15.00 g of Compound X with molecular formula C,H10 are burned in a constant-pressure calorimeter containing 10.00 kg of water at 25 °C. The temperature of the water is observed to rise by 16.34 °C. (You may assume all the heat released by the reaction is absorbed by the water, and none by the calorimeter itself.) Calculate the standard heat of formation of Compound X at 25 °C. Be sure your answer has a unit symbol, if necessary, and round it to 3 significant digits.

A quantity of 85.0 mL of 0.600 M HCl is mixed with 85.0 mL of 0.600 M KOH in a constant-pressure  calorimeter. The initial temperature of both solutions is  the same at 17.35°C, and the final temperature of the  mixed solution is 19.02°C. What is the heat capacity of  the calorimeter? Assume that the specific heat of the solutions is the same as that of water and the molar heat of neutralization is −56.2 kJ/mol.

When 6.10 g of urea,(NH2)2CO (g), burns to produce CO2 (g), N2 (g) and H2O (l) 67.8 kJ of heat energy are released in a bomb calorimeter.  What is the energy released in the burning of one mole of urea?  Using this, what is the enthalpy of formation of urea?

A 56.1 g sample of polystyrene, which has a specific heat capacity of 1.880 J-g °C-1 is put into a calorimeter (see sketch at right) that contains 250.0 g of water. The temperature of the water starts off at 24.0 °C. When the temperature of the water stops changing it's 29.8 °C. The pressure remains constant at 1 atm. Calculate the initial temperature of the polystyrene sample. Be sure your answer is rounded to the correct number of significant digits. °C thermometer. insulated container water sample. a calorimeter 區 OU Ar

5.00 × 10−2 mol KOH and an excess of hydrochloric acid are combined in 100.0 mL of water initially at 25.0 °C, leading to a final measured temperature of 31.1 °C. (a) What is the heat flow for the water in the calorimeter, qH2O, in Joules? (b) Assuming the calorimeter constant Ccal = 50.0 J °C , what is the heat flow for the calorimeter, qcal, in Joules? (c) What is the amount of heat given off by the reaction, qrxn, in Joules? (d) What is the molar enthalpy of the neutralization reaction (shown below) as measured in the calorimeter, ∆H◦ rxn in kilojoules per mole? H3O + (aq) + OH– (aq) → 2H2O (l)

2 C,H,0(g) + 50,(8) 4 CO2(g) + 4 H,0(g) Be sure any of your answers that are calculated from measured data are rounded to the correct number of significant digits. Note for advanced students: it's possible the student did not do these experiments sufficiently carefully, and the values you calculate may not exactly match published values for this reaction. exothermic Is this reaction exothermic, endothermic, or neither? endothermic O neither If you said the reaction was exothermic or endothermic, calculate the amount of heat that was released or absorbed by the reaction in the second experiment. kJ kJ Calculate the reaction enthalpy AH, per mole of C,H¸0. rxn mol