Question

A high-end gas stove usually has at least one burner rated at 14,000 Btu/h.

(a) If you place a 0.21-kg aluminum pot containing 2.7 liters of water at 20°C on this burner, how long will it take to bring the water to a boil, assuming all the heat from the burner goes into the pot?
________ min

(b) Once boiling begins, how much time is required to boil all the water out of the pot?
_______min

Answer 1

sol:

mass(m) = 0.21kg

The total thermal energy going into the pot and the water to bring the water to a boil may be stated as:

we know that the time taken to raise the water to a boil is:

where P = power

Q= mcΔT

c= specified heat (for copper its 387J/kg∙°C and for water, 4186J/kg∙°C)

m = mass

T = temperature

  The mass of the water is 2.7kg (easy conversion from liters).

• The power is :

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From part (a)

(b) In this case, the water changes phase, so for water, use the equation Q = mL (where L is the latent heat of vaporization, water’s is 2.26 x 10^6J/kg). :