Question 2. A homeowner uses 4.00 x 103 m3 of natural gas in a year to heat ahome. Assume that natural gas is all methane, CH4, and that methane is aperfect gas for the conditions of this problem, which are 1.00 atm and20°C. What is the mass of gas used?

Natural gas companies in the United States use the therm as a unit of energy. One therm is 1105 BTU. (a) How many joules are in one therm? (1J=9.48104BTU) (b) When propane gas, C3H8, is burned in oxygen, CO2 and steam are produced. How many therms of energy are given off by 1.00 mol of propane gas?

On complete combustion at constant pressure, a 1.00-L sample of a gaseous mixture at 0C and 1.00 atm (STP) evolves 75.65 kJ of heat. If the gas is a mixture of ethane (C2H6) and propane (C3H8), what is the mole fraction of ethane in the mixture?

Chlorine dioxide, ClO2, is a reddish yellow gas used in bleaching paper pulp. The average speed of a ClO2 molecule at 25C is 306 m/s. What is the kinetic energy (in joules) of a ClO2 molecule moving at this speed?

Acetic acid, HC2H3O2, is the sour constituent of vinegar (acetum is Latin for vinegar). In an experiment, 3.58 g of acetic acid was burned. HC2H3O2(l)+2O2(g)2CO2(g)+2H2O(l) If 52.0 kJ of heat evolved, what is H per mole of acetic acid?

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?

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.

A 45-g aluminum spoon (specific heat 0.88 J/g C) at 24 C is placed in 180 mL (180 g) of coffee at 85 C and the temperature of the two become equal. (a) What is the final temperature when the two become equal? Assume that coffee has the same specific heat as water. (b) The first time a student solved this problem she got an answer of 88 C. Explain why this is clearly an incorrect answer.

How much heat, in joules and in calories, is required to heat a 28.4-g (1-oz) ice cube from 23.0 C to 1.0 C?

How much heat, in joules and in calories, must be added to a 75.0g iron block with a specific heat of 0.449 Jig C to increase its temperature from 25 C to its melting temperature of 1535 C?