Chem Engineer Study 08

What is the enthalpy for reaction 1 reversed?: Reversed: 2NO + O2→2NO2

-109 kJ/mol

Calculate the enthalpy of the reaction 2NO(g)+O2(g)→2NO2(g) given the following reactions and enthalpies of formation: 1/2N2(g)+O2(g)→NO2(g) ΔH∘A=33.2 kJ 1/2N2(g)+12O2(g)→NO(g) ΔH∘B=90.2 kJ

-114 kJ

Calculate the enthalpy change for the reaction P4O6(s)+2O2(g)→P4O10(s) given the following enthalpies of reaction: P4(s)+3O2(g)→P4O6(s) ΔH=−1640.1kJ P4(s)+5O2(g)→P4O10(s) ΔH=−2940.1kJ

-1300 kJ

From the enthalpies of reaction H2(g)+F2(g)→2HF(g) ΔH=−537kJ C(s)+2F2(g)→CF4(g) ΔH=−680kJ 2C(s)+2H2(g)→C2H4(g) ΔH=+52.3kJ calculate ΔH for the reaction of ethylene with F2:C2H4(g)+6F2(g)→2CF4(g)+4HF(g)

-2486 kJ

Calculate the enthalpy of the reaction 4B(s)+3O2(g)→2B2O3(s) given the following pertinent information: 1) B2O3(s)+3H2O(g)→3O2(g)+B2H6(g), ΔH∘A=+2035 kJ 2) 2B(s)+3H2(g)→B2H6(g) ΔH∘B=+36 kJ 3) H2(g)+12O2(g)→H2O(l) ΔH∘C=−285 kJ 4) H2O(l)→H2O(g) ΔH∘D=+44 kJ

-2552 kJ

When a 6.50-g sample of solid sodium hydroxide dissolves in 100.0 g of water in a coffee-cup calorimeter (the following Figure), the temperature rises from 21.6 ∘C to 37.8 ∘C. Calculate ΔH (in kJ/mol NaOH) for the solution process NaOH(s)→Na+(aq)+OH−(aq) Assume that the specific heat of the solution is the same as that of pure water.

-44.4 kJ/mol

From the enthalpies of reaction 2C(s)+O2(g)→2CO(g) ΔH=−221.0kJ 2C(s)+O2(g)+4H2(g)→2CH3OH(g) ΔH=−402.4kJ calculate ΔH for the reaction CO(g)+2H2(g)→CH3OH(g)

-90.7 kJ

A 100.0 -g bar of gold is heated from 25 ∘C to 50 ∘C during which it absorbs 322 J of heat. Assume the volume of the gold bar remains constant. Based on the data, calculate the specific heat of Au(s).

.13 J/(g x *C)

For a given sample of CH3OH, the enthalpy change during the reaction is 82.5 kJ . How many grams of methane gas are produced?

10.5 g

Given the data N2(g)+O2(g) → 2NO(g) ΔH=+180.7kJ 2NO(g)+O2(g) → 2NO2(g) ΔH=−113.1kJ 2N2O(g) → 2N2(g)+O2(g) ΔH=−163.2kJ use Hess's law to calculate ΔH for the reaction N2O(g)+NO2(g)→3NO(g)

155.7 kJ

How many grams of MgO are produced during an enthalpy change of -239 kJ ?

16 g

What is the molar heat capacity of Au(s)?

25 J/(mol x *C)

When a 4.25-g sample of solid ammonium nitrate dissolves in 60.0 g of water in a coffee-cup calorimeter, the temperature drops from 22.0 ∘C to 16.9 ∘C. Calculate ΔH (in kJ/mol NH4NO3) for the solution process NH4NO3(s)→NH4+(aq)+NO3−(aq) Assume that the specific heat of the solution is the same as that of pure water.

26 kJ/mol

In the following experiment, a coffee-cup calorimeter containing 100 mL of H2O is used. The initial temperature of the calorimeter is 23.0 ∘C. If 2.70 g of CaCl2 is added to the calorimeter, what will be the final temperature of the solution in the calorimeter? The heat of solution ΔHsoln of CaCl2 is l−82.8 kJ/mol.

27.7 *C

How many kilojoules of heat are released when 38.7 g of CH4(g) reacts completely with O2(g) to form CH3OH(g) at constant pressure?

305 kJ

The specific heat of octane, C8H18(l), is 2.22 J/g⋅K. How many J of heat are needed to raise the temperature of 90.0 g of octane from 10.2 ∘C to 25.6 ∘C?

3080 J

How many kilojoules of heat are absorbed when 40.5 g of MgO(s) is decomposed into Mg(s) and O2(g) at constant pressure?

605 kJ

What is the enthalpy for the following reaction? overall: N2O4→2NO2

63 kJ/mol

Calculate the amount of heat transferred when 22.0 g of CH3OH(g) is decomposed by this reaction at constant pressure.

86.8 kJ

Calculate the amount of heat transferred when 3.55 g of Mg(s) reacts at constant pressure.

87.9 kJ

Which will require more heat, increasing the temperature of 1 mol of C8H18(l) by a certain amount or increasing the temperature of 1 mol of H2O(l) by the same amount?

Increasing the temperature of 1 mol of C8H18(l) by a certain amount

Suppose that the same amount of heat is added to two 10.0-g blocks of metal, both initially at the same temperature. One block is gold metal and one is iron metal. Which block will have the greater rise in temperature after the addition of the heat?

The gold block have the higher final temperature.

Consider the following reaction: 2CH3OH(g)→2CH4(g)+O2(g)ΔH=+252.8kJ Is this reaction exothermic or endothermic?

endothermic

Is this process endothermic or exothermic?

endothermic

Consider the following reaction: 2Mg(s)+O2(g)→2MgO(s)ΔH= −1204kJ Is this reaction exothermic or endothermic?

exothermic

The equations given in the problem introduction can be added together to give the following reaction: overall: N2O4→2NO2 However, one of them must be reversed. Which one?

reaction 1: 2NO2→2NO + O2