Question

Why is ice at $273K$ more effective in cooling than water at the same temperature?

Answer 1

Cooling takes place when heat is removed. In the case of ice at $273K$ ($0^{0}C$), it will first take the heat (the latent heat of melting) to convert itself into the water at $273K$ Whereas, water at $273K$ will absorb heat lesser than the latent heat of melting of ice and also its phase won't change until the temperature reaches $373K$ (${100}^{0}C$).

So, at the same temperature of $273K$, a large amount of heat will be removed by ice from the surroundings than in the case of water. Hence, ice at $273K$ is more effective in cooling than water at the same temperature.