The specific heat of ethanol, C₂H₅OH(l), is 2.44 J•g/K. (a) How many J of heat are needed to raise the temperature of 80.0 g of octane from 10.0 to 25.0 °C?

The specific heat of ethanol, C₂H₅OH(l), is 2.44 J•g/K. b. Which will require more heat, increasing the temperature of 1 mol of C₂H₅OH(𝑙) by a certain amount or increasing the temperature of 1 mol of H₂O(𝑙) by the same amount?

Consider the data about gold metal in Exercise 5.24(b). b. 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 the other is iron metal. Which block will have the greater rise in temperature after addition of the heat?

Consider the data about gold metal in Exercise 5.24(b). c. What is the molar heat capacity of Au(s)?

When a 5.10-g sample of solid sodium hydroxide dissolves in 100.0 g of water in a coffee-cup calorimeter (Figure 5.18), the temperature rises from 20.5 to 33.2 °C. a. Calculate the quantity of heat (in kJ) released in the reaction.

When a 5.10-g sample of solid sodium hydroxide dissolves in 100.0 g of water in a coffee-cup calorimeter (Figure 5.18), the temperature rises from 20.5 to 33.2 °C. b. Using your result from part (a), calculate ΔH (in kJ/mol NaOH) for the solution process. Assume that the specific heat of the solution is the same as that of pure water.

(b) Is this process endothermic or exothermic?

A 2.200-g sample of quinone (C₆H₄O₂) is burned in a bomb calorimeter whose total heat capacity is 7.854 kJ/°C. The temperature of the calorimeter increases from 23.44 to 30.57 °C. (a) What is the heat of combustion per gram of quinone?

A 2.200-g sample of quinone (C₆H₄O₂) is burned in a bomb calorimeter whose total heat capacity is 7.854 kJ/°C. The temperature of the calorimeter increases from 23.44 to 30.57 °C. b. What is the heat of combustion per mole of quinone?

A 1.800-g sample of phenol (C₆H₅OH) was burned in a bomb calorimeter whose total heat capacity is 11.66 kJ/°C. The temperature of the calorimeter plus contents increased from 21.36 to 26.37 °C. a. Write a balanced chemical equation for the bomb calorimeter reaction.

A 1.800-g sample of phenol (C6H5OH) was burned in a bomb calorimeter whose total heat capacity is 11.66 kJ/°C. The temperature of the calorimeter plus contents increased from 21.36 to 26.37 °C. b. What is the heat of combustion per gram of phenol?

Under constant-volume conditions, the heat of combustion of benzoic acid (C₆H₅COOH) is 26.38 kJ/g. A 2.760-g sample of benzoic acid is burned in a bomb calorimeter. The temperature of the calorimeter increases from 21.60 to 29.93 °C. c. Suppose that in changing samples, a portion of the water in the calorimeter were lost. In what way, if any, would this change the heat capacity of the calorimeter?

Consider the following hypothetical reactions: A → B ΔH = +30 kJ B → C ΔH = +60 kJ (b) Construct an enthalpy diagram for substances A, B, and C, and show how Hess's law applies.

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

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

The concentration of alcohol 1CH3CH2OH2 in blood, called the 'blood alcohol concentration' or BAC, is given in units of grams of alcohol per 100 mL of blood. The legal definition of intoxication, in many states of the United States, is that the BAC is 0.08 or higher. What is the concentration of alcohol, in terms of molarity, in blood if the BAC is 0.08?

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

We can use Hess's law to calculate enthalpy changes that cannot be measured. One such reaction is the conversion of methane to ethane: 2 CH4(g) → C2H6(g) + H2(g) Calculate the ΔH° for this reaction using the following thermochemical data: CH4(g) + 2 O2(g) → CO2(g) + 2 H2O(l) ΔH° = -890.3 kJ 2 H2(g) + O2(g) → 2 H2O(l) H° = -571.6 kJ 2 C2H6(g) + 7 O2(g) → 4 CO2(g) + 6 H2O(l) ΔH° = -3120.8 kJ

(c) What is meant by the term standard enthalpy of formation?

What is the value of the standard enthalpy of formation of an element in its most stable form?

For each of the following compounds, write a balanced thermochemical equation depicting the formation of one mole of the compound from its elements in their standard states and then look up H °f for each substance in Appendix C. (b) FeCl₃(s)

Write balanced equations that describe the formation of the following compounds from elements in their standard states, and then look up the standard enthalpy of formation for each substance in Appendix C: (a) NH₄NO₃(s)

Many portable gas heaters and grills use propane, C₃H₈(g), as a fuel. Using standard enthalpies of formation, calculate the quantity of heat produced when 10.0 g of propane is completely combusted in air under standard conditions.

Using values from Appendix C, calculate the value of H for each of the following reactions: (a) NiO(s) + 2 HCl(g) → NiCl₂(s) + H₂O(g)

Complete combustion of 1 mol of acetone (C₃H₆O) liberates 1790 kJ: C₃H₆O(l) + 4 O₂(g) → 3 CO₂(g) + 3 H₂O(l) ΔH° = -1790 kJ Using this information together with the standard enthalpies of formation of O₂(g), CO₂(g), and H₂O(l) from Appendix C, calculate the standard enthalpy of formation of acetone.

Calcium carbide (CaC₂) reacts with water to form acetylene (C₂H₂) and Ca(OH)₂. From the following enthalpy of reaction data and data in Appendix C, calculate H°_f for CaC₂(s): CaC₂(s) + 2 H₂O(l) → Ca(OH₂)(s) + C₂H₂(g) ΔH° = -127.2 kJ

Gasoline is composed primarily of hydrocarbons, including many with eight carbon atoms, called octanes. One of the cleanest–burning octanes is a compound called 2,3,4- trimethylpentane, which has the following structural formula: The complete combustion of one mole of this compound to CO₂(g) and H₂O(g) leads to ΔH° = -5064.9 kJ. (b) By using the information in this problem and data in Table 5.3, calculate H°f for 2,3,4-trimethylpentane.

Diethyl ether, C₄H₁₀O(l), a flammable compound that was once used as a surgical anesthetic, has the structure The complete combustion of 1 mol of C₄H₁₀O(l) to CO₂(g) and H₂O(l) yields ΔH° = -2723.7 kJ. (a) Write a balanced equation for the combustion of 1 mol of C₄H₁₀O(l).

Ethanol (C₂H₅OH) is blended with gasoline as an automobile fuel. (c) Calculate the heat produced per liter of ethanol by combustion of ethanol under constant pressure. Ethanol has a density of 0.789 g/mL.