Grade 12Physical Chemistry

20 g of impure NaCl solution is added to aqueous solution having excess AgNO3. AgCl precipitation is obtained with mass 28.7g. find % purity of NaCl.

vindhya

10 Years agoGrade 12

8 Answers

abhishek kumar

10 Years ago

i think it should be 20 percent

vindhya

10 Years ago

how, can you please tell me.

akash

Approved Tutor Answer10 Years ago

as 0.2 moles of agcl is produced it means Chlorine obtained from nacl was also 0.2 moles. this implies 0.2 moles of nacl were present in the impure solution. molesXatomic weight(nacl)= MASS of NaCl present in impure substance.

vindhya

10 Years ago

ya thanks, but the answer i have is 58.8%.

so if anyone can provide a reason for this answer, i'll be really thankful.

still thank you Mr. Akash

akash

10 Years ago

my ans is 58.5. a little error in decimal places does not matters much as in exam options are not kept that close. so 58.5 is correct.

vindhya

10 Years ago

thanks a lot. your answer is approved

abhishek kumar

10 Years ago

sory corect answer is 58.5 you can approach it by writting the balance chemical eqn {1 mol agcl will be produced by one mol of nacl} so 28.7g of agcl ie;0.2 mol will be produced by 0.2 mol of nacl

now 0.2 mol nacl is equal to 11.7 gm of nacl . hence % purity =(11.7/20)*100=58.5%