a) How much heat is required to raise temperature of 250 mL of water from 20.0 oC to 35.0 oC? (b) How much heat is lost by the water as it cools back down to 20.0 oC?

A pond in winter has a layer of ice 5cm thick. The temperature of the air above the ice is -10C and the temperature of the water directly below the ice is 0C. (i) Find out how much heat passes by conduction through a square meter of ice each second (thermal conductivity of ice = k_ice = 2.2 W/m C) (ii) How would the amount of heat transfer differ if the ice were 7.5 cm thick instead of 5 cm thick? (how many times as much or as less)

An ice bag containing 0°C ice is much more effective in absorbing heat than one containing the same amount of 0°C water.   (a) How much heat (in J) is required to raise the temperature of 0.900 kg of water from 0°C to 25.0°C?   (b) How much heat (in J) is required to first melt 0.900 kg of 0°C ice and then raise its temperature?   (c) Explain how your answers support the contention that the ice is more effective.

How many grams of coffee must evaporate from 700 g of coffee in a 190 g glass cup to cool the coffee and the cup from 95.0°C to 24.0°C? Assume the coffee has the same thermal properties as water and that the average heat of vaporization is 2,340 kJ/kg (560 cal/g). Neglect heat losses through processes other than evaporation, as well as the change in mass of the coffee as it cools. g Do the latter two assumptions cause your answer to be higher or lower than the true answer? O My answer is lower than the true answer because, if coffee loses heat in other ways and its mass decreases, it will need more evaporation for the same temperature drop. O My answer is higher than the true answer because, if coffee loses heat in other ways and its mass decreases, it will need less evaporation for the same temperature drop. O My answer is higher than the true answer because, if coffee loses heat in other ways and its mass decreases, it will need more evaporation for the same temperature drop. O My…