SALT ammonium chloride ammonium nitrate FORMULA SPECIFIC HEAT (J/g°C) NH4CI 1.57 NH4NO3 1.74 ammonium sulfate (NH4)2SO4 1.409 sodium hydroxide NaOH 1.49 sodium thiosulfate pentahydrate Na2S2O3.5H2O 1.45 sodium sulfate Na2SO4 0.903 potassium bromide KBr 0.435 potassium chloride KCI 0.688 potassium hydroxide KOH 1.16 potassium nitrate KNO3 0.95

In the 1880s, Frederick Trouton noted that the enthalpy of vaporization of 1 mol pure liquid is approximately 88 times the boiling point, Tb, of the liquid on the Kelvin scale. This relationship is called Troutons rule and is represented by the thermochemical equation liquid gas H = 88 Tb, joules Combined with an empirical formula from chemical analysis, Troutons rule can be used to find the molecular formula of a compound, as illustrated here. A compound that contains only carbon and hydrogen is 85.6% C and 14.4% H. Its enthalpy of vaporization is 389 J/g, and it boils at a temperature of 322 K. (a) What is the empirical formula of this compound? (b) Use Troutons rule to calculate the approximate enthalpy or vaporization or one mole of the compound. Combine the enthalpy of vaporization per mole with that same quantity per gram to obtain an approximate molar mass of the compound. (c) Use the results of parts (a) and (b) to find the molecular formula of this compound. Remember that the molecular mass must be exactly a whole-number multiple of the empirical formula mass, so considerable rounding may be needed.

Ethyl alcohol, C2H5OH, is the intoxicating agent in liquor. Burning 1.00 g of ethyl alcohol in an excess of oxygen at 23.28C and constant volume releases 29.52 kJ of heat. When 7.40 g of ethyl alcohol is burned in oxygen under the same conditions in a bomb calorimeter, the temperature of the bomb and water rises from 23.28C to 48.04C. The bomb holds 0.750 kg of water. (a) What is q for the combustion of the ethyl alcohol in the bomb calorimeter? (b) What is qH2O? (c) What is qcal? (d) What is the heat capacity of the calorimeter?

The specific heat of copper metal was determined by putting a piece of the metal weighing 35.4 g in hot water. The quantity of heat absorbed by the metal was calculated to be 47.0 J from the temperature drop of the water. What was the specific heat of the metal if the temperature of the metal rose 3.45C?

9.104 An engineer is using sodium metal as a cooling agent in a design because it has useful thermal properties. Looting up the heat capacity, the engineer finds a value of 28.2 J mol-l °C-l. Carelessly, he wrote this number down without units. As a result, it was later taken as specific heat. (a) What would he the difference between these two values? (b) Would the engineer overestimate the ability of sodium to remove heat from the system or underestimate it because of this error? Be sure to explain your reasoning.

In 2010, 3.30109 gallons of gasoline were consumed in the United States. The following assumptions can be made: • Gasoline is mainly n-octane, C8H18(d=0.7028g/mL). • Burning one mole of n-octane in oxygen releases 5564.2 kJ of heat. • The heat capacity C of the surface region of the earth is 2.61023 J/K. What is the increase in temperature of the surface region of the earth due to gasoline consumption in the United States?

A 21.3-mL sample of 0.977 M NaOH is mixed with 29.5 mL of 0.918 M HCl in a coffee-cup calorimeter (see Section 6.6 of your text for a description of a coffee-cup calorimeter). The enthalpy of the reaction, written with the lowest whole-number coefficients, is 55.8 kJ. Both solutions are at 19.6C prior to mixing and reacting. What is the final temperature of the reaction mixture? When solving this problem, assume that no heat is lost from the calorimeter to the surroundings, the density of all solutions is 1.00 g/mL, the specific heat of all solutions is the same as that of water, and volumes are additive.

Consider the reaction 2HCl(aq)+Ba(OH)2(aq)BaCl2(aq)+2H2O(l)H=118KJ Calculate the heat when 100.0 rnL of 0.500 M HCl is mixed with 300.0 mL of 0.100 M Ba(OH)2 Assuming that the temperature of both solutions was initially 25.0C and that the final mixture has a mass of 400.0 g and a specific heat capacity of 4.18 J/C g, calculate the final temperature of the mixture.

Equal masses of liquid A, initially at 100C, and liquid B, initially at 50C, are combined in an insulated container. The final temperature of the mixture is 80C. All the heat flow occurs between the two liquids. The two liquids do not react with each other. Is the specific heat of liquid A larger than, equal to, or smaller than the specific heat of liquid B?

When one mol of KOH is neutralized by sulfuric acid, q=56 kJ. (This is called the heat of neutralization.) At 23.7C, 25.0 mL of 0.475 M H2SO4 is neutralized by 0.613 M KOH in a coffee-cup calorimeter. Assume that the specific heat of all solutions is 4.18J/gC, that the density of all solutions is 1.00 g/mL, and that volumes are additive. (a) How many mL of KOH is required to neutralize H2SO4? (b) What is the final temperature of the solution?