Answer
mass of 1 mole = 18g
mass of 1 mL = 1g
the unit used is gram
Explanation:
There are two ways to find mass of water:
1st way:
If we find Mass of water for one mole of water:
For this purpose we use mole formula as below
no. of moles = mass in grams / molar mass
if we find mass for one mole of water:
then
no. of moles of water = 1 mol
molar mass of water = H₂O = (1x2 +1x16) = 18 g/mol
mass of water = ?
Put the value in the mole formula
no. of moles = mass in grams / molar mass . . . . . . . . . . . . (1)
by rearranging the formula (1)
mass in grams = no. of moles x molar mass
mass in grams = 1 mole x 18 g/mol
mass in grams = 18 g
So for one mole of water the mass of water is 18 g and the unit for it is gram.
2nd way:
We can find mass of water by another way too
if we find the mass 1 mL of water
then the formula will be used is
D = m/v
where D is density
m is the mass
and v is the volume
So
density of water for 1 mL (D) = 1 g/ml
volume of water = 1 mL
mass of water = ?
By Rearranging density formula for mass
m = D/v ......................... (2)
put the values in equation 2
m= 1gmL⁻¹ / 1 mL
m= 1g
So the mass of 1mL is 1g
