Q. How many molecules are present in 1 ml of water..? explain
Here, we know that density of water is 1gm/ml.
Hence, 1 gm water will = 1 ml water.
Now, we have molecular mass of water H2O = 1x2 + 16 = 18 gm
Since, 1 mol water = molecular mass in gm = 18gm.
As no. of molecules = no. of moles x avogadro's no.
And No. of moles = given mass/ molecular mass.
Here, given mass = 1ml= 1gm
Thus, no. of moles of water in 1 ml = 1/18 mol.
And so No. of molecules in 1ml water = no. of moles x avogadro's no. = 1/18 X 6.022 x 1023 =0.33 x 1023 molecules
So, the no. of molecules of water in 1ml of water = 3.3 x 1022
first you have to figure out how many moles of water are in 1 milliliter. Because the density of water is 1g/ml you know that in 1 ml there is 1 gram H2O. To calculate moles you have to know the molar mass (which is 18 g/mol for water). 1 gram / 18 g/mol = .0555 moles water.
Avagadros number is 6.022x10(23) molecules per mole so multiply Avagadros number by the number of moles you have and you got your answer. Here it is 3.34x10(22) molecules of water in 1 mL.