Question

Lauc GENERAL CHEMISTRY GROUP STUDY SE The first 3 problems are to be submitted today. #1.(30pts, 15 pts each) (i) Consider a 100 meter high waterfall. If the decrease in potential energy of the water (.e., mgh) is totally converted into heat, calculate the temperature difference between the top and bottom of the waterfall. Data: m= mass, g = acceleration due to gravity = 9.81 m/s". The specific heat of water = 4.184 J/(g°C). () If a system absorbs 23.0 J of heat from the surroundings, and if it also decreases its internal energy by 27 J, compute the work (w) associated with this process, Interpret the sign of your answer.

Answer 1

1) Heat will come from potential energy. Thus;

Potential energy = Heat

m * g * h = m * s * Delta T

g * h = s * Delta T

9.81 * 100 = 4.184 * Delta T

Delta T = 234.46 ° C .....Answer

2) System absorbs heat and hence positive i.e. Q = 23 J

Decrease in internal energy = E = - 27 J

Work done ( W) = ?

E = Q + W

W = E - Q = -27 - 23 = - 50 J ....Answer

Negative sign shows system does 50 J work on surroundings.