Falling Behind in Studies? Join Our Performance Improvement Batch. Enroll For Free
One of our academic counsellors will contact you within 1 working day.
Click to Chat
1800-1023-196
+91-120-4616500
CART 0
Use Coupon: CART20 and get 20% off on all online Study Material
Welcome User
OR
LOGIN
Complete Your Registration (Step 2 of 2 )
A sample of drinking water was found to be severely contaminated with Chloroform, CHCl3 . The level of contamination was 15 ppm(by mass). (i) Express this in percent by mass. (ii) Determine the molality of chloroform in water.
1) 15 ppm means 15 parts in 1 millions (10^6) and percentage always for 100 hence 15 ppm = (15/10^6 )*100 = 15*10^-4 = 1.5*10^-32) molar mass of chloroform = 118.5g/ mol from percentage by mass 100 gram of sample has 1.5*10^-3 g of chloroformthen 1000 gram of sample has = 1.5*10^-3 g * 1000 gram/ 100 gram = 1.5*10^-2 gmolality = moles of solute / mass of solvent in Kg moles of solute = mass of solute / molar mass = 1.5*10^-2/ 118.5 =1.266*10^-4 molesmolality = 1.266*10^-4 moles/ 1 Kg =1.266*10^-4 m Thanks & RegardsRinkoo GuptaAskIITians faculty
1).Converting 15ppm in percent by mass-15ppm means 15 parts in 1 million(106)and % means 100so, 15 ppm = 15 * 102/106= 1.5 * 10-32).For Molality-Molality = Moles of solute/Mass of solvent in Kgnow,100gm of sample contains 1.5 * 10-3 of CHCl3therefore, 1000gm will contains = 1.5 * 10-3 * 1000/100= 1.5.* 10-2gMoles of solute is given as = Mass/Molar mass= 1.5 *10-2/118.5 ( 118.5 Molar mass of CHCl3)moles = 1.266 * 10-4 molesThus molality = 1.266 * 10-4/1 Kg= 1.266 * 10-4mThanks & RegardsAarti Guptaaskiitians Faculty
Here, ppm = parts per million = 15. Using %w/w = ppm x 10^-4, %w/w = 15/10000 = 0.0015 % Now take 1 million gm soln. Wt. solute = 15 g. This means moles of solute = 15/120(approx) = 0.125 mol. Now wt. of solvent is approx. 10^6 gm. Molality = moles of solute x 1000 / wt solvent in gm = 0.125/1000 =0.000125 m or 1.25 x 10^-3 m
15 ppm = 15/ 10^6(As 15 ppm means 15 parts in 1 million)I) percentage means 100Mass % = 15*100/10^6 =1.5*10^-32) 100g contains 1.5*10^-3Then 1000g will contain 1.5*10^-2Moles = 1.5*10^-2/119.5 = 1.2*10^-4Molality = 1.2*10^-4/ 1kg =1.2*10^-4 molar
Hello students,The solution is as follows1).Converting 15 ppm in percent by mass-15 ppm means 15 parts in 1 million(10^6) and % means 100so, 15 ppm = 15 * 10^2/10^6= 1.5 * 10^-32).For Molality-Molality = Moles of solute/Mass of solvent in Kgnow, 100gm of sample contains 1.5 * 10-3 of CHCl3therefore, 1000gm will contains = 1.5 * 10-3 * 1000/100 = 1.5.* 10-2gMoles of solute = Mass / Molar mass= 1.5 * 10^-2 / 118.5 ( 118.5 Molar mass of CHCl3)moles = 1.266 * 10^-4 molesThus molality = 1.266 * 10^-4/1 Kg= 1.266 * 10^-4mIhope the avove solution will solve all your doubts.ThanksAll the best for your exams.
Post Question
Dear , Preparing for entrance exams? Register yourself for the free demo class from askiitians.
points won -