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Gibbs Free Energy & Reaction Spontaneity
Hess's Law
Specific Heat & Heat Transfer
Calorimetry
Standard Enthalpy of Formation
100
The hydrogenation of ethene gas under standard conditions (T = 298.15 K) shows a decrease in disorder (ΔS˚ = -0.1207 kJ/(mol•K)) during an exothermic reaction (ΔH˚ = -136.9 kJ/mol). Determine whether the reaction is spontaneous or nonspontaneous by calculating ΔG˚. C2H4 (g) + H2 (g) → C2H6 (g)
What is -100.9 kJ?
100
5. From the following heats of reaction: 2 H2 (g) + O2 (g) ---> 2 H2O (g) H = - 483.6 kJ 3 O2 (g) ---> 2 O3 (g) H = +284.6 kJ Calculate the heat of the reaction for: 3 H2 (g) + O3 (g) ---> 3 H2O (g)
What is -867.7 kJ?
100
The specific heat of ethanol is 2.46 J/g C. Find the heat energy required to raise the temperature of 193 g of ethanol from 19C to 35C.
What is 7,596.5 J?
100
A 445 g sample of ice at –58 C is heated until its temperature reaches –29 C. Find the change in heat content of the system.
What is 2.66 X 10 ^ 4 J?
100
The standard heats of formation of HCl (g) and HBr (g) are -92.0 kJ/mol and -36.4 kJ/mol respectively. Using this information, calculate ΔH for the following reaction: Cl2 (g) + 2 HBr (g) → 2 HCl (g) + Br2 (g)
What is -111.2 kJ?
200
Copper (I) sulfide reacts with sulfur to produce copper (II) sulfide under standard conditions. The process is exothermic (ΔH˚ = -26.7 kJ/mol) with a decrease in disorder (ΔS˚ = -19.7 J/(mol•K)). Determine the spontaneity of the reaction by calculating ΔG˚. Cu2S (s) + 2 S (s) → 2 CuS (s)
What is -20.83 kJ or -20,826.4 J ?
200
Calculate the enthalpy change of the reaction CH4 (g) + 2Cl2(g) ---> CCl4 (l) + 2 H2 (g), using thermochemical equations: a) C(s) + 2 Cl2 (g) ---> CCl4 (l) H = –128 kJ b) CH4 (g) ---> C(s) + 2H2 (g) H = + 75 kJ
What is -53 kJ?
200
When a 120 g sample of aluminum absorbs 9612 J of heat energy, its temperature increases from 25C to 115C. Find the specific heat of aluminum. Include the correct unit.
What is .89 J / g C?
200
A 152 g sample of ice at –37 C is heated until it turns into liquid water at 0 C. Find the change in heat content of the system.
What is 6.22 X 10 ^ 4 J?
200
Calculate the standard H of formation for the reaction of sulfur dioxide with oxygen. 2SO2(g) + O2(g) ---> 2SO3(g) Standard Enthalpies of Formation (SO2(g) = –296.8 kJ/mol; SO3(g) = –395.7 kJ/mol)
What is -197.8 kJ?
300
For a certain process at 300.0 K, ΔG = -77.0 kJ/mol and ΔH = -56.9 kJ/mol. Find the entropy change for this process.
What is 67 J / mol K?
300
Use the information below to calculate H for the chemical reaction: 2NO2(g) ---> N2O4(g) N2(g) + 2O2(g) ---> 2NO2(g) H = 67.7 kJ N2(g) + 2O2(g) ---> N2O4(g) H = 9.7 kJ
What is -58 kJ?
300
The specific heat of lead is 0.129 J/g C. Find the amount of heat released when 2.4 mol of lead are cooled from 37.2 C to 22.5 C.
What is -943 J?
300
(Daily Double) In going from ice at –34 C to steam at 138 C, a sample of water absorbs 1.41 x 10^5 J. Find the mass of the sample.
What is 44.65 g?
300
Calculate the standard H of formation for the following reaction. C2H4(g) + H2(g) ---> C2H6(g) (H for C2H4(g) = 52.5 kJ/mol; H for C2H6(g) = –84.7 kJ/mol)
What is -137.2 kJ?
400
The entropy of a system at 337.1 K increases by 221.7 J/mol•K. The free energy value is found to be –717.5 kJ/mol. Calculate the change in enthalpy of this system.
What is -642.8 kJ?
400
(Daily Double) Given the following data: N2 (g) + O2 (g) ---> 2 NO (g) H = + 180.7 kJ 2 NO (g) + O2 (g) ---> 2 NO2 (g) H = - 113.1 kJ 2 N2O (g) ---> 2 N2 (g) + O2 (g) H = - 162.3 kJ Use Hess’s law to calculate Hrxn for the following reaction. N2O (g) + NO2 (g) ---> 3 NO (g)
What is +156.1 kJ?
400
How many kJ of energy are needed to raise the temperature of 165 mol of water from 10.55 C to 47.32 C?
What is 456.99 kJ?
400
If 59 g of water at 13 C are mixed with 87 g of water at 72 C, find the final temperature of the system.
What is 48.2 C?
400
Calculate the standard H of formation for the following reaction. Use your standard heats of formation table. C2H4 (g) + 3 O2 (g) ----> 2CO2 (g) + 2 H20 (g)
What is -1322.91 kJ?
500
In a system in which the enthalpy changed –447.1 kJ/mol and the entropy decreases by 75.1 kJ/mol•K, calculate the temperature at which the system will be at equilibrium.
What is 5.9534 K?
500
Given the following equations: 4 NH3(g) + 5 O2(g) → 4 NO(g) + 6 H2O(l) ΔH° = -1170 kJ 4 NH3(g) + 3 O2(g) → 2 N2(g) + 6 H2O(l) ΔH° = -1530 kJ Using these two equations, determine the heat of formation, ΔHf° , for nitrogen monoxide, NO.
What is 90 kJ?
500
A 25 g sample of iron (initially at 800.00 C) is dropped into 200 g of water (initially at 30.00 C). The final temperature of the system is 40.22 C. Find the specific heat of iron.
What is .45 J / g C?
500
A sample of ice at –12 C is placed into 68 g of water at 85 C. If the final temperature of the system is 24 C, find the mass of the ice.
What is 37.8 g?
500
Calculate the standard H for the dissolution of solid Ammonium Nitrate in water.
What is 25.7 kJ / mol ?