Homework Answers
1.Reaction of gaseous H2 and O2 to yield one mole of liquid water releases 286 kJ of heat. If the H2O is formed in the gaseous state, the energy release will be smaller (around 242 kJ).
During change of phase of water some heat is required and this is noting both latent heat of vaporization for formation of 2 moles of water= (286-242)/2=44Kj/mol
2.It is lowers since this is essentially the ratio between P-T , the lower T, we need energy to evaporate + to heat , wheras at high T, we only need to evaporate.
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(a) Explain the difference between the enthalpy of formation of liquid and gaseous water,-286 and -...
The Standard enthalpy of vaporization of water at 100.0 oC is 40.66 KJ*mol-1. The Cp,m values for the liquid and the vap...
The Standard enthalpy of vaporization of water at 100.0
oC is 40.66 KJ*mol-1. The Cp,m
values for the liquid and the vapor water are, respectively, 75.3
and 33.58 J*K-1*mol-1. Assume that the heat
capacities are independent of temperature, and that the vapor
behaves as an ideal gas.
a) Calculate
sys in taking one mole of liquid water at 25.0
oC and 1.00 atm to gaseous water at 95.0 oC
and 0.500 atm.
b) Assume that the temperature and pressure of...
Calculate the standard combustion enthalpy of propylene at 25 ° C using the standard formation enthalpy...
Calculate the standard combustion enthalpy of propylene at 25 ° C using the standard formation enthalpy of liquid water (-286 kJ mol-1) and the following reactions: 1) CH2CHCH3 (g) + H2 (g) → CH3CH2CH3 (g); Δ? (1) = -125 kJ mol-1 2) CH3CH2CH3 (g) + 5O2 (g) → 3CO2 (g) + 4H2O (l); Δ? (2) = -2220 kJ mol-1 3) H 2 (g) + 0.5O2 (g) → H2O (l);Δ? ((3) = -286 kJ mol-1
1. (8 pts) Virtually every pchem textbook has a table of enthalpy values for 25°C. One...
1. (8 pts) Virtually every pchem textbook has a table of enthalpy values for 25°C. One use for these may be to calculate the enthalpy fora phase change such as boiling. However, not t0o many compounds boil at 25°C. You are going to calculate the percent difference between the heat of vaporization of ethanol using data for 25°C and that at its boiling point of 78°C. a) Write the chemical equation that shows the vaporization of 1 mol of ethanol...
The standard enthalpy of formation of gaseous water from its elements is -241.8 kJ/mol. H 2(g)...
The standard enthalpy of formation of gaseous water from its elements is -241.8 kJ/mol. H 2(g) + ½ O 2(g) → H 2O(g) What is the enthalpy change when 3 moles of hydrogen form?
The standard enthalpy of formation of NH_2(g) id -46 KJ mol^-1.The standard enthalpy of formation of...
The standard enthalpy of formation of NH_2(g) id -46 KJ mol^-1.The standard enthalpy of formation of H_2O(g) is -242 KJ middot mol^-1. The enthalpy of reaction is 906 kl. The standard enthalpy of formation of NO(g)is a. -754.5 kJ middot mol^-1 b. -362 kJ middot mol^-1 c. -196.5 kJ middot mol^-1 d. -90.5 k middot J-mol^-1 e. +90.5 kJ middot mol^- 1 f. +182.5 kJ middot mol^-1 g.+317 kJ middot mol^-1 h. +362 kJ middot mol^-1 i. +409 kJ middot...
water has a molar heat capacity of 75.38 J/(mol 12. Water has a molar heat capacity...
water has a molar heat capacity of 75.38 J/(mol
12. Water has a molar heat capacity of 75.38 J/(mol x °C) and its vaporization enthalpy at 100°C is 40.7 kJ/mol. How much energy is needed to convert 36 g liquid H20 at 70.0°C to steam at 100°C? A) 85.9 kJ B) 126 kJ C) 77.6 kJ D) 81.4 kJ E) 45.2 kJ
c Given the following standard molar entropies of formation (S) and enthalpies of combustion to gaseous...
c Given the following standard molar entropies of formation (S) and enthalpies of combustion to gaseous carbon dioxide and liquid water at 25 °c (AHe AH/kJ mol 393.5 -285.9 -1559.7 C(graphite) H2(g) C2Ho(g) 5.9 131.0 229.5 Calculate the enthalpy change (AH) and Gibbs energy change (AG) for the reaction 2C(graphite) +3H28)CH) datseatt Is this reaction thermodynamically possible? Give a reason for your answer. (10 marks) Explain why it is possible for endothermic processes to occur spontaneously. 15 marks]
Gaseous H2O is condensed at 100°C and the liquid water is cooled to 0°C followed by...
Gaseous H2O is condensed at 100°C and the liquid water is cooled to 0°C followed by freezing to solid water. What is the molar entropy change of the water? Consider the average specific heat of liquid water is 4.2 J/K g. The heat of vaporization at the boiling point and the heat of fusion at the freezing point at 2258.1 and 333.5 J/g, respectively.
9. The enthalpy of decomposition of gaseous water to oxygen and hydrogen at 298 K and 1 atm is 241.75 kJ/mol. Cal...
9. The enthalpy of decomposition of gaseous water to oxygen and hydrogen at 298 K and 1 atm is 241.75 kJ/mol. Calculate its value at 348 K. The molar heat capacity values (in J/K.mol) are: Cm (H20) 33.56, C.m (O2) 29.12, Cm (H2) 28.82.
1. (14 pts) Determine the standard molar enthalpy of formation of B2He (g) at 298 K...
1. (14 pts) Determine the standard molar enthalpy of formation of B2He (g) at 298 K using only the data below. The standard state of boron at 298 K is a crystalline solid, B(s). AH-2368 kJmol а) 2B (5) B,0, (s) AH-1941 kJ/mol 3H.O (g) +30, (e) B O, (s) 2) В,н, @ AH-242 kJmol но (3) H, (g) +
The Standard enthalpy of vaporization of water at 100.0
oC is 40.66 KJ*mol-1. The Cp,m
values for the liquid and the vapor water are, respectively, 75.3
and 33.58 J*K-1*mol-1. Assume that the heat
capacities are independent of temperature, and that the vapor
behaves as an ideal gas.
a) Calculate
sys in taking one mole of liquid water at 25.0
oC and 1.00 atm to gaseous water at 95.0 oC
and 0.500 atm.
b) Assume that the temperature and pressure of...
1. (8 pts) Virtually every pchem textbook has a table of enthalpy values for 25°C. One use for these may be to calculate the enthalpy fora phase change such as boiling. However, not t0o many compounds boil at 25°C. You are going to calculate the percent difference between the heat of vaporization of ethanol using data for 25°C and that at its boiling point of 78°C. a) Write the chemical equation that shows the vaporization of 1 mol of ethanol...
The standard enthalpy of formation of NH_2(g) id -46 KJ mol^-1.The standard enthalpy of formation of H_2O(g) is -242 KJ middot mol^-1. The enthalpy of reaction is 906 kl. The standard enthalpy of formation of NO(g)is a. -754.5 kJ middot mol^-1 b. -362 kJ middot mol^-1 c. -196.5 kJ middot mol^-1 d. -90.5 k middot J-mol^-1 e. +90.5 kJ middot mol^- 1 f. +182.5 kJ middot mol^-1 g.+317 kJ middot mol^-1 h. +362 kJ middot mol^-1 i. +409 kJ middot...
water has a molar heat capacity of 75.38 J/(mol
12. Water has a molar heat capacity of 75.38 J/(mol x °C) and its vaporization enthalpy at 100°C is 40.7 kJ/mol. How much energy is needed to convert 36 g liquid H20 at 70.0°C to steam at 100°C? A) 85.9 kJ B) 126 kJ C) 77.6 kJ D) 81.4 kJ E) 45.2 kJ
c Given the following standard molar entropies of formation (S) and enthalpies of combustion to gaseous carbon dioxide and liquid water at 25 °c (AHe AH/kJ mol 393.5 -285.9 -1559.7 C(graphite) H2(g) C2Ho(g) 5.9 131.0 229.5 Calculate the enthalpy change (AH) and Gibbs energy change (AG) for the reaction 2C(graphite) +3H28)CH) datseatt Is this reaction thermodynamically possible? Give a reason for your answer. (10 marks) Explain why it is possible for endothermic processes to occur spontaneously. 15 marks]
9. The enthalpy of decomposition of gaseous water to oxygen and hydrogen at 298 K and 1 atm is 241.75 kJ/mol. Calculate its value at 348 K. The molar heat capacity values (in J/K.mol) are: Cm (H20) 33.56, C.m (O2) 29.12, Cm (H2) 28.82.
1. (14 pts) Determine the standard molar enthalpy of formation of B2He (g) at 298 K using only the data below. The standard state of boron at 298 K is a crystalline solid, B(s). AH-2368 kJmol а) 2B (5) B,0, (s) AH-1941 kJ/mol 3H.O (g) +30, (e) B O, (s) 2) В,н, @ AH-242 kJmol но (3) H, (g) +
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