Explanation:
i.e M = m/V(L)
M= Molarity of substance
m = number of moles of substance (i.e solute)
V(L) = volume of solution in Litres
So talking about our question molarity should be 0.5 M,volume should be 0.1 L , and we should know that Molar Mass of NaOH is 40 because Atomic mass of Sodium i.e (Na known as Natrium) is 23,Atomic mass of Oxygen (O) is 16 and Atomic mass of Hydrogen is 1.
Adding them all up gives Molecular mass of NaOH as 40
So if we solve above equation we get no of moles of NaOH present in 0.1 litres of solution
Let’s do that math
Rearranging equation we get m=M×V(L) i.e m= 0.5×0.1 =0.05. So 0.05 moles of NaOH are present in 100 ml of 0.5 Molar solution
Now we also know that to find no of moles of a substance we have a formula and it is m=W/Mw where
m = no of moles of a substance
W = Mass of substance
Mw = Molecular weight of the substance
So substituting all values and rearranging equation we get mass of NaOH as
W=m×Mw = 0.05×40=2 grams
Hence we found the required mass of NaOH as 2 grams.
Now talking about shortcut
we know as explained above M=m/V(L) and m=W/M
Substituting value of m(no of moles) in M=m/V(L) we get M=WMw×V(L)
Try substituting the values yourself and get the answer
Note :: The value of Volume should always be substituted in terms of Litre only. That is the reason i used the letter (L) at all the places with V
So thats all get the answer and comment any other problems below
Hope you got your problem solved
Thanks!!!
