Question

calculate the change in heat in joules for condensation of 7.90g of steam at 100*Celcius

Answer 1

Solution:- Here the condensation is taking place of 100 degree C steam. It means It's a phase change where 100 degree C steam is changing to 100 degree C water.

100 degree C steam <------> 100 degree C water + heat

q = m*delta H_vap

where, q is the heat energy, m is mass and delta Hvap is the enthalpy of vaporization.

enthalpy of vaporization for water is 2257 J/g.

on plugging in the values..

q = 7.90 g x 2257 J/g

q = 17830.3 J

let's round this to three sig figs since the given mass has three sig figs.

So, tthe answer would be 1.78 x 10⁴ J. The sign would be negative since the heat goues out in condensation process.