Posted by lisa on .
In a 100g sample of water, determine the amount of weight that
is attributed to Hydrogen and to Oxygen.
i found the mass ratio which is 2:16 & then reduced its 1:8. then i set up my equation.
1x+8x=100g
9x=100g
x=11.11111111 or 100/9 then i have to substitute. 1(100/9)= 11.11111111g or 100/9g. & 8(100/9) =88.88888889g or 800/9g. is this right ?

Chemistry 
sehajnoor,
1 mole of water requires 1 mole of hydrogen (H2) and 0.5 moles of oxygen (O2).
The molar mass of water is 100/18
This requires 100/18 moles of hydrogen. As the molar mass of hydrogen is 2, it requires 200/18 = 100/9 g of hydrogen.
It requires 0.5*100/18 mole of oxygen. The molar mass of oxygen is 32. The mass of oxygen required is 800/9 g
It requires 100/9 g of hydrogen gas and 800/9 g of oxygen gas to make 100 g of water.