Zinc metal reacts with hydrochloric acid according to the balanced equation: Zn(s) + 2 HCl(aq) → ZnCl₂(aq) + H₂(g) When 0.103 g of Zn(s) is combined with enough HCl to make 50.0 mL of solution in a coffee-cup calorimeter, all of the zinc reacts, raising the temperature of the solution from 22.5 °C to 23.7 °C. Find ΔH_rxn for this reaction as written. (Use 1.0 g/mL for the density of the solution and 4.18 J/g•°C as the specific heat capacity.)

Instant cold packs used to ice athletic injuries on the field contain ammonium nitrate and water separated by a thin plastic divider. When the divider is broken, the ammonium nitrate dissolves according to the endothermic reaction: NH₄NO₃(s) → NH₄⁺(aq) + NO₃^– (aq) In order to measure the enthalpy change for this reaction, 1.25 g of NH₄NO₃ is dissolved in enough water to make 25.0 mL of solution. The initial temperature is 25.8 °C and the final temperature (after the solid dissolves) is 21.9 °C. Calculate the change in enthalpy for the reaction in kJ. (Use 1.0 g/mL as the density of the solution and 4.18 J/g•°C as the specific heat capacity.)

For each generic reaction, determine the value of ΔH₂ in terms of ΔH₁.

a. A + B → 2 C ΔH₁

2 C→ A + B ΔH₂ = ?

For each generic reaction, determine the value of ΔH₂ in terms of ΔH₁.

b. A + 1/2 B → C ΔH₁

2 A + B → 2 C ΔH₂ = ?

For each generic reaction, determine the value of ΔH₂ in terms of ΔH₁.

c. A → B + 2 C ΔH₁

1/2 B + C → 1/2 A ΔH₂ = ?

Consider the generic reaction:

A + 2 B → C + 3 D ΔH = 155 kJ

Determine the value of ΔH for each related reaction.

a. 3 A + 6 B → 3 C + 9 D

b. C + 3 D → A + 2 B

c. 1/2 C + 3/2 D → 1/2 A + B

Calculate ΔH_rxn for the reaction:

Fe₂O₃(s) + 3 CO(g) → 2 Fe(s) + 3 CO₂(g)

Use the following reactions and given ΔH's:

2 Fe(s) + 3/2 O₂(g) → Fe₂O₃(s) ΔH = –824.2 kJ

CO(g) + 1/2 O₂(g) → CO₂(g) ΔH = –282.7 kJ

Calculate ΔHrxn for the reaction:

CaO(s) + CO₂(g) → CaCO₃(s)

Use the following reactions and given ΔH's:

Ca(s) + CO₂(g) + 1/2 O2(g) → CaCO₃(s) ΔH = –812.8 kJ

2 Ca(s) + O₂(g) → 2 CaO(s) ΔH = –1269.8 kJ

Calculate ΔHrxn for the reaction:

5 C(s) + 6 H₂(g) → C₅H₁₂(l)

Use the following reactions and given ΔH's:

C₅H₁₂(l) + 8 O₂(g) → 5 CO₂(g) + 6 H₂O(g) ΔH = –3244.8 kJ

C(s) + O₂(g) → CO₂(g) ΔH = –393.5 kJ

2 H₂(g) + O₂(g) → 2 H₂O(g) ΔH = –483.5 kJ

Calculate ΔHrxn for the reaction:

CH₄(g) + 4 Cl₂(g) → CCl₄(g) + 4 HCl(g)

Use the following reactions and given ΔH's:

C(s) + 2 H₂(g) → CH₄(g) ΔH = –74.6 kJ

C(s) + 2 Cl₂(g) → CCl₄( g) ΔH = –95.7 kJ

H₂(g) + Cl₂(g) → 2 HCl( g) ΔH = –92.3 kJ

Write an equation for the formation of each compound from its elements in their standard states, and find ΔH °f for each in Appendix IIB. a. NH₃(g)

Write an equation for the formation of each compound from its elements in their standard states, and find ΔH°_rxn for each in Appendix IIB. a. NO₂(g)

Write an equation for the formation of each compound from its elements in their standard states, and find ΔH°_rxn for each in Appendix IIB. b. MgCO₃(s)

Write an equation for the formation of each compound from its elements in their standard states, and find ΔH°_rxn for each in Appendix IIB. d. CH₃OH(l)

Hydrazine (N₂H₄) is a fuel used by some spacecraft. It is normally oxidized by N₂O₄ according to the equation: N₂H₄ (l) + N₂O₄ (g) → 2 N₂O (g) + 2 H₂O (g) Calculate ΔH°_rxn for this reaction using standard enthalpies of formation.

Pentane (C₅H₁₂) is a component of gasoline that burns according to the following balanced equation: C₅H₁₂(l) + 8 O₂(g) → 5 CO₂(g) + 6 H₂O(g) Calculate ΔH°_rxn for this reaction using standard enthalpies of formation. (The standard enthalpy of formation of liquid pentane is –146.8 kJ/mol.)

Use standard enthalpies of formation to calculate ΔH°_rxn for each reaction. a. C₂H₄(g) + H₂(g) → C₂H₆(g)

Use standard enthalpies of formation to calculate ΔH°_rxn for each reaction. c. 3 NO₂(g) + H₂O(l) → 2 HNO₃(aq) + NO(g)

Use standard enthalpies of formation to calculate ΔH°_rxn for each reaction. d. Cr₂O₃(s) + 3 CO(g) → 2 Cr(s) + 3 CO₂(g)

Use standard enthalpies of formation to calculate ΔH°_rxn for each reaction. a. 2 H₂S(g) + 3 O₂(g) → 2 H₂O(l) + 2 SO₂(g)

Use standard enthalpies of formation to calculate ΔH°_rxn for each reaction. b. SO₂(g) + 1/2 O₂(g) → SO₃(g)

Use standard enthalpies of formation to calculate ΔH°_rxn for each reaction. d. N₂O₄(g) + 4 H₂(g) → N₂(g) + 4 H₂O(g)

During photosynthesis, plants use energy from sunlight to form glucose (C₆H₁₂O₆) and oxygen from carbon dioxide and water. Write a balanced equation for photosynthesis.

Ethanol (C₂H₅OH) can be made from the fermentation of crops and has been used as a fuel additive to gasoline. Write a balanced equation for the combustion of ethanol and calculate ΔH°_rxn.

Top fuel dragsters and funny cars burn nitromethane as fuel according to the balanced combustion equation: 2 CH₃NO₂(l) + 3/2O₂(g) → 2 CO₂(g) + 3 H₂O(l) + N₂(g) ΔH°_rxn = –1418 kJ The enthalpy of combustion for nitromethane is –709.2 kJ/mol. Calculate the standard enthalpy of formation (ΔH°_f ) for nitromethane.

The explosive nitroglycerin (C₃H₅N₃O₉) decomposes rapidly upon ignition or sudden impact according to the balanced equation: 4 C₃H₅N₃O₉(l) → 12 CO₂(g) + 10 H₂O(g) + 6 N₂(g) + O₂(g) ΔH°_rxn = –5678 kJ Calculate the standard enthalpy of formation (ΔH°_f ) for nitroglycerin.

Determine the mass of CO₂ produced by burning enough of each fuel to produce 1.00×10² kJ of heat. a. CH₄(g) + 2 O₂(g) → CO₂(g) + 2 H₂O(g) ΔH°_rxn = –802.3 kJ