Answer to Question #139068 in Inorganic Chemistry for chi

Question #139068
A sample of caustic soda weighing 1.675 g was found to contain 97.25% of total alkali calculated as NaOH and of which is 2.48% was Na2CO3. What volume of 1.15 N acid could have been consumed in the Polypropylene and MO titrations as ordinarily performed?

MW: NaOH = 40.0, Na2CO3 = 106.0
Expert's answer

(Assuming that 1.15 N actually means 1.15 M HCl acid, Polypropylene was meant to be Phenolphthalein indicator and MO is Methyl Orange indicator.)

Mass of NaOH "=\\dfrac{97.25}{100}x1.475 = 1.4344375g"

Mass of Na2CO3"\\dfrac{2.48}{100}x1.475 = 0.03658g"

Moles of NaOH "=\\dfrac{1.4344375}{40} = 0.03586mol"

Moles of Na2CO3"=\\dfrac{0.03658}{106} = 3.383x10^-4mol"

Moles of acid required to react with all the NaOH

Mole ratio=1:1

Hence moles of acid "=\\dfrac{1}{1}x0.03586 = 0.03586 mol"

Moles of acid required to react with all Na2CO3

Mole ratio = 2:1

Hence moles of acid"=\\dfrac{1}{2}x3.383x10^-4 = 1.692x10^-4 mol"

Total moles of acid used = 0.03586 + 1.692x10^-4 = 0.03602915mol.

Volume of acid"=\\dfrac{moles x 1000}{molarity} = \\dfrac{0.0360291x1000}{1.15}"

= 31.33 cm3 for Phenolphthalein

For MO"=\\dfrac{31.33}{100} = 0.3133" cm3

Need a fast expert's response?

Submit order

and get a quick answer at the best price

for any assignment or question with DETAILED EXPLANATIONS!


No comments. Be the first!

Leave a comment

New on Blog