Question

3.42 of sucrose is dissolved in 18 g of water in a beaker. The number of oxygen atoms in the solution are:

A. 6.68 x 10²³

B. 6.09 x 10²²

C. 6.022 x 10²³

D. 6.022 x 10²¹

Answer 1

Molar mass of sucrose = C₁₂H₂₂O₁₁

= 12× 12 + 1× 22 + 16 × 11 = 342g/mol

Number of moles = \(\frac{Mass\,of\,glucose}{Molar\,mass\,of\,sucrose}\)

Number of moles = \(\frac{3.42 g}{342g/mol}\)

⇒Number of moles = 0.01

Sucrose(C₁₂H₂₂O₁₁) contains 11 oxygen atoms

⇒11 x 6.022 x 10²³

For 0.01 moles of sucrose

⇒ 0.01 x 11 x 6.022 x 10²³

Now, Molar mass of water = H₂O = 2 × 1 + 16 = 18g/mol

⇒ Number of moles = 1

Sucrose (H₂O) contains 1 oxygen atom = 6.022 × 10²³

For 1 mole of water = 6.022 × 10²³

Now, add the both values: 6.6 × 1022 + 6.022 × 10²³

We get 6.68 × 10²³ atoms. Hence, the option (a) is correct.