Density of water at room temperature is 1g/ml. How many molecules are there in a drop of water if its volume is 0.05 ml?
Answers
1.68 x 10^21 Molecules
Given:
Volume of drop of water = 0.05 mL
Density of water at room temperature = 1 g/ml
To Find:
Amount of molecules that is there in a drop of water.
Calculating:
Formula used to calculate the mass of drop of water
= Volume x Density
Calculating the mass of water by substituting the values known to us in this formula:
= 0.05 ml x 1 g/ml
= 0.05 grams
Calculating the molecular mass of water:
(H2O)
= 1 x 2 + 16 x 1
= 2 + 16
= 18 grams
1 mole of water is equal to 18 grams
By knowing this we can tell for 0.05 grams of water:
= 1 mol / 18 grams x 0.05 grams
= 0.0028 mol
Calculating the number of molecules present:
1 mole = 6.022 x 10^23
From this we can get to know number of molecules 0.0028 moles of water contain:
= 6.022 x 10^23 x 0.0028
= 1.68 x 10^21 molecules
Therefore, there are 1.68 x 10^21 molecules in a drop of water if its volume is 0.05 mL.