CORRESPONDENCE PROBLEM FORM FOR INDEPENDENT STUDY To the Editor DEARSIR: Several years ago I began an intensive study of physical chemistry. Realizing that reading alone was not suficient, I started to work a number of problems. These I did on scrap paper, throwing them away when completed. Then, realizing that this work was lost for future reference, I designed a form (letter size, punchedfor standard looseleaf cover) on which to work problems. This I had printed. A worked problem on this form is enclosed, the problem being of my own construction. This printed form was designed to meet the following requirements : One problem to a form. Title and author of book from which problem is taken, page on which found, and problem number. A complete and identical copy of problem as given. The author's answer to problem, if any. Laws used to solve problem, with formulas. Necessary data not given in problem. The calculations made in proper order. The errors which are natural to the laws used and to the method of solution. My answer, the number of mathematical operations, and the nnmber of mistakes made. Yours truly, CLAIRC. RAUSCH 2947 BEWICKAVENUE DEmorT. MICFLIGAN
PllOBLEMS IN PHYSICAL CHEMISTRY CLAlR C. RAUSCH
Date Feb. 18.11131 TYPE Oamotio P r e s a u m Problem. souree Bq C l a i r C. RB~aoh Let.= ..rtr.
.. b. r. etr.
PROBLEM No. -5 PN-
A n h v s i o l o ~ i o a ls a l t s o l u t i o n is made by d i s a o l v i n n 8.5 aram of aacl i n A o h s lit& of d i s t i l l e d water. hi. s b l u t i o n is i a o t o n i o t o t h e blood. t h a t is. it haa t h e same osmotic pressure. Caloulate t h o osmotio p r e s s u r e of t h e blood. aseuming t h a t t h e NaCl is 855 ioniaed. ~ o d ytemperature is 98.69. Express y o u ~answer i n atmosphere8 end i n pounds p e r square inoh.
Answer. source 6.84; 100.6 Mine. 6-84 : 100.6 Difference. Laws used : - ~ i u ~fe7m~!.s. The l a w of Charles: Volume being oonatant. t h e p r e s s u r e of a n i d e a l gss i a d i r e o t l y p r o p o r t i o n a l t o i t s a b s o l u t e temperature. Van't Hoff's Hypothesis: Dissolved substancae a c t a s P:P::T:T. though t h e y r e r e g a s e s occupying t h e same a p o a . The osmotic p r e s s n r e e x e r t e d by a substance i n s o l u t i o n is equal t o t h e g a s p r e s a u m whioh it would e x e r t if I t were a g a s oooupying t h e same volume a s t h a t of t h e solvent. Necessary data and assumptions: Om mol of a n o n - e l e c t r o l y t e when d i s a a l v e d i n 22.4 l i t e r a of w a t e r a t OOC. w i l l have a n oamotio p r e s s u r e of one stmoaphem, 01. when r e 22.4 d i s s o l v e d i n one l i t e r a t O°C. w i l l have a n osmotio ~ ~ s s s u ai atmosphsraa. One atmosphere of p r e s s u r e e q u a l s 14.7 pounds p e r square inoh. The atom10 wei h t of eodium is ila 22.997. of o h l o r i n e C 1 85.457. OW. i s 2730A. 00. = $9. 32)/1.8. one mol of a n ionogsn g i v e s one p l u s f r a o t i o n ionized mols of d i s c r e t e p r t l o l e s .
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x :25.436 atmoapherea. t h e p r a e s n r s of a g a s of constant volume a t body temperature. Oamotio nreaaure e o u a l s t h e u r e s s u r e of a aas of conatant-volume s t ' b o d y temp&atula t i m s one p l u s t h e f r a o t i o n of NaC1 ionized times t h e grams o f NaCl d i s s o l v e d divided by t h e molecular weight o f sodium chloride. 08mot10 Dresson = 25.436 x 1.85 r 8.6 = 6.8429
Answer 6.8429: 100.59 merationa 71 Mistakes 1 Errors: S o l u t i o n is i n e r r o r i n s o f a r a s a o t u a l g a s e s o r a c l n t i o n a d e v i a t e f r o m t h e i d e a l a a s l a r e u w n r h i o h t h e e o l u t i o n of t h l s Any addenda on other side. b b l e m is-based.
