What is the fraction of the mass of water due to neutrons?

Soln:

Mass of 1 mole of a substance is equal to its relative atomic or molecular mass in grams. Mass of one mole (Avogadro Number) of neutrons =1g

Mass of one neutron = 1/ Avogadro number(NA) g

Mass of one molecule of water = Molar mass / NA = 18/ NA g

The molar mass of water is

18.015 g/mol. This was

calculated by multiplying the atomic weight of hydrogen (1.008) by two and adding the result to the weight for one oxygen (15.999)

Mass of one molecule of water = Molar mass / NA = 18/ NA g Avogadro number(NA) =6.022 x 1023mol¯ 1

There are 8 neutrons in one atom of oxygen

Number of neutrons in oxygen= number of oxygen - Atomic number of oxygen Oxygen's atomic weight= 15.9994

increases with an increase in temperature. Therefore the mass is 16

Therefore number of neutrons= 16 - 8 = 8

Mass of one neutron = 1/ Avogadro number(NA) g Mass of 8 neutrons = 8/ Avogadro number(NA) g Fraction of mass of water due to neutrons = 8/18 g