Question

(a) How much energy does it take to heat 250 g of water from 20 ◦C to the boiling point of 100 ◦C? (The specific heat of water is 4190 J/kg · K)

(b) (Suppose you wanted to cause the temperature change in part (a) by using an 800W microwave. If we assume all the power delivered by the microwave goes into the water, how long will it take for the water to change temperature?

(c) The heat of vaporization for water is 22.6×105 J/kg. How much energy is required to completely boil the water after it reaches 100 ◦C? How long does this take in the microwave?

Answer #1

What minimum heat is needed to bring 200 g of water at 40 ∘C to
the boiling point and completely boil it away? The specific heat of
water is 4190 J/(kg⋅K) and its heat of vaporization is 22.6×105
J/kg.

An iron boiler of mass 180 kg contains 770 kg of water at 21 ∘C.
A heater supplies energy at the rate of 58,000 kJ/h. The specific
heat of iron is 450 J/kg⋅C∘, the specific heat of water is 4186
J/kg⋅C∘, the heat of vaporization of water is 2260 kJ/kg⋅C∘. Assume
that before the water reaches the boiling point, all the heat
energy goes into raising the temperature of the iron or the steam,
and none goes to the vaporization...

An iron boiler of mass 180 kg contains 850 kg of water at 23 ∘C.
A heater supplies energy at the rate of 58,000 kJ/h. The specific
heat of iron is 450 J/kg⋅C∘, the specific heat of water is 4186
J/kg⋅C∘, the heat of vaporization of water is 2260 kJ/kg⋅C∘. Assume
that before the water reaches the boiling point, all the heat
energy goes into raising the temperature of the iron or the steam,
and none goes to the vaporization...

An iron boiler of mass 180 kg contains 790 kgof water at 21 ∘C.
A heater supplies energy at the rate of 58,000 kJ/h. The specific
heat of iron is 450 J/kg⋅C∘, the specific heat of water is 4186
J/kg⋅C∘, the heat of vaporization of water is 2260 kJ/kg⋅C∘. Assume
that before the water reaches the boiling point, all the heat
energy goes into raising the temperature of the iron or the steam,
and none goes to the vaporization of...

An iron boiler of mass 180 kg contains 770 kg of water at 21 ∘C.
A heater supplies energy at the rate of 58,000 kJ/h. The specific
heat of iron is 450 J/kg⋅C∘, the specific heat of water is 4186
J/kg⋅C∘, the heat of vaporization of water is 2260 kJ/kg⋅C∘. Assume
that before the water reaches the boiling point, all the heat
energy goes into raising the temperature of the iron or the steam,
and none goes to the vaporization...

An iron boiler of mass 180 kg contains 690 kg of water at 23 ∘C.
A heater supplies energy at the rate of 58,000 kJ/h. The specific
heat of iron is 450 J/kg⋅C∘, the specific heat of water is 4186
J/kg⋅C∘, the heat of vaporization of water is 2260 kJ/kg⋅C∘. Assume
that before the water reaches the boiling point, all the heat
energy goes into raising the temperature of the iron or the steam,
and none goes to the vaporization...

An iron boiler of mass 180 kg contains 830 kg of water at 11 ∘C.
A heater supplies energy at the rate of 58,000 kJ/h. The specific
heat of iron is 450 J/kg⋅C∘, the specific heat of water is 4186
J/kg⋅C∘, the heat of vaporization of water is 2260 kJ/kg⋅C∘. Assume
that before the water reaches the boiling point, all the heat
energy goes into raising the temperature of the iron or the steam,
and none goes to the vaporization...

(a) How much energy is needed to raise 1.00 kg of liquid water
from 19.9 ?C to 99.9 ?C? (b) How much energy is needed to evaporate
1.00 kg of liquid water (at 100?C) into steam (at 100?C)? Be
careful not to confuse J with kJ. (c) Is the relative size of these
two numbers consistent with everyday experience that it takes much
longer (e.g. maybe an hour or so) to boil away an entire pot of
water than it...

How much energy does it take to completely vaporize a cow?
Assume that since a cow is mostly water, the thermodynamic
properties of water will do in place of the cow. Water has a
specific heat of 4187 J / (kg • K), a latent heat of vaporization
of 2256 kJ / kg, and a boiling point of 373 K. A cow has a mass of
650 kg and a body temperature of 311 K.

At 1 bar, how much energy is required to heat 69.0 g of H2O(s)
at –24.0 °C to H2O(g) at 163.0 °C?
STRATEGY: 1. Calculate the energy needed for each temperature
change or phase change individually. a. the energy needed to heat
69.0 g of H2O(s) from –24.0 °C to its melting point. b. the energy
needed to melt 69.0 g of H2O(s) at its melting point. c. the energy
needed to heat 69.0 g of H2O(l) from the melting...

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