QUESTION 2.31
The depression in freezing point of water observed for the same amount of acetic acid, triehloroacetie acid and trifluoroacctie acid increases in the order given above. Explain briefly.
QUESTION 2.31
The depression in freezing point of water observed for the same amount of acetic acid, triehloroacetie acid and trifluoroacctie acid increases in the order given above. Explain briefly.
The depression in freezing point of a solute in water depends upon the number of particles or ions in its aqueous solution or its degree of dissociation (α). Three acids are arranged in the order of their increasing acidic strengths as follows:
CH3COOH<CCl3COOH<CF3COOH
Fluorine is more electronegative than chlorine. So, trifluoracetic acid is stronger than trichloroacetic acid which in turn stronger than acetic acid. The order of depression in freezing point is also the same. Since fluorine has strongest electron withdrawing inductive effect (-I) effect hence it is the strongest acid.
When strong electron withdrawing groups are attached to the alpha carbon atom of acetic acid the value of degree of dissociation increases and the acid strength also increases. Consequently this increase in acidic strength increases the value of vant Hoff factor (i) and thus there occurs depression in freezing point.
The depression in freezing point of a solute in water depends upon the number of particles or ions in its aqueous solution or its degree of dissociation (α). Three acids are arranged in the order of their increasing acidic strengths as follows:
CH3COOH<CCl3COOH<CF3COOH
Fluorine is more electronegative than chlorine. So, trifluoracetic acid is stronger than trichloroacetic acid which in turn stronger than acetic acid. The order of depression in freezing point is also the same. Since fluorine has strongest electron withdrawing inductive effect (-I) effect hence it is the strongest acid.
When strong electron withdrawing groups are attached to the alpha carbon atom of acetic acid the value of degree of dissociation increases and the acid strength also increases. Consequently this increase in acidic strength increases the value of vant Hoff factor (i) and thus there occurs depression in freezing point.
