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the Laws of Thermodynamics 61. Years ago, a block of ice with a mass of about 20

ID: 1875079 • Letter: T

Question

the Laws of Thermodynamics 61. Years ago, a block of ice with a mass of about 20.0 kg was used daily in a home icebox. The temperature of the ice was 0.0°C when it was delivered. As it melted, how much heat did the block of ice absorb? 62. A 40.0-g sample of chloroform is condensed from a vapor at 61.6°C to a liquid at 61.6°C. It liberates 9870 J of heat. What is the heat of vaporization of chloroform? 63. A 750-kg car moving at 23 m/s brakes to a stop. The brakes contain about 15 kg of iron, which absorbs the energy. What is the increase in temperature of the brakes? 64. How much heat is added to 10.0 g of ice at -20.0°C to convert it to steam at 120.0°C? 65. A 4.2-g lead bullet moving at 275 m/s strikes a steel plate and comes to a stop. If all its kinetic energy is converted to thermal energy and none leaves the bullet, what is its temperature change?

Explanation / Answer

(61)

Given that,

m = 20 kg

T = 0 oC

Heat absorbed by block of ice,

Q = mL

where L = latent heat of fusion = 333.4*103 J/kg

Q = 20 * 333.4*103

Q = 6.67*10^6 J

(62)

Heat liberated by chloroform,

Q = mHv

where, Hv = heat of vapourisation

Hv = 9870 / 40*10^(-3)

Hv = 246750 J / kg