Respuesta :
Answer: 0.040 mol glycerin > 0.030 mol KBr> 0.025 mol [tex]Na2SO_4[/tex]
Explanation:
Depression in freezing point:
[tex]T_f^0-T_f=i\times k_b\times m[/tex]
where,
[tex]T_f[/tex] = freezing point of solution
[tex]T^o_f[/tex] = freezing point of solvent
[tex]k_b[/tex] = freezing point constant
m = molality
1. For 0.040 mol glycerin
, i= 1 as it is a non electrolyte and does not dissociate, concentration of ions will be [tex]1\times 0.040=0.040[/tex]
2. For 0.025 mol [tex]Na2SO_4[/tex]
[tex]Na_2SO_4\rightarrow 2Na^++SO_4^{2-}[/tex]
, i= 3 as it is a electrolyte and dissociate to give 3 ions. and concentration of ions will be [tex]3\times 0.025=0.075[/tex]
3. For 0.030 mol KBr
, i= 2 as it is a electrolyte and dissociate to give 2 ions, concentration of ions will be [tex]2\times 0.030=0.060[/tex]
Thus as concentration of solute is highest for [tex]Na_2SO_4[/tex] , the depression in freezing point will be highest and thus freezing point will be lowest.
The order of decreasing freezing point: 0.040 mol glycerin > 0.030 mol KBr> 0.025 mol [tex]Na2SO_4[/tex]
