Question

9.
Assume that human body is 80% water. Calculate the number of molecules of
water that are present in the body of a person whose weight is 65 kg.​

Answer 1

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==>>First we will calculate amount of water in 65kg body

given 80% of body weight is water

80% of 65kg= 65*(80/100)= 52kg

first find number of moles by dividing 1kg by molar mass

1000/18=55.56 moles per kg

Now to calculate molecules multiply it by Avagadro number we get

55.56*6.023*1023 =3.344*1025

This is number of molecules in 1kg of water

Now multiply it by 52kg we get

3.344*1025 * 52 = 173.89*1025 molecules