Question

calculate the amount of energy required to convert saturated water at 150 kpa to superheated steam at 180 C and at the same pressure.

Answer 1

As there is no mention of amout of Water I would assume it as 1 gm

And temperture of the saturated water = 25⁰ = 298 K

SO

Okay, we first need to calculate the amount of heat energy required to raise the temperature of water to its boiling point(100°C) using the formula Q= mcθ where Q is the amount of heat energy required, m is the mass of the sample of water, c is the specific heat capacity of water and θ is the change in temperature.

Q= (1)(0.999043976)(100-25)
= 74.92 cal

We now need to calculate the amount of heat energy required to convert the sample of water to steam at its boiling point using the formula Q= mL where Q is the amount of heat energy required, m is the mass of the sample of water and L is the latent heat of vapourisation of water.

Q= (1)(540)
= 540 cal

Now, we shall calculate the amount of heat energy required to raise the temperature of the steam to 180°C using the formula Q= mcθ.

Q= (1(0.485)(180-100)
= 38.8 cal

Finally, we add up the amount of heat energy required at each of the three stages to determine the net amount of heat energy required, Q

Q= (74.92)+(540)+(38.8)
= 653.72 cal

correct to 2 significant figures.