Question

A glucose solution having strength of 18 g/L is isotonic with an aqueous NaCl solution. The strength of NaCl (in g/L) is
a.1.35
b.2.93
c 5.85
d 8.4​

Answer 1

molarity = weight/molar mass× volume of solution (lit) ,. here weight/volume is strength so we put the value of strength of glucose solution then molarity= 18/ 180, here 180 is molar mass of glucose then molarity is 0.1 and NaCl solution and glucose solution is isotonic means their molarity is equal to each other molarity of NaCl is also 0.1 , molarity (NaCl)=solution strength/molar mass , 0.1= solution strength/58.5 then solution strength of NaCl is 5.85 ans

Answer 2

Given : A glucose solution having strength of 18g/L is isotonic with an aqueous NaCl solution.

To find : The strength of NaCl in g/L

solution : for isotonic solution,

osmotic pressure of glucose = osmotic pressure of NaCl

⇒C₁RT = C₂RT

⇒C₁ = C₂

⇒S₁/M₁ = S₂/M₂

here, S₁ = 18g/L , M₁ = 180 g/mol , M₂ = 58.5 g/mol

so, 18/180 = S₂/58.5

⇒S₂ = 5.85 g/L

Therefore the strength of NaCl is 5.85 g/L