Answer:
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= (20.0)(0.999043976)(100-25)
= 1.498565965x10³ 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= (20.0)(540)
= 1.08x10⁴ cal
Now, we shall calculate the amount of heat energy required to raise the temperature of the steam to 150°C using the formula Q= mcθ.
Q= (20.0)(0.485)(150-100)
= 485 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, Qₙ.
Qₙ= (1.498565965x10³)+(1.08x10⁴)+(485)
= 1.278356597x10⁴ cal
= 1.28x10⁴ cal correct to 3 significant figures.
