Question

Ive been trying to figure this question out for a couple days, need some clues!

.15M NaCL solution is isotonic with blood. In which of the following solutions will the cell lose fluid and shrink?

a. 0.15M KBr
b. 0.15M glucose
c. 0.15M KNO3
d. 0.15M K2SO4
e. 0.15 M NH4CL

The correct answer is D. but how??

Answer 1

what difference in these compounds do you find can you tell hen they ionize in water

Answer 2

0.15M K2SO4
0.15M KBr
Let me give you clue
out of these two solution which solution has high amount of K+ ions can you answer now

Answer 3

but not all of them have K+ ions?

Answer 4

whatever but the charge and ions are one right

Answer 5

would i have to just figure out the moles?

Answer 6

yes

Answer 7

yaa ur right i think

Answer 8

isnt molarity Moles/1L?
so then since they are all 0.15 it means there isnt a difference in moles?

Answer 9

thats what i am saying along with the moles it also depends upon the no of particles dissociated

u use the following equation of osmotic pressure
Π = i × (MRT)
i= no of ions dissociated
and M = Molarity
RT u keep constant
only for K2 So4 u find different osmotic pressure mean different concentration

Answer 10

for example 0.15 KBr --->K+ + Br-
Π = 0.15*1* RT
=0.15RT

for KNO3----->K+ +NO3-
Π = 0.15 * 1 * RT
=0.15RT

for 0.15 M K2SO4 ----> 2K+ +SO4-2
Π =0.15 * 2 *RT
=0.3RT

Answer 11

are u getting the stuff here

Answer 12

the shrinkage will happen only when there id difference in osmotic pressure right
in the above case K2SO4 has different osmotic pressure than the other members hence addition of this will shrink the cell

Answer 13

how do you calculate that for glucose though?

Answer 14

good question u have to consider it as one particle or molecule since it cant dissociate

Answer 15

as glucose dissolves without ionizing, each
mole of glucose produces one mole of dissolved particles)

Answer 16

ohh i understand now!
thankyou so much!

Answer 17

you are welcome :)
at last you figured it out thank god
:)say thank you to OS.