Question

What is the mass of oxygen present in 18ml of water

Answer 1

Answer:

18 gram is also the weight of one mole of water. Now, as we know, one mole of any substance contains Avagadro number of particles of that substance. So, 18 ml of water contains 6.023 x 10^23 number of molecules.

Answer 2

Answer:

0.128 grams

Explanation:

Given: Volume of water = 18ml

To find: Mass of $O_{2}$ present in 18ml of water

We know that water contains Hydrogen and Oxygen in a 2:1 ratio by volume ($H_2O$)

So, the volume of oxygen present in 18ml of water = 18ml.

Now,

The volume of 1-mole Oxygen gas = 22400 mL

So, the volume of x mole oxygen gas = 18 mL

Hence, $x=\frac{18}{22400}=0.000803$ moles.

Now, the mass of 1 mole Oxygen = 16g

Mass of 0.00803 moles Oxygen = 16*0.00803g = 0.128 grams

So, the answer is 0.128 grams.