Question

How much worse (or better) are your results if you ignore the effect of evaporation to the air by leaving out the mass (LN, evap.) value when calculating Lv?

Answer 1

Talking about it in simple words...

what is evaporation?

THE PROCESS in whice the substance changes its state from liquid to gaseous with the increase in temperature or the PRESSURE.

NOW..

WHAT IS LATENT HEAT OF VAPOURISATION?

When temperature of the water increases in the beaker, the bond between the molecules releases and water starts to get vapourised. And when the temperature reaches 100 degrees, then water starts to boil and temperature will not increase and still, water gets converted into STEAM. This process is called as latent heat of vapourisation.

but if we close the surface, this thing will not happen and temperature will start to increase again.

FORMULA OF LATENT HEAT;

Q=m*L

this equation implies that Q(heat) must be added or removed for an object having mass m to change phases.

hence, it is clear mass and pressure(evaporation) are directly proportional to latent heat of vapourisation.

So ignoring it will affect the process of vapourisation.

INCREASING PRESSURE ULTIMATELY REDUCES THE ENTHALPY OF VAPOURISATION and VICE VERSA.