Use the following information on Cr to determine the amounts of heat for the three heating steps required to convert 199.1 g of solid Cr at 1760°C into liquid Cr at 2060°C. mp = 1860°C bp = 2672°C Enter in kJ

The cooling effect of alcohol on the skin is due to its evaporation. Calculate the heat of vaporization of ethanol (ethyl alcohol), C2H5OH. C2H5OH(l)C2H5OH(g);H=? The standard enthalpy of formation of C2H5OH(l) is 277.7 kJ/mol and that of C2H5OH(g) is 235.1 kJ/mol.

Equal masses of liquid A, initially at 100C, and liquid B, initially at 50C, are combined in an insulated container. The final temperature of the mixture is 80C. All the heat flow occurs between the two liquids. The two liquids do not react with each other. Is the specific heat of liquid A larger than, equal to, or smaller than the specific heat of liquid B?

Evaporation of sweat requires energy and thus take excess heat away from the body. Some of the water that you drink may eventually be converted into sweat and evaporate. If you drink a 20-ounce bottle of water that had been in the refrigerator at 3.8 C, how much heat is needed to convert all of that water into sweat and then to vapor? (Note: Your body temperature is 36.6 oc. For the purpose of solving this problem, assume that the thermal properties of sweat are the same as for water.)

On a hot day, you take a six-pack ot a on a pcmc, cooling it with ice. Each empty (aluminum) can weighs 12.5 g. A can contains 12.0 oz of soda. The specific heat of aluminum is 0.902 J/g C; take that of soda to be 4.10 J/g C. (a) How much heat must be absorbed from the six-pack to lower the temperature from 25.00 to 5.00C? (b) How much ice must be melted to absorb this amount of heat? (Hfus of ice is given in Table 8.2.)

Melting lead requires 5.50 cal/g. Calculate how many joules are required to melt 1.00 lb (454 g) lead.

The amount of heat required to melt 2 lbs of ice is twice the amount of heat required to melt 1 lb of ice. Is this observation a macroscopic or microscopic description of chemical behavior? Explain your answer.

Are changes in state physical or chemical changes? Explain. What type of forces must be overcome to melt or vaporize a substance (are these forces intramolecular or intermolecular)? Define the molar heat of fusion and molar heat of vaporization. Why is the molar heat of vaporization of water so much larger than its molar heat of fusion? Why does the boiling point of a liquid vary with altitude?