = 84 \mathrm{~g/mol} $$
02

Calculate mass of oxygen atoms

Now, let's calculate the total mass of oxygen atoms in the given compound. The compound contains 2 oxygen atoms, and the atomic mass of oxygen is 16 g/mole. $$ \text{Total mass of oxygen atoms} = \text{number of oxygen atoms} \times \text{atomic mass of oxygen} $$ $$ \text{Total mass of oxygen atoms} = 2 \times 16 = 32 \mathrm{~g/mol} $$
03

Calculate mass of other elements

We are given the mass of other elements in the compound, which is \(9.96 \times 10^{-24}\mathrm{~g}\). In order to find the mass of the other elements per mole, we need to use Avogadro's number, which is \(6 \times 10^{23}\). $$ \text{Mass of other elements per mole} = \frac{\text{mass of other elements}}{\text{Avogadro's number}} $$ $$ \text{Mass of other elements per mole} = \frac{9.96 \times 10^{-24}\mathrm{~g}}{6 \times 10^{23}} = 1.66 \times 10^{-03} \mathrm{~g/mol} $$
04

Calculate the molecular mass of the compound

Now, we can find the molecular mass of the compound by adding the total mass of carbon atoms, oxygen atoms, and other elements. $$ \text{Molecular mass of compound} = \text{Total mass of carbon atoms} + \text{Total mass of oxygen atoms} + \text{Mass of other elements per mole} $$ $$ \text{Molecular mass of compound} = 84 + 32 + 1.66 \times 10^{-03} = 116.00166 \mathrm{~g/mol} $$ Since 116.00166 is closest to 116 among the given options, the correct molecular mass of the compound is: (a) 122 (b) 116 (c) 148 (d) 154 The answer is (b) 116.

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Most popular questions from this chapter

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