The density of water is 1.00g/mL at 4'C. How many water molecules are present in 2.56mL of water at this temperature?

Expert Answers

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Density = mass/volume.

Mass = Density * Volume.

Given

density = 1g/ml

Volume = 2.56 ml

Mass = 1 * 2.56 = 2.56 g.

We know 1 mole contain 6.02 x 10^23 molecules.

Moles = mass/molar mass

         = 2.56/18    [ Molar mass of water = 18]

         = 0.142.

Therefore 0.142 moles of water will contain 0.142 * 6.02 x 10^23 molecules = 8.5484 * 10^22 molecules.

So 2.56 ml of water at that temperature contain 8.5484 * 10^22 molecules.

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