Question #203c8

2 Answers
Jan 18, 2018

Understand the defenition of Molarity

Explanation:

Molarity= no of moles / volume of solution(in litres)
Hence here we have 0.5litre of 0.79M NaOH
So no of moles of NaOH in this will be
0.5 * 0.79= 0.395 moles of NaOH
We know one mole of NaOH weighs 40 grams
Multiply this by no of moles to get the actual weight needed
So weight needed = 40*0.395 grams
Hope u find it helpful

Jan 18, 2018

x = 15.8g

Explanation:

molarity = (n)/(volume( L); where n is the number of moles of the solute.

n = x/(mm); where x is the required amount of NaOH and mm is the molar massof NaOH

therefore molarity, M = x/(mm) x 1000/(V(mL))

0.79 = x/40 x 1000/500

x = 0.79 x 20

x = 15.8g