An automobile engine provides 519 Joules of work to push the pistons.In this process the internal energy changes by -2729 Joules.What is q for the engine? This represents the amount of heat that must be carried away by the cooling system.

Determine whether the statements given below are true or false. Consider an endothermic process taking place in a beaker at room temperature. (a) Heat flows from the surroundings to the system. (b) The beaker is cold to the touch. (c) The pressure of the system decreases. (d) The value of q for the system is positive.

9.89 A sample of gas is 80.0% CH4 and 20.0% C2H6 by mass. What is the heat from the combustion of 1.00 g of this mixture? Assume the products are CO2 (g) and H2O (l).

9.31 A metal radiator is made from 26.0 kg of iron. The specific heat of iron is 0.449Jg1C1 . How much heat must be supplied to the radiator to raise its temperature from 25.0 to 5 5.0°C?

9.58 For the reaction C2H2(g)+2H2(g)C2H6,H=136 kJ. What are the ratios that can be defined between moles of substances and energy?

The second law of thermodynamics is sometimes paraphrased as: you can't break even. Explain. Because energy cannot be created out of nothing. Because some energy is lost in all energy transactions. Because some energy is gained in all energy transactons.

Describe the interconversions of potential and kinetic energy in a moving pendulum. A moving pendulum eventually comes to rest. Has the energy been lost? If not, what has happened to it?

An exothermic reaction is carried out in a coffee-cup calorimeter. Which of the following statements is/are NOT true for the process? (a) The temperature of the water increases. (b) Heat is absorbed by the water. (c) The enthalpy of the products is higher than the enthalpy of the reactants. (d) qH2o=qrxn (e) qrxn0 (f) qrxn+qH2o=0

Hydrogen is an ideal fuel in many respects; for example, the product of its combustion, water, is nonpolluting. The heat given off in burning hydrogen to gaseous water is 5.16 104 Btu per pound. What is this heat energy in joules per gram? (1 Btu = 252 cal; see also Table 1.4.)

Enthalpy a A 100.-g sample of water is placed in an insulated container and allowed to come to room temperature at 21C. To heat the water sample to 41C, how much heat must you add to it? b Consider the hypothetical reaction,2X(aq)+Y(l)X2Y(aq)being run in an insulated container that contains 100. g of solution. If the temperature of the solution changes from 21C to 31C, how much heat does the chemical reaction produce? How does this answer compare with that in part a? (You can assume that this solution is so dilute that it has the same heat capacity as pure water.) c If you wanted the temperature of 100. g of this solution to increase from 21C to 51C, how much heat would you have to add to it? (Try to answer this question without using a formula.) d If you had added 0.02 mol of X and 0.01 mol of Y to form the solution in part b, how many moles of X and Y would you need to bring about the temperature change described in part c. e Judging on the basis of your answers so far, what is the enthalpy of the reaction 2X(aq) + Y(l) X2Y(aq)?