Thermochemistry

In carbon combustion, the oxidation of solid carbon to produce carbon monoxide is represented below:
2C(s)+O2(g)⟶2CO(g)
Use the following reaction enthalpies to find the enthalpy of the first reaction.
C(s)+O2(g)2CO2(g)→CO2(g)→2CO(g)+O2(g)ΔHΔH=−394 kJ=+283 kJ

Your answer should have three significant figures.

-505 kJ

2C(s)+O2(g)2H2(g)+O2(g)H2O(l)→2CO(g)→2H2O(g)→H2O(g)ΔHΔHΔH=−222kJ=−484kJ=+44kJ

Use the thermochemical data above to calculate the change in enthalpy for the reaction below.

H2O(l)+C(s)→CO(g)+H2(g)

Your answer should have three significant figures.

175 kJ

In the heat of formation equation for CH3CH2OH, what would be the coefficient for hydrogen gas?

3

Calculate the change in enthalpy for the reaction, given the associated enthalpies of formation.

2NO(g)+O2(g)⟶2NO2(g)ΔHf,NO2=33.2 kJΔHf,NO=90.2 kJ

Round the answer to three significant figures.

-114 kJ

Consider the reaction described by the following chemical equation.

2Ag2S(s)+2H2O(l)⟶4Ag(s)+2H2S(g)+O2(g)ΔH∘rxn=595.5kJmol

The change in enthalpy for this reaction can be determined theoretically by using the standard enthalpies of formation for the species involved.
ΔH∘rxn=∑nΔH∘fproducts−∑nΔH∘freactants

What is the value for the standard enthalpy of formation for Ag(s) that would be used in the equation above?

0 kJ/mol

Consider the following chemical equations to answer the question that follows.

CaCO3(s)Ca(OH)2(s)Ca(OH)2(s)+2HCl(g)→CaO(s)+CO2(g)→H2O(l)+CaO(s)→CaCl2(s)+2H2O(l)ΔHΔHΔH=175kJ=67kJ=−198kJ

Using the information above, determine the change in enthalpy for the following chemical reaction.

CaCO3(s)+2HCl(g)⟶CaCl2(s)+H2O(l)+CO2(g)

-90 kJ

Consider the following thermochemical equations.
PCl5 (s)→PCl3 (g)+Cl2 (g)2P (s)+3Cl2 (g)→2PCl3 (g)ΔH∘rxnΔH∘rxn=87.9kJmol=−574kJmol

Using this data, determine the heat of formation for PCl5.
Your answer should have three significant figures.

-374 kJ/mol

Calculate the change in enthalpy for the given reaction.

NaOH(s)+HCl(g)⟶NaCl(s)+H2O(g)
ΔH∘f,NaClΔH∘f,H2OΔH∘f,NaOHΔH∘f,HCl=−411.2 kJ=−241.8 kJ=−425.6 kJ=−92.3 kJ

Round your answer to one decimal place.

-135.1 kJ

If we burn a 0.545 g sample of carbon and the the enthalpy of combustion for carbon is −393.5 kJ/mol, what is the qrxn?

-17.9 kJ

If the heat of combustion of methane is −890.8 kJmol, what is the enthalpy change associated with the combustion of 1.000 kg of methane

-55,530 kJ

If the heat of combustion of carbon monoxide (CO) is −283.0 kJmole, how many grams of carbon monoxide must combust in order to release 2,500.kJ of energy?

274.2 g

The component of gasoline that gives it such a high enthalpy of combustion is:

hydrocarbons

If the heat of combustion of hydrogen gas (H2) is −285.8kJmol, how many grams of H2 must combust in order to release 1.2×103kJ of heat

8.5 g

_________ is the enthalpy change when 1 mole of a substance burns under standard state conditions.

Standard enthalpy of combustion

What is the change in enthalpy associated with the combustion of 530 g of methane (CH4)?
Report your answer in scientific notation.
Your answer should have two significant figures.
Use −890.8kJmol for the molar heat of combustion of methane.

28000 kJ

Calculate the change in enthalpy associated with the combustion of 322 g of ethanol.
Report your answer in scientific notation.
Your answer should have three significant figures.

C2H5OH(l)+3O2(g)⟶2CO2(g)+3H2O(l)ΔH∘c=−1366.8kJ/mol

-9.55 x 10^3 kJ