Name: Chemistry
Author: McMurry
ISBN: 9781292336145

Ch.9 - Thermochemistry: Chemical Energy

뒤로

모든 교과서

McMurry 8th Edition

Ch.9 - Thermochemistry: Chemical Energy

문제 2

A room-temperature balloon filled with air is placed in the freezer and the balloon contracts. What is the sign of q and w for the air inside the balloon? (LO 9.4) (a) q = +, w = - (b) q = +, w = + (c) q = -, w = - (d) q = -, w = +

문제 4

For which of the following reactions are ΔE and ΔH equal? (a) CO2(g) + H2O(l) → H2CO (b) 2 NaHCO3 (s) → Na2CO3(s) + H2O(g) + CO2(g) (c) 2 H2(g) + O2(g) → 2 H2O(g) (d) CH4(g) + 2 O2(g) → CO2(g) + 2 H2O(g)

문제 6a

Several processes are given in the table and labeled as endo- thermic or exothermic and given a sign for ∆H°. Which process is labeled with the correct sign of ∆H° and correct classification as endothermic or exothermic? (LO 9.8) Process (a) Ammonium nitrate dissolves in water, and the temperature of the solution decreases.

문제 6b

Several processes are given in the table and labeled as endo- thermic or exothermic and given a sign for ∆H°. Which process is labeled with the correct sign of ∆H° and correct classification as endothermic or exothermic? (LO 9.8) Process (b) Methane, the main component of natural gas, is burned to produce a flame on a stovetop.

문제 6c

문제 6d

문제 7

How much heat is required to raise a 50.0 g piece of iron from 25 °C to its melting point of 1538 °C? The specific heat capacity for iron is 0.451 J/g•°C. (a) 34.1 kJ (b) 168 kJ (c) 12.1 kJ (d) 6.78 kJ

문제 9

A 25.0 g piece of granite at 100.0°C was added to 100.0 g of water of 25.0°C, and the temperature rose to 28.4°C. What is the specific heat capacity of the granite? (The specific heat capacity for water is 4.18 J/(g•°C).) (LO 9.10) (a) 0.563 J/(g•°C) (b) 1.53 J/(g•°C) (c) 0.992 J/(g•°C) (d) 0.794 J/(g•°C)

문제 10

When 12.5 g of NH4NO3 is dissolved in 150.0 g of water of 25.0 °C in a coffee cup calorimeter, the final temperature of the solution of 19.7 °C. Assume that the specific heat of the solution is the same as that of water, 4.18 J/(g•°C). What is the ΔH per mol of NH4NO3? (LO 9.10) NH4NO3 (s) → NH4+ (aq) + NO3−(aq) ΔH = ? (a) +3.60 kJ (b) +23.0 kJ (c) +21.3 kJ (d) −3.60 kJ

문제 35a

Imagine a reaction that results in a change in both volume and temperature: (a) Has any work been done? If so, is its sign positive or negative?

문제 35b

Imagine a reaction that results in a change in both volume and temperature:

(b) Has there been an enthalpy change? If so, what is the sign of ∆H? Is the reaction exothermic or endothermic?

문제 36a

Redraw the following diagram to represent the situation (a) when work has been gained by the system and

문제 36b

Redraw the following diagram to represent the situation (b) when work has been lost by the system.

문제 37

A reaction is carried out in a cylinder fitted with a movable piston. The starting volume is V = 5.00 L, and the appa- ratus is held at constant temperature and pressure. Assum- ing that ∆H = -35.0 kJ and ∆E = -34.8 kJ, redraw the piston to show its position after reaction. Does V increase, decrease, or remain the same?

문제 38a

The reaction of A with B to give D proceeds in two steps: (1) A + B → C ΔH° = -20 kJ (2) C + B → D ΔH° = +50 kJ (3) A + 2B → D ΔH° = ? (a) Which Hess's law diagram represents the reaction steps and the overall reaction? Diagram 1 Diagram 2

문제 38b

The reaction of A with B to give D proceeds in two steps: (1) A + B → C ΔH° = -20 kJ (2) C + B → D ΔH° = +50 kJ (3) A + 2B → D ΔH° = ? (b) What is the value of ΔH° for the overall reaction A + 2 B → D ΔH° = ?

문제 39

Acetylene, C2H2, reacts with H2 in two steps to yield ethane, CH3CH3: (1) HC?CH + H2 → H2C?CH2 ΔH° = -175.1 kJ (2) H2C?CH2 + H2 → CH3CH3 ΔH° = -136.3 kJ Which arrow (a–c) in the Hess's law diagram corresponds to which step, an2d which a2rrow cor2responds to the net reaction? Where are the reactants located on the diagram, and where are the products located?

문제 40a

The following reaction is exothermic:

(a) Write a balanced equation for the reaction (red spheres represent A atoms and ivory spheres represent B atoms)

문제 40c

The following reaction is exothermic: (c) Is the reaction likely to be spontaneous at lower temperatures only, at higher temperatures only, or at all temperatures?

문제 43a

The following reaction of A₃ molecules is spontaneous. (a) Write a balanced equation for the reaction.

문제 44

What is the difference between heat and temperature? Between work and energy? Between kinetic energy and potential energy?

문제 45

What is internal energy?

문제 46

Which has more kinetic energy, a 1400-kg car moving at 115 km/h or a 12,000-kg truck moving at 38 km/h?

문제 47

Assume that the kinetic energy of a 1400-kg car moving at 115 km/h (Problem 9.46) could be converted entirely into heat. What amount of water could be heated from 20 °C to 50 °C by the car's energy? 4.184 J are required to heat 1 g of water by 1 °C.