Full worked out solutions to the all problems below with explanations available here with 🔐 CHEMDUNN access.
Calculate the heat needed to take 13.6 g of ethanol (CH3CH2OH) from -50०C to 200०C.
Melting point: -114.5०C
Boiling point: 78.5०C
ΔHfusion : 26 cal/g
ΔHvaporation : 220 cal/g
Specific Heat Capacities:
Solid: 0.332 cal/ (g・०C)
Liquid: 0.588 cal/(g・०C)
Gas: 0.247 cal/(g・०C)
Enthalpy Calculations using:
Upon adding solid potassium hydroxide pellets to water the following reaction takes place:
KOH(s) → KOH(aq) + 43 kJ
Answer the following questions regarding the addition of 14.0g of KOH to water:
Does the beaker get warmer or colder?
Is the reaction endothermic or exothermic?
What is the enthalpy change for the dissolution of the 14.0 grams of KOH?
In a coffee cup calorimeter, 100.0 mL of 1.0 M NaOH and 100.0 mL of 1.0 M HCl are mixed. Both solutions were originally at 24.6°C. After the reaction, the final temperature is 31.3°C. Assuming that all solutions have density of 1.0g/cm3 and a specific heat capacity of 4.184 J/g°C, calculate the enthalpy change for the neutralization of HCl by NaOH. Assume that no heat is lost to the surroundings or the calorimeter.
Substance ΔHf° (kJ/mol)
NH4ClO4(s) -295
Al2O3(s) -1676
AlCl3(s) -704
NO(g) 90.0
H2O(g) -242
Given the information above, calculate the ΔHrxn for the following chemical reaction.
3 Al(s) + 3 NH4ClO4(s) → Al2O3(s) + AlCl3(s) + 3 NO(g) + 6 H2O(g)
The heat of combustion for the gasses hydrogen, methane and ethane are −285.8, −890.4 and −1559.9 kJ/mol respectively at 298 K. Calculate (at the same temperature) the heat of reaction for the following reaction:
2 CH4(g) → C2H6(g) + H2(g)
Calculate the change in energy that accompanies the following reaction given the data below.
H2(g) + F2(g) → 2 HF(g)
Bond Type Bond Energy
H—H 432 kJ/mol
F—F 154 kJ/mol
H—F 565 kJ/mol