Carbonyl stretching frequency of aliphatic carboxylic acids

1.) Carbonyl stretching frequency of aliphatic carboxylic acids in dilute solution is located near 1770/cm. This frequency is much higher than the carbonyl frequency of these substances when measured neat (1720/cm). Also it is considerably higher than the corresponding aliphatic ester (1745/cm) value. Explain

2.) The antisymmetric -CH2-CO-O- stretching vibration in carboxylic acids is heavily mixed with the in-plane bending mode of the O-H group. In alcohols two vibrations seldom show evidence of mechanical coupling. Explain.