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

Molar mass of sucrose (C12 H22 O11) = 342g/mole

Thus,


Number of moles of sucrose = Given mass/ Molar Mass


=


1 mol of sucrose contains = 1× NA sucrose molecules = 11 x NA atoms of oxygen


0.01 mol of sucrose (C12 H22 O11) contains = 0.01 × 11 × NA atoms of oxygen


= 0.11× NA atoms of oxygen


Molar mass of water = 18g/mole


Thus, Number of moles of water =


1 mol of water (H2O) contains = 1×NA water molecules = 1 x NA atoms of oxygen


Total number of oxygen atoms = Number of oxygen atoms from sucrose + Number of oxygen atoms from water


= 0.11 NA + 1.0 NA = 1.11NA


Number of oxygen atoms in solution = 1.11 × Avogadro’s number


= 1.11 × 6.022 ×1023


= 6.68 × 1023

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