CHM 123 exam 3 study guide

The standard enthalpies of formation of ions in aqueous solutions are obtained by arbitrarily assigning a value of zero to H ions; that is, ΔHof[H+(aq)] = 0. HCl(g) --> H+(aq) + Cl−(aq) ΔHorxn= −74.9 kJ/mol calculate ΔHof for the Cl− ions.

-167.2 kJ/mol

H2 + F2 --> 2HF ΔHf = -537 kJ C + 2F2 --> CF4 ΔHf = -680 kJ 2C + 2H2 --> C2H4 ΔHf = 52.3 kJ calculate the ΔHrxn for the reaction of enthylene with F2: C2H4 + 6F2 ---> 2CF4 + 4HF

-2486.3 kJ

a 1.8g sample of solid phenol (C6H5OH (s)) was burned in a bomb calorimeter, which has a total heat capacity of 11.66kJ/C. The temp of the colorimeter plus its contents increased from 21.36C to 26.37C. what is the heat of combustion per "g" pf phenol

-32.45 kJ/g

You are given the following data: H2(g) → 2H(g) ΔHo= 436.4 kJ/mol Br2(g) → 2Br(g) ΔHo= 192.5 kJ/mol H2(g) + Br2(g) → 2HBr(g) ΔHo= −72.4 kJ/mol Calculate ΔHo for the reaction H(g) + Br(g) → HBr(g)

-350.65 kJ/mol

The first step in the industrial recovery of zinc from the zinc sulfide ore is roasting-that is, the conversion of ZnS to ZnO by heating: 2ZnS(s) + 3O2(g) →2ZnO(s) + 2SO2(g) ΔH = −879 kJ Calculate the heat (in kJ) associated with roasting 1 gram of zinc sulfide.

-4.51 kJ

Calcium oxide (CaO) is used to remove sulfur dioxide generated by coal-burning power stations: 2CaO(s) + 2SO2(g) +O2(g) → 2CaSO4(s) Calculate the enthalpy change for this if 6.50 × 105 g of SO2 are removed by this process every day.

-5.08 x 10^6 kJ

A 0.1326 g sample of magnesium was burned in an oxygen bomb calorimeter. The total heat capacity of the calorimeter plus water was 5,760 J/°C. If the temperature rise of the calorimeter with water was 0.570°C, calculate the enthalpy of combustion of magnesium. Mg(s) + 1/2O2(g) →MgO(s)

-602 kJ/mol

a 0.1326g sample of magnesium was burned in an oxygen bomb calorimeter. The total heat capacity o the calorimeter plus water was 5760 J/C. If the temperature rise of the calorimeter with water was 0.570 C. calculate the enthalpy of combustion of magnesium Mg(s) + 1/2O2(g) --> MgO(s)

-602 kJ/mol

the internal energy can be increased by...

-transferring heat from the surroundings to the system -doing work on the system

when solutions containing silver ions and chloride ions are mixed, silver chloride precipitates: Ag+(aq) + Cl-(aq) ---> AgCl (s) ∆H=-65.5 kj calculate ∆H when 9.25 x 10^-4 mol of AgCl dissolves in water

.06059 kJ

A piece of silver with a mass 427 g has a heat capacity of 101.2 J/°C. What is the specific heat of silver?

.237 J/g ·°C

specific heat of water

4.184 J/gC

the value of ΔH for the reaction below is -126 kJ. _________kJ are released when 2 mol of NaOH is formed in the reaction. 2Na2O2(s) + 2H2O(l) --> 4NaOH(s) + O2(g)

63 kJ

Predict the value of ΔHof (greater than, less than, or equal to zero) for these elements at 25°C: Br2(l)

=0

qsolution =

Cs * msolution * ∆T

The ΔU of a system that absorbs 12.4 J of heat and does 4.2 J of work on the surroundings is ________ J. A) 16.6 B) 12.4 C) 4.2 D) -16.6 E) 8.2

E

first law of thermodynamics

Energy can be transferred and transformed, but it cannot be created or destroyed.

q

Heat energy (heat flow)

w system equation

Wsys = -PΔV

The standard Gibbs free energy of formation of ________ is zero. (a) Mn (s) (b) I2 (s) (c) Cu (s)

abc

constant volume

bomb calorimeter

liquid water to gaseous water

endothermic

system

the portion of the universe that is singled out for study

Determine the amount of heat (in kJ) associated with the production of 5.64 × 104 g of ammonia according to the following equation. N2(g) + 3H2(g) ---> 2NH3 ΔH°rxn = −92.6 kJ Assume that the reaction takes place under standard-state conditions at 25°C.

-1.53 x10^5

methanol (CH3OH) is used as a fuel in race cars calculate the heat produced by combustion per liter of methanol (methanol has a density of .791 g/ml) ΔH = -638.5 kJ/mol CH3OH(l) + 3/2O2(g) ---> CO2(g) + 2H2O(l)

-1.58 x 10^4 kJ/L

Calculate the heats of combustion for the following reactions. Use the standard enthalpies of formation. b) 2H2S(g) + 3O2(g) → 2H2O(l) + 2SO2(g)

-1144.68 kJ/mol

Calculate the heat (in kJ) associated with 496 g of white phosphorus burning in air according to the equation P4(s) + 5O2(g) → P4O10(s) ΔH = −3013 kJ / mol

-12,063 kJ

Calculate the heats of combustion for the following reactions. Use the standard enthalpies of formation. (a) C2H4(g) + 3O2(g) → 2CO2(g) + 2H2O(l)

-1410.9 kJ/mol

The standard enthalpies of formation of ions in aqueous solutions are obtained by arbitrarily assigning a value of zero to H ions; that is, ΔHof[H+(aq)] = 0. a) for the following reaction HCl(g) H+(aq) + Cl−(aq) ΔHorxn = -74.9 kJ/mol calculate ΔHof for the Cl− ions.

-167.2 kJ/mol

A sample of nitrogen gas expands in volume from 1.2 to 6.0 L at constant temperature. Calculate the work done in joules if the gas expands against a constant pressure of 4.9 atm:

-2.38 x 10^3 J

A balloon 17.0 m in diameter is inflated with helium at 25°C. Calculate the work done (in kJ) during the inflation process if the atmospheric pressure is 97.7 kPa.

-2.51 x 10^5 kJ

A balloon 17.0 m in diameter is inflated with helium at 21°C. Calculate the work done (in kJ) during the inflation process if the atmospheric pressure is 97.7 kPa.

-2.51 x10^5 kJ

A sample of nitrogen gas expands in volume from 1.3 to 6.5 L at constant temperature. Calculate the work done in joules if the gas expands against a constant pressure of 5.5 atm:

-2.9 x 10^3

Calculate the heat (in kJ) associated with the cooling of 391 g of mercury from 65.9°C to 12.0°C.

-2.93 kJ

calculate the heat combustion for the following reaction 2C2H2 (g) + 5O2 (g) --> 4CO2 (g) + 2H2O (l)

-2598.8

find ΔHrxn for the reaction: 2Na(s) + 2H2O(l) --> 2NaOH(aq) + 2H2(g) (ΔHfNaOH = -426.8 kJ/mol ; ΔHf H2O = -285.5 kJ/mol)

-282.6 kJ

A gas expands from 248 mL to 974 mL at a constant temperature. Calculate the work done (in joules) by the gas if it expands (a) against a constant pressure of 4.00 atm w =

-294 J

Calculate the heat (in kJ) associated with the cooling of 305 g of mercury from 84.1°C to 12.0°C.

-3.057 kJ

Calculate the heat (in kJ) associated with the cooling of 348 g of mercury from 79.9°C to 12.0°C.

-3.296 kJ

A sample of nitrogen gas expands in volume from 1.2 to 6.0 L at a constant temperature. Calculate the work done in joules if the gas expands against a constant pressure of 0.73 atm:

-3.35 x 10^2 J

A sample of nitrogen gas expands in volume from 1.3 to 6.5 L at constant temperature. Calculate the work done in joules if the gas expands against a constant pressure of 0.68 atm:

-3.6 x 10^2 J

when solutions containing silver ions and chloride ions are mixed, silver chloride precipitates: Ag+(aq) + Cl-(aq) ---> AgCl (s) ∆H=-65.5 kj calculate ∆H for the formation of 8.00g of AgCl

-3.65 kJ

when solutions containing silver ions and chloride ions are mixed, silver chloride precipitates: Ag+(aq) + Cl-(aq) ---> AgCl (s) ∆H=-65.5 kj calculate ∆H for formation of 0.46 mol of AgCl by this reaction?

-30.13 kJ

a 1.8g sample of solid phenol (C6H5OH (s)) was burned in a bomb calorimeter, which has a total heat capacity of 11.66kJ/C. The temp of the colorimeter plus its contents increased from 21.36C to 26.37C. what is the change in enthalpy per mole of phenol

-3057 kJ/mol

The first step in the industrial recovery of zinc from the zinc sulfide ore is roasting-that is, the conversion of ZnS to ZnO by heating: 2ZnS(s) + 3O2(g) →2ZnO(s) + 2SO2(g) ΔH = −879 kJ Calculate the heat (in kJ) associated with roasting 1 gram of zinc sulfide.

-4.51kJ

Determine the amount of heat (in kJ) associated with the production of 1.77 × 104 g of ammonia according to the following equation. N2(g) + 3H2(g) 2NH3 ΔH°rxn = −92.6 kJ assume that the reaction takes place under standard-state conditions at 25°C. Enter your answer in scientific notation.

-4.81 x 10^4 kJ

a certain gas expands in volume from 2.0L to 6.0L at constant temperature. Calculate the work done by the gas if it expands a) against a constant pressure of 1.2 atm

-4.9x10^2

Benzene (C6H6) burns in air to produce carbon dioxide and liquid water. Calculate the change in heat (in kilojoules) per gram of the compound reacted with oxygen. The standard enthalpy of formation of benzene is 49.04 kJ/mol.

-41.83 kJ/g

When 1.703 g of naphthalene (C10H8) is burned in a constant-volume bomb calorimeter at 298 K, 68.45 kJ of heat is evolved. Calculate ΔU and w for the reaction on a molar basis. ΔU =

-5,152.8 kJ/mol

Calcium oxide (CaO) is used to remove sulfur dioxide generated by coal-burning power stations: 2CaO(s) + 2SO2(g) +O2(g) → 2CaSO4(s) Calculate the enthalpy change for this if 6.70 × 105 g of SO2 are removed by this process every day.

-5.24 x 10^6 kJ

When 1.933 g of naphthalene (C10H8) is burned in a constant-volume bomb calorimeter at 298 K, 77.70 kJ of heat is evolved. Calculate ΔU and w for the reaction on a molar basis. ΔU =

-5153 kJ/mol 0 kJ/mol

The standard enthalpies of formation of ions in aqueous solutions are obtained by arbitrarily assigning a value of zero to H ions; that is, ΔHof[H+(aq)] = 0. HCl(g) --> H+(aq) + Cl−(aq) ΔHorxn= −74.9 kJ/mol Given that ΔHof for OH− ions is −229.6 kJ/mol, calculate the enthalpy of neutralization when 1 mole of a strong monoprotic acid (such as HCl) is titrated by 1 mole of a strong base (such as KOH) at 25°C.

-56.2 kJ/mol

The standard enthalpies of formation of ions in aqueous solutions are obtained by arbitrarily assigning a value of zero to H ions; that is, ΔHof[H+(aq)] = 0. a) for the following reaction HCl(g) H+(aq) + Cl−(aq) ΔHorxn = -74.9 kJ/mol b)Given that ΔHof for OH− ions is −229.6 kJ/mol, calculate the enthalpy of neutralization when 1 mole of a strong monoprotic acid (such as HCl) is titrated by 1 mole of a strong base (such as KOH) at 25°C.

-56.2 kJ/mol

when 0.560g of Na(s) reacts with excess F2(g) to form NaF(s), 13.8 kJ of heat is evolved at standard state conditions. What is the standard enthalpy of formation (ΔHf) of NaF(s)?

-570 kJ/mol

Acetylene (C2H2) and benzene (C6H6) have the same empirical formula. In fact, benzene can be made from acetylene as follows: 3C2H2(g) → C6H6(l) The enthalpies of combustion for C2H2 and C6H6 are −1299.4 kJ/mol and −3267.4 kJ/mol, respectively. Calculate the standard enthalpies of formation of C2H2 and C6H6. Assume that the products of the combustions are CO2(g) and H2O(l). Calculate the enthalpy change for the formation of C6H6 from C2H2. ΔHrxn =

-630.8 kJ/mol

Given that 2Al(s) + 3/2O2(g) → Al2O3(s) ΔHorxn=−1601 kJ/mol 2Fe(s) + 3/2O2(g) → Fe2O3(s) ΔHorxn =−821 kJ/mol calculate the standard enthalpy change for the following reaction: 2Al(s) + Fe2O3(s) → 2Fe(s) + Al2O3(s)

-7.8 x 10^2 kJ

Given that 2Al(s) + 32O2(g) → Al2O3(s) ΔHorxn=−1601 kJ/mol and. 2Fe(s) + 3/2O2(g) → Fe2O3(s) ΔHorxn=−821 kJ/mol calculate the standard enthalpy change for the following reaction: 2Al(s) + Fe2O3(s) → 2Fe(s) + Al2O3(s)

-7.8 x 10^2 kJ

Calculate the heat (in kJ) associated with 311 g of white phosphorus burning in air according to the equation P4(s) + 5O2(g) → P4O10(s) ΔH = −3013 kJ / mol

-7564 kJ

A quantity of 1.922 g of methanol (CH3OH) was burned in a constant-volume bomb calorimeter. Consequently, the temperature rose by 4.92°C. If the heat capacity of the bomb plus water was 9.77 kJ / °C, calculate the molar heat of combustion of methanol.

-801 kJ / mol

A quantity of 1.922 g of methanol (CH3OH) was burned in a constant-volume bomb calorimeter. Consequently, the temperature rose by 5.76°C. If the heat capacity of the bomb plus water was 8.51 kJ / °C, calculate the molar heat of combustion of methanol.

-817 kJ / mol

C(graphite) + O2(g) → CO2(g) ΔHorxn = −393.5 kJ/mol H2(g) + 1/2O2(g)→ H2O(l) ΔHorxn=−285.8 kJ/mol 2C2H6(g) + 7O2(g) → 4CO2(g) + 6H2O(l) ΔHorxn = −3119.6 kJ/mol calculate the enthalpy change for the reaction below: 2 C(graphite) + 3H2(g) → C2H6(g)

-84.6 kJ

Enter your answer in the provided box. From the following data, C(graphite) + O2(g) →CO2(g) ΔHrxn = −393.5 kJ/mol H2(g) + 1/2O2(g) → H2O(l) ΔHrxn = −285.8 kJ/mol 2C2H6(g) + 7O2(g) → 4CO2(g) + 6H2O(l) ΔHrxn = −3119.6 kJ/mol calculate the enthalpy change for the reaction below: 2 C(graphite) + 3H2(g) → C2H6(g)

-84.6 kJ

Enter your answer in the provided box.A quantity of 1.922 g of methanol (CH3OH) was burned in a constant-volume bomb calorimeter. Consequently, the temperature rose by 5.52°C. If the heat capacity of the bomb plus water was 9.32 kJ / °C, calculate the molar heat of combustion of methanol.

-858 kJ / mol

consider the following reactions: 2Mg(s) + O2 (g) --> 2MgO(s) ∆H = -1204 calculate the amount of heat transferred when 3.57g of Mg(s) react at constant pressure.

-88.4 kJ

Calculate the heat (in kJ) associated with 371 g of white phosphorus burning in air according to the equation P4(s) + 5O2(g) → P4O10(s)ΔH = −3013 kJ / mol

-9023 kJ

H2(g) + 1/2 O2(g) --> H2O(l) ΔHf = -285.8 kJ/mol H2O2(l) --> H2(g) +O2(g) ΔHrxn = 187.6 kJ/mol calculate ΔHfHrxn for the reaction H2O2 (l) --> H2O(l) + 1/2O2 (g)

-98.2 kJ

Given the following ΔH° values, H2(g) + 1/2O2(g) → H2O(l) ΔH°f = -285.8 kJ/mol H2O2(l) → H2(g) + O2(g) ΔH°rxn = 187.6 kJ/molcalculate ΔH°rxn for the reaction H2O2(l) → H2O(l) + 1/2O2(g).

-98.2 kJ/mol

The combustion of how many moles of ethane (C2H6) would be required to heat 951 g of water from 25.0°C to 83.0°C? (Assume liquid water is formed during the combustion.)

.148 mol ethane

The combustion of how many moles of ethane (C2H6) would be required to heat 797 g of water from 25.0°C to 98.0° C? (Assume liquid water is formed during the combustion.)

.156 mol ethane

A piece of silver with a mass 313 g has a heat capacity of 74.2 J/°C. What is the specific heat of silver?

.237 J/g·°C

A piece of silver with a mass 316 g has a heat capacity of 74.9 J/°C. What is the specific heat of silver?

.2370 J/g·°C

A piece of copper with a mass of 218 g has a heat capacity of 83.9 J/°C. What is the specific heat of copper?

.385 J/gC

an 6.11g sample of CaCO3(s) absorbs 84J of heat at constant pressure, upon which the temp of the sample increases from 19.2 C to 35.9 C. What is the specific heat of calcium carbonate?

.8232

a certain gas expands in volume from 2.0L to 6.0L at constant temperature. Calculate the work done by the gas if it expands a) against a vacuum

0

A gas expands from 248 mL to 974 mL at a constant temperature. Calculate the work done (in joules) by the gas if it expands (a) against a vacuum. w =

0 J

When 1.703 g of naphthalene (C10H8) is burned in a constant-volume bomb calorimeter at 298 K, 68.45 kJ of heat is evolved. Calculate ΔU and w for the reaction on a molar basis. w =

0 kJ/mol

∆Hf of any element is

0 kj/mol

A man ate 0.552 pound of cheese (an energy intake of 3.50 × 103 kJ). Suppose that none of the energy was stored in his body. What mass (in grams) of water would he need to perspire in order to maintain his original temperature? (It takes 44.0 kJ to vaporize 1 mole of water.) Enter your answer in scientific notation.

1.43 x 10^3g

A man ate 0.725 pound of cheese (an energy intake of 4.60 × 103 kJ). Suppose that none of the energy was stored in his body. What mass (in grams) of water would he need to perspire in order to maintain his original temperature? (It takes 44.0 kJ to vaporize 1 mole of water.) Enter your answer in scientific notation.

1.88 x 10^3 g

1L x atm is how many J

101.3 J

Calculate the heat required when 2.50 mol of A reacts with excess B and A2B according to the reaction: 2A + B + A2B → 2AB + A2 Given: 2A + B --> A2B H= -25.0 kJ/mol 2A2B --> 2AB + A2 H= 35.0 kJ/mol

12.5 kJ

At what temperature (in K) will a reaction become spontaneous? ΔH is 115.0 kJ/mol and ΔS is 75.00 J/K ∙ mol.

1533

using the data in the table, estimate the temp at which the free-energy change for the transformation form I2(s) to I2(g) is zero. express the temp in C I2(g) 62.25 kJ/mol 260.57 J/mol*k I2(s) 0 kJ/mol 116.73 J/mol*k

160C

consider the following reactions: 2Mg(s) + O2 (g) --> 2MgO(s) ∆H = -1204 how many grams of MgO are produced during an enthalpy change of -239kJ

16g

A quantity of 5.40 × 102 mL of 0.650 M HNO3 is mixed with 5.40 × 102 mL of 0.325 M Ba(OH)2 in a constant-pressure calorimeter of negligible heat capacity. The initial temperature of both solutions is the same at 18.46°C. The heat of neutralization when 1.00 mol of HNO3 reacts with 0.500 mol Ba(OH)2 is −56.2 kJ/mol. Assume that the densities and specific heats of the solution are the same as for water (1.00 g/mL and 4.184 J/g · °C, respectively). What is the final temperature of the solution?

22.8 °C

A quantity of 5.40 × 102 mL of 0.850 M HNO3 is mixed with 5.40 × 102 mL of 0.425 M Ba(OH)2 in a constant-pressure calorimeter of negligible heat capacity. The initial temperature of both solutions is the same at 18.46°C. The heat of neutralization when 1.00 mol of HNO3 reacts with 0.500 mol Ba(OH)2 is −56.2 kJ/mol. Assume that the densities and specific heats of the solution are the same as for water (1.00 g/mL and 4.184 J/g · °C, respectively). What is the final temperature of the solution?

23.8 °C

A quantity of 3.10 × 102 mL of 0.900 M HNO3 is mixed with 3.10 × 102 mL of 0.450 M Ba(OH)2 in a constant-pressure calorimeter of negligible heat capacity. The initial temperature of both solutions is the same at 18.46°C. The heat of neutralization when 1.00 mol of HNO3 reacts with 0.500 mol Ba(OH)2 is −56.2 kJ/mol. Assume that the densities and specific heats of the solution are the same as for water (1.00 g/mL and 4.184 J/g · °C, respectively). What is the final temperature of the solution?

24.5 °C

when a 4.25g sample of solid ammonium nitrate dissolves in 60.0g of water in a coffee-cup calorimeter, the temp drops form 22.0C to 16.9C. calculate ∆H (in kJ/mol NH4NO3) for the solution process NH4NO3(s) ---> NH4(aq) + NO3(aq) assume the specific heat of the solution is the same as that of pure water (4.184 J/gC)

26 kJ/mol

calculate the heat released (kJ) in the reaction of 3.50 g of acetylene (C2H2) and excess hydrogen gas to form ethane gas: C2H2(g) + 2H2(g) --> C2H6(g) given: 2C2H2(g) +5O2(g) --> 4CO2(g) + 2H2O(g) ΔH = -2320 kJ/mol 2C2H6(g) + 7O2(g) ---> 4CO2(g) + 6H2O(g) ΔH = -3040 kJ/mol 2H2(g) + O2(g) --> 2H2O(g) ΔH = -572 kj/mol

28.5

Hsolid sodium peroxide (Na2O2) reacts with liquid water yielding aqueous sodium hydroxide and oxygen gas how much heat is released when 250.0 L of oxygen gas is produced from the reaction of sodium peroxide and water if the reaction is carried out in an open container at 1.00 atm pressure and 25C? Given ΔHf [Na2O(s)] = -510.9 kJ/mol ΔHf [NaOH(aq)] = -469.2 kJ/mol ΔHf [H2O(l)] = -285.8 kj/mol

2900 kJ

A 22.0 g block of copper at 45°C absorbs 2.50 kJ of heat. Given the specific heat of Cu is 0.385 J/g·°C what will be the final temperature of the Cu?

340 C

NH3(g) + HCl(g) --> NH4Cl(s) Given the following table of thermodynamic data, determine the temp (C) above which reaction is nonspontaneous NH3(g) -46.19 kJ/mol 192.5 J/mol*K HCl(g) -92.30 kJ/mol 186.69 J/mol*K NH4Cl(s) -314.4 kJ/mol 94.6 J/mol*K

345C

10.1 g CaO is dropped into a styrofoam coffee cup containing 157g H2O at 18.0 C If the following reaction occurs, what temperature ill the water reach, assuming that the cup is a perfect insulator and that the cup absorbs only a negligible amount of heat? (the specific heat of water is 4.18 J/gC) CaO(s) + H2O(l) --> Ca(OH)2(s) ΔHrxn = -64.8 kJ/mol

35.8 C

ΔH for the reaction: IF5(g) ---> IF3(g) + F2(g) is _______ kJ. given the data below. IF(g) + F2(g) -->IF3(g) ΔH = -390kJ IF(g) + 2F2(g) --> IF5(g) ΔH = -745kJ

355

what is the molar heat capacity (in J/mol*k) of liquid bromine? the specific heat of liquid bromine is .226 J/g*k

36.1J/mol*k

calculate the standard enthalpy change for the following: Mg(OH)2 (s) --> MgO(s) + H2O (l)

37.06

the normal boiling point of methanol is 64.7 C and the molar enthalpy of vaporization if 71.8kJ/mol. The value of ΔS wjem 1.75 mol of CH3OH(l) vaporizes at 64.7 C is ____ J/k

372 J/K???

sodium carbonate can be made by heating sodium bicarbonate 2NaHCO3(s) --> Na2CO3(s)+ CO2(g) + H2O(g) given that ΔH = 128.9 kJ/mol and ΔG = 33.1 kJ/mol at 25 C, above what minimum temp will the reaction become spontaneous under state conditions

401K

Consider the reaction 2H2O(g) → 2H2(g) + O2(g)ΔH = 483.6 kJ / mol If 2.0 moles of H2O(g) are converted to H2(g) and O2(g) against a pressure of 1.0 atm at 165°C, what is ΔU for this reaction?

472 kJ

Consider the reaction 2H2O(g) → 2H2(g) + O2(g)ΔH = 483.6 kJ / mol If 2.0 moles of H2O(g) are converted to H2(g) and O2(g) against a pressure of 1.0 atm at 185°C, what is ΔU for this reaction?

479 kJ

consider the reaction 2H2O(g) → 2H2(g) + O2(g)ΔH = 483.6 kJ / mol If 2.0 moles of H2O(g) are converted to H2(g) and O2(g) against a pressure of 1.0 atm at 155C, what is ΔU for this reaction?

480 kJ

The enthalpy of combustion of benzoic acid (C6H5COOH) is commonly used as the standard for calibrating constant-volume bomb calorimeters; its value has been accurately determined to be −3226.7 kJ/mol. When 2.7117 g of benzoic acid are burned in a calorimeter, the temperature rises from 21.84°C to 26.67 °C. What is the heat capacity of the bomb? (Assume that the quantity of water surrounding the bomb is exactly 2250 g.)

5.42 kJ/°C

Enter your answer in the provided box. The enthalpy of combustion of benzoic acid (C6H5COOH) is commonly used as the standard for calibrating constant-volume bomb calorimeters; its value has been accurately determined to be −3226.7 kJ/mol. When 3.4737 g of benzoic acid are burned in a calorimeter, the temperature rises from 20.84°C to 26.67°C. What is the heat capacity of the bomb? (Assume that the quantity of water surrounding the bomb is exactly 2250 g.)

6.33 kJ/°C

calculate the standard enthalpy change for the following: 2CuO (s) + NO (g) --> Cu2 (s) + NO2 (g)

87.1

The enthalpy of combustion of benzoic acid (C6H5COOH) is commonly used as the standard for calibrating constant-volume bomb calorimeters; its value has been accurately determined to be −3226.7 kJ/mol. When 2.7031 g of benzoic acid are burned in a calorimeter, the temperature rises from 20.84°C to 24.67°C. What is the heat capacity of the bomb? (Assume that the quantity of water surrounding the bomb is exactly 2250 g.)

9.23 kJ/°C

A man ate 0.370 pound of cheese (an energy intake of 2350 kJ). Suppose that none of the energy was stored in his body. What mass (in grams) of water would he need to perspire in order to maintain his original temperature? (It takes 44.0 kJ to vaporize 1 mole of water.) Enter your answer in scientific notation.

9.62 x 10^2 g

Predict the value of ΔHof (greater than, less than, or equal to zero) for these elements at 25°C: Br2(g)

>0

A sample of iron absorbs 81.0 J of heat, upon which the temperature of the sample increases from 19.7 ℃ to 28.2℃ If the specific heat of iron is 0.450 J/g-K, what is the mass (in grams) of the sample? A) 21.2 g B) 4.29 g C) -21.2 g D) 0.0472 g E) 3.83 g

A

CH3OH (l) decomposes into carbon monoxide and hydrogen gas in the presence of heat. How much heat is consumed when 5.75 g of CO (g) is formed? ΔH° = +128.1 kJ. A) 26.3 kJ B) 23.3 kJ C) 62.0 kJ D) 162 kJ E) 8.3 kJ

A

Given the data in the table below, ΔH°rxn for the reaction 4NH3 (g) + 5O2 (g) → 4NO (g) + 6H2O (l) is ________ kJ. A) -1172 B) -150 C) -1540 D) -1892 E) The ΔH°f of O2 (g) is needed for the calculation.

A

Given the following reactions Fe2O3 (s) + 3CO (s) → 2Fe (s) + 3CO2 (g) ΔH = -28.0 kJ 3Fe (s) + 4CO2 (s) → 4CO (g) + Fe3O4 (s) ΔH = +12.5 kJ the enthalpy of the reaction of Fe2O3 with CO 3Fe2O3 (s) + CO (g) → CO2 (g) + 2Fe3O4 (s) is ________ kJ. A) -59.0 B) 40.5 C) -15.5 D) -109 E) +109

A

Given the following reactions N2 (g) + 2O2 (g) → 2NO2 (g) ΔH = 66.4 kJ 2NO (g) + O2 (g) → 2NO2 (g) ΔH = -114.2 kJ the enthalpy of the reaction of the nitrogen to produce nitric oxide N2 (g) + O2 (g) → 2NO (g) is ________ kJ. A) 180.6 B) -47.8 C) 47.8 D) 90.3 E) -180.6

A

Given the following table of thermodynamic data, complete the following sentence. The vaporization of H2O2 (l) is ________. H2O2(g) H: -136.3 S: 232.6 H2O2(l) H: -187.8 S: 110 A) nonspontaneous at low temperature and spontaneous at high temperature B) spontaneous at low temperature and nonspontaneous at high temperature C) spontaneous at all temperatures D) nonspontaneous at all temperatures E) not enough information given to draw a conclusion

A

How many joules of heat are absorbed when the temperature of a 13.9 g sample of CaCO3 (s) increases from 21.7 ℃ to 33.3 ℃ Specific heat of calcium carbonate is 0.82 J/g-K . A) 130 J B) 0.68 J C) s-130 J D) -0.68 J E) 9.5 J

A

How many kJ of heat are released when 15.75 g of Ba (s) reacts completely with oxygen gas to form BaO (s)? ΔH° = -1107 kJ. A) 63.5 kJ B) 20.8 kJ C) 114 kJ D) 70.3 kJ E) 35.1 kJ

A

Of the following, ΔH°f is not zero for ________. A) Sc (g) B) Si (s) C) P4 (s, white) D) Br2 (l) E) Ca (s)

A

The temperature of a 24.3 g sample of gold increases from 23.7 ℃ to 31.5℃ If the specific heat of gold is 0.129 J/g-K. How many joules of heat are absorbed? A) 24.5 J B) 0.0414 J C) -24.5 J D) 0.293 J E) 1.01 J

A

A reaction that is spontaneous as written ________. A) is very rapid B) will proceed without outside intervention C) is also spontaneous in the reverse direction D) has an equilibrium position that lies far to the left E) is very slow

B

For a given process at constant pressure, w is positive. This means that the process involves ________. A) work being done by the system on the surroundings B) work being done by the surroundings on the system C) no work being done D) an equal amount of work done on the system and by the system E) work being done against a vacuum

B

For which one of the following reactions is ΔH°rxn equal to the heat of formation of the product? A) N2 (g) + 3H2 (g) → 2NH3 (g) B) (1/2)N2 (g) + O2 (g) → NO2 (g) C) 6C (s) + 6H (g) → C6H6 (l) D) P (g) + 4H (g) + Br (g) → PH4Br (l) E) 12C (g) + 11H2 (g) + 11O (g) → C6H22O11 (g)

B

The enthalpy change for the following reaction is -483.6 kJ: 2H2 (g) + O2 (g) → 2H2O (g) Therefore, the enthalpy change for the following reaction is ________ kJ. 4H2 (g) + 2O2 (g) → 4H2O (g) A) -483.6 B) -967.2 C) 2.34 × 105 D) 483.6 E) 967.2

B

The value of ΔG° at 373 K for the oxidation of solid elemental sulfur to gaseous sulfur dioxide is ________ kJ/mol. At 298 K, ΔH° for this reaction is -269.9 kJ/mol, and ΔS° is +11.6 J/K. A) -300.4 B) -274.2 C) -4,597 D) +300.4 E) +4,597

B

The value of ΔU for a system that performs 151 kJ of work on its surroundings and loses 79 kJ of heat is ________ kJ. A) +230. B) -230. C) +72 D) -72 E) -151

B

When a system ________, ΔU is always negative. A) absorbs heat and does work B) gives off heat and does work C) absorbs heat and has work done on it D) gives off heat and has work done on it E) None of the above is always negative.

B

ΔS is positive for the reaction ________. A) Pb(NO3 )2 (aq) + 2KI(aq) → PbI2 (s) + 2KNO3 (aq) B) 2H2O (g) → 2H2 (g) + O2 (g) C) H2O (g) → H2O (s) D) NO (g) + O2 (g) → NO2 (g) E) Ag⁺ (aq) + Cl⁻ (aq) → AgCl (s)

B

) The value of ΔH° for the reaction below is -790 kJ. The enthalpy change accompanying the reaction of 0.95 g of S is ________ kJ. 2S (s) + 3O2 (g) → 2SO3 (g) A) 23 B) -23 C) -12 D) 12 E) -790

C

Given the data in the table below, ΔH°rxn for the reaction 2SO2 (g) + O2 (g) → 2SO3 (g) is ________ kJ. A) -99 B) 99 C) -198 D) 198 E) The ΔH°f of O2 (g) is needed for the calculation.

C

Given the following table of thermodynamic data, complete the following sentence. The vaporization of Ti is ________. Substance: TiCl4(g) TiCl4(1) Delta Hf (kJ/mol) -763.2 -804.2 S (J/mol*K) -804.2 221.9 A) spontaneous at all temperatures B) spontaneous at low temperature and nonspontaneous at high temperature C) nonspontaneous at low temperature and spontaneous at high temperature D) nonspontaneous at all temperatures E) not enough information given to draw a conclusion

C

Which of the following gases has the largest entropy at 25℃ and 1 atm? A) Cl2 B) F2 C) I2 D) Br2 E) O3

C

Which one of the following processes produces a decrease of the entropy of the system? A) dissolving sodium chloride in water B) sublimation of naphthalene C) dissolving oxygen in water D) boiling of alcohol E) explosion of nitroglycerine

C

Δ S is positive for the reaction ________. A) Pb(NO3)2 (aq) + 2KI(aq) → PbI2 (s) + 2KNO3 (aq) B) H2O (g) → H2O (s) C) 2H2O (g) → 2H2 (g) + O2 (g) D) NO (g) + O2 (g) → NO2 (g) E) Ag+ (aq) + Cl- (aq) → AgCl (s)

C

ΔS is positive for the reaction ________. A) CaO (s) + CO2 (g) → CaCO3 (s) B) N2 (g) + 3H2 (g) → 2NH3 (g) C) 2SO3 (g) → 2SO2 (g) + O2 (g) D) Ag⁺ (aq) + Cl⁻ (aq) → AgCl (s) E) H2O (l) → H2O (s)

C

which of the following has the largest entropy at 25C and 1 atm a)C3H4 b)C3H6 c)C3H8 d)H2 e)C2H6

C3H8

a 1.8g sample of solid phenol (C6H5OH (s)) was burned in a bomb calorimeter, which has a total heat capacity of 11.66kJ/C. The temp of the colorimeter plus its contents increased from 21.36C to 26.37C. Write the balanced equation

C6H5OH + 7O2 --> 6CO2 + 3H2O

methanol (CH3OH) is used as a fuel in race cars write the balanced equation for the combustion of liquid methanol in air

CH3OH(l) + 3/2O2(g) ---> CO2(g) + 2H2O(l)

specific heat capacity equation (solving for specific heat)

Cs= q/(∆T*m)

A 10.1 g sample of NaOH is dissolved in 250.0 g of water in a coffee-cup calorimeter. The temperature increases from 23.0 °C to ________°C. Specific heat of liquid water is 4.18 J/g-K and ΔH for the dissolution of sodium hydroxide in water is - 44.4 kJ/mol. A) 35.2 B) 24.0 C) 33.7 D) 33.3 E) 40.2

D

A decrease in the entropy of the system is observed for the reaction ________. A) 4 NH3 (g) + 5 O2 (g) → 4 NO (g) + 6 H2O (g) B) 2 HgO (s) → 2 Hg (l) + O2 (g) C) UF6 (s) → U (s) + 3F2 (g) D) K (s) + 1/2 I2 (g) → KI (s) E) H2O (s) → H2O (g)

D

At what temperature will a reaction be spontaneous? ΔH = +22.2 kJ/mol and ΔS = +81.1 J/K-mol and assume both do not vary with temperature. A) at T > 298 K B) at T < 274 K C) at T < 298 K D) at T > 274 K E) at all temperatures

D

Given the following reactions N2 (g) + O2 (g) → 2NO (g) ΔH = +180.7 kJ 2N2O (g) → O2 (g) + 2N2 (g) ΔH = -163.2 kJ the enthalpy of reaction for 2N2O (g) → 2NO (g) + N2 (g) is ________ kJ. A) 145.7 B) 343.9 C) -343.9 D) 17.5 E) -145.7

D

The internal energy of a system ________. A) is the sum of the kinetic energy of all of its components B) is the sum of the rotational, vibrational, and translational energies of all of its components C) refers only to the energies of the nuclei of the atoms of the component molecules D) is the sum of the potential and kinetic energies of the components E) none of the above

D

The signs of ΔH° and ΔS° must be ________ and ________, respectively, for a reaction to be spontaneous at high temperatures but nonspontaneous at low temperatures. A) +, - B) -, + C) -, - D) +, + E) +, 0

D

The specific heat capacity of lead is 0.13 J/g-K. How much heat (in J) is required to raise the temperature of 15g of lead from 22 °C to 37 °C? A) 2.0 J B) -0.13 J C) 5.8 × 10-4 J D) 29 J E) 0.13 J

D

The value of ΔS° for the catalytic hydrogenation of acetylene to ethene, C2H2 (g) + H2 (g) → C2H4 (g) is ________ J/K∙ mol. A) +18.6 B) +550.8 C) +112.0 D) -112.0 E) -18.6

D

Which of the following is a statement of the first law of thermodynamics? A) Ek = ½ mv² B) A negative ΔH corresponds to an exothermic process. C) ΔU = Ufinal - Uinitial D) Energy lost by the system must be gained by the surroundings. E) 1 cal = 4.184 J (exactly)

D

Which of the following reactions would have a negative ΔS? A) NH4Cl (s) → NH3 (g) + HCl (g) B) PbCl2 (s) → Pb2+ (aq) + 2Cl- (aq) C) 2C (s) + O2 (g) → 2CO2 (g) D) 2SO2 (g) + O2 (g) → 2 SO3 (g) E) H2O (l) → H2O (g)

D

which of these species has the highest entropy (S) at 25C a) CH3OH(l) b) H2O(l) c) Ni(s) d) CO (g) e) MgCo3(s)

D?

A 50.0-g sample of liquid water at 25.0 °C is mixed with 23.0 g of water at 79.0 °C. The final temperature of the water is ________ °C. A) 123 B) 27.3 C) 52.0 D) 231 E) 42.0

E

The combustion of acetylene in the presence of excess oxygen yields carbon dioxide and water: 2C2H2 (g) + 5O2 (g) → 4CO2 (g) + 2H2O (l) The value of ΔS° for this reaction is ________ J/K ∙ mol. A) +689.3 B) +122.3 C) +432.4 D) -122.3 E) -432.4

E

The combustion of titanium with oxygen produces titanium dioxide: Ti (s) + O2 (g) → TiO2 (s) When 0.610 g of titanium is combusted in a bomb calorimeter, the temperature of the calorimeter increases from 25.00 °C to 50.50 °C. In a separate experiment, the heat capacity of the calorimeter is measured to be 9.84 kJ/K. The heat of reaction for the combustion of a mole of Ti in this calorimeter is ________ kJ/mol. A) 2.09 B) 4.14 C) -311 D) -0.154 E) -1.98 × 10⁴

E

second law of thermodynamics

Every energy transfer or transformation increases the entropy of the universe.

which is the more negative quantity at 25°C: ΔHof H2O(l) or ΔHof for H2O(g)?

H2O(l)

Acetylene (C2H2) and benzene (C6H6) have the same empirical formula. In fact, benzene can be made from acetylene as follows: 3C2H2(g) → C6H6(l) The enthalpies of combustion for C2H2 and C6H6 are −1299.4 kJ/mol and −3267.4 kJ/mol, respectively. Calculate the standard enthalpies of formation of C2H2 and C6H6. Assume that the products of the combustions are CO2(g) and H2O(l). Hof(C2H2) = Hof(C6H6) =

Hof(C2H2) = 226.6 kJ/mol Hof(C6H6) = 49.0 kJ/mol

Which of the following has a ΔH°f= 0 kJ/mol? O3(g) Cl-(aq) I2(s) NH3(aq) CO2(g)

I2(s)

Which of the following processes is endothermic, given the following: S(s) + O2(g) →SO2(g) ΔH = -299 kJ/mol S(s) + 3/2 O2(g) →SO3(g) ΔH = -395 kJ/mol S(s) + 3 O2(g) →2 SO3(g) 2 S(s) + 5/2 O2(g) → SO2(g) + SO3(g) SO3(g) →S(s) + 3/2 O2(g) 2 S(s) + 2 O2(g) →2 SO2(g) ½ S(s) + ½ O2(g) →½ SO2(g)

SO3(g) →S(s) + 3/2 O2(g)

Which of the following processes always results in an increase in the energy of a system? The system loses heat and does work on the surroundings. The system gains heat and has work done on it by the surroundings. The system loses heat and has work done on it by the surroundings. The system gains heat and does work on the surroundings. None of these is always true.

The system gains heat and has work done on it by the surroundings.

Which reaction produces an increase in the entropy of the system? A) Ag+ (aq) + Cl- (aq) → AgCl (s) B) CO2 (s) → CO2 (g) C) H2 (g) + Cl2 (g) → 2 HCl (g) D) N2 (g) + 3 H2 (g) → 2 NH3 (g) E) H2O (l) → H2O (s)

b

Which of the following statements is true? A) Processes that are spontaneous in one direction are spontaneous in the opposite direction. B) Processes are spontaneous because they occur at an observable rate. C) Spontaneity can depend on the temperature. D) All of the statements are true.

c

open system

can exchange matter and energy with its surroundings

∆H

change in enthalpy

constant pressure

coffee cup calorimeter

example of endothermic

cold pack

solid water to liquid water

endothermic

kinetic energy

energy associated with motion

thermal energy

energy associated with the random motions of atoms and molecules

chemical energy

energy stored within the structural units of chemical substances

surroundings

everything that lies outside the system being studied

closed system

exchanges energy but not matter with the surroundings

consider the following reactions: 2Mg(s) + O2 (g) --> 2MgO(s) ∆H = -1204 is the reaction exothermic or endo thermic

exothermic

gaseous water to liquid water

exothermic

liquid water to solid water

exothermic

4Al(s) + 3O2(g) --> 2Al2O3(s) ΔH = -3351 kJ is _____________, and thermal heat is __________ by the reaction

exothermic released

The quantity of energy gained by a system equals the quantity of energy gained by its surroundings.

false

increasing entropy

gas > liquid > solid

when a system ________, ΔU is always negative

gives off heat and does work

spontaneous

having no external cause, acting on impulse

-q

heat flows from system to the surroundings

+q

heat flows from the surroundings to the system

∆ enthalpy

heat of reaction (∆H)

example of exothermic

heat pack

An exothermic reaction causes the surroundings to

increase in temperature

the entropy of the universe _______ in any spontaneous process

increases

U

internal energy

entropy

measure of disorder (s)

Cm

molar heat capacity

isolated system

no exchange of energy or matter

specific heat capacity equation

q=m∆T

qsol calorimetetry equation

qcal = Ccal x ∆T

we can calculate ∆H for the reaction with this equation

qsoln = Cs x msoln x ∆T

qsolution and q reaction relationship

qsolution = -qreaction

non spontaneous

reaction requires a sustained input of energy

Cs

specific heat capacity

given that following table of thermodynamic data, H2(g) -136.3 kJ/mol 232.6 kJ/mol*k H2(l) -187.8 kJ/mol 110 J/mol*k complete the following sentence. The vaporization of H2

spon @ highT nonspon @ low temp

2C4H10(g) + 13O2(g) --> 8CO2(g) + 10H2O(g) ΔH is -125 kJ/mol and ΔS is +253 J/kmol. This reaction is _______.

spontaneous

hess's law

the ∆Hrxn is the sum of the individual steps

V

volume

Suppose a 50.0 g block of silver (specific heat = 0.2350 J/g·°C) at 100°C is placed in contact with a 50.0 g block of iron (specific heat = 0.4494 J/g·°C) at 0°C, and the two blocks are insulated from the rest of the universe. The final temperature of the two blocks

will be lower than 50C

w

work

+w

work being performed by surroundings on system

-w

work is being performed by system on the surroundings

the entropy of a pure crystalline substance at absolute zero is

zero

how is spontaneity measured

ΔG = ΔH - TΔS

methanol (CH3OH) is used as a fuel in race cars calculate the standard enthalpy change for the combustion reaction assuming that H2O is a product CH3OH(l) + 3/2O2(g) ---> CO2(g) + 2H2O(l)

ΔH = -726.5 kJ/mol

reversible

ΔSuni = ΔSsys + ΔSsurr = 0

irreversible

ΔSuni = ΔSsys + ΔSsurr > 0

which one of the following is always positive when a spontaneous process occurs

ΔSuniverse

ΔU equation

ΔU = q + w

When 1.531 g of naphthalene (C10H8) is burned in a constant-volume bomb calorimeter at 298 K, 61.54 kJ of heat is evolved. Calculate ΔU and w for the reaction on a molar basis.

ΔU= -5,153 kJ/mol w = 0 kJ/mol

ΔSrxn =

ΣnSproducts - ΣmSreactants

enthalpy of a state function equation

∆Hrxn = Σn∆Hf products - Σm∆Hf reactants