A hot 111.6 g lump of an unknown substance initially at Substance Specific heat (J/(g.°C)) 150.0 °C is placed in 35.0 mL of water initially at 25.0 °C aluminum 0.897 and the system is allowed to reach thermal equilibrium. The graphite 0.709 final temperature of the system is 60.6 °C. rhodium 0.243 titanium 0.523 Using this information and the specific heat values for tungsten 0.132 zinc 0.388 several metals in the table, identify the unknown substance. Assume no heat is lost to the surroundings. water 4.184

9.83 A student performing a calorimetry experiment combined 100.0 mL of 0.50 M HCl and 100.0 mL of 0.50 M NaOH in a coffee cup calorimeter. Both solutions were initially at 20.0°C, but when the two were mixed, the temperature rose to 23.2°C. (a) Suppose the experiment is repeated in the same calorimeter but this time using 200 mL of 0.50 M HCl and 200.0 mL of 0.50 M NaOH. Will the T observed he greater than, less than, or equal to that in the first experiment, and why? (b) Suppose that the experiment is repeated once again in the same calorimeter, this time using 100 mL of 1.00 M HCl and 100.0 mL of 1.00 M NaOH. Will the T observed he greater than, less than, or equal to that in the first experiment, and why?

A 20.0-g block of iron at 50.0C and a 20.0 g block of aluminum at 45C are placed in contact with each other. Assume that heat is only transferred between the two blocks. a Draw an arrow indicating the heat flow between the blocks. b What is the sign of qsys for the aluminum when the blocks first come into contact? c What will you observe when qsys for the iron is zero? d Estimate the temperature of the Al and Fe blocks when qsys of the iron equals qsys of the aluminum.

Nitric acid, HNO3, can be prepared by the following sequence of reactions: 4NH3(g)+5O2(g)4NO(g)+6H2O(g)2NO(g)+O2(g)2NO2(g)3NO2(g)+H2O(l)2HNO3(l)+NO(g) How much heat is evolved when 1 mol of NH3(g) is converted to HNO3(l)? Assume standard states at 25 C.

The addition of 3.15 g of Ba(OH)28H2O to a solution of 1.52 g of NH4SCN in loo g of water in a calorimeter caused the temperature to fall by 3.1 C. Assuming the specific heat of the solution and products is 4.20 J/g C, calculate the approximate amount of heat absorbed by the reaction, which can be represented by the following equation: Ba(OH)28H2O(s)+2NH4SCN(aq)Ba(SCN)2(aq)+2NH3(aq)+10H2O(l)

The decomposition of ozone, O3, to oxygen, O2, is an exothermic reaction. What is the sign of q? If you were to touch a flask in which ozone is decomposing to oxygen, would you expect the flask to feel warm or cool?

Which of the following processes will lead to a decrease in the internal energy of a system? (1) Energy is transferred as heat to the system; (2) energy is transferred as heat from the system; (3) energy is transferred as work done on the system; or (4) energy is transferred as work done by the system. (a) 1 and 3 (b) 2 and 4 (c) 1 and 4 (d) 2and3

The statement Energycan beneithercreatednor destroyedis sometimes used as an equivalent statement of the first law of thermodynamics. There areinaccuracies to the statement, however. Restate it tomake it less inaccurate.

How much will the temperature of a cup (180 g) of coffee at 95 C be reduced when a 45 g silver spoon (specific heat 0.24 J/g C) at 25 C is placed in the coffee and the two are allowed to reach the same temperature? Assume that the coffee has the same density and specific heat as water.

A student performing a calorimetry experiment combined 100.0 ml. of 0.50 M HCI and 100.0 ml. of 0.50 M NaOH in a StyrofoamTM cup calorimeter. Both solutions were initially at 20.0 C, but when the two were mixed, the temperature rose to 23.2 C (a) Suppose the experiment is repeated in the same calorimeter but this time using 200 mL of 0.50 M HCl and 200.0 ml of 0.50 M NaOH. WIII the AT observed be greater than, less than, or equal to that in the first experiment, and why? (b) Suppose that the experiment is repeated once again in the same calorimeter, this time using 100 mL of 1.00 M HCI and 100.0 ml. of 1.00 M NaOH. Will the T observed be greater than, less than, or equal to that in the first experiment, and why?