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9.103 One reason why the energy density of a fuel is important is that to move a vehicle one must also move its unburned fuel. Octane is a major component of gasoline. It burns according to the reaction
Starting from this thermochemical equation, describe how you would determine the energy density, in kJ/g, for octane. Be sure to indicate what you would need to calculate or look up to complete this problem.
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- 9.41 Under what conditions does the enthalpy change equal the heat of a process?arrow_forwardA 10.00-g sample of acetic acid, HC2H3O2, was burned in a bomb calorimeter in an excess of oxygen. HC2H3O2(l)+2O2(g)2CO2(g)+2H2O(l) The temperature of the calorimeter rose from 25.00C to 35.84C. If the heat capacity of the calorimeter and its contents is 13.43 kJ/C, what is the enthalpy change for the reaction?arrow_forwardGiven the following (hypothetical) thermochemical equations: A+B2C;H=447kJA+3D2E;H=484kJ2D+B2F;H=429kJ Calculate H, in kJ, for the equation 4E+5B4C+6Farrow_forward
- Hydrogen peroxide, H2O2, is a colorless liquid whose solutions are used as a bleach and an antiseptic. H2O2 can be prepared in a process whose overall change is H2(g)+O2(g)H2O2(l) Calculate the enthalpy change using the following data: H2O2(l)H2O(l)+12O2(g);H=98.0kJ2H2(g)+O2(g)2H2O(l);H=571.6kJarrow_forwardHydrogen sulfide, H2S, is a poisonous gas with the odor of rotten eggs. The reaction for the formation of H2S from the elements is H2(g)+18S3(rhombic)H2S(g) Use Hesss law to obtain the enthalpy change for this reaction from the following enthalpy changes: H2S(g)+32O2(g)H2O(g)+SO2(g);H=518kJH2(g)+12O2(g)H2O(g);H=242kJ18S8(rhombic)+O2(g)SO2(g);H=297kJarrow_forwardA 0.470-g sample of magnesium reacts with 200 g dilute HCl in a coffee-cup calorimeter to form MgCl2(aq) and H2(g). The temperature increases by 10.9 C as the magnesium reacts. Assume that the mixture has the same specific heat as water and a mass of 200 g. (a) Calculate the enthalpy change for the reaction. Is the process exothermic or endothermic? (b) Write the chemical equation and evaluate H.arrow_forward
- The thermochemical equation for the burning of methane, the main component of natural gas, is CH4(g)+2O2(g)CO2(g)+2H2O(l)H=890kJ (a) Is this reaction endothermic or exothermic? (b) What quantities of reactants and products are assumed if H = 890 kJ? (c) What is the enthalpy change when 1.00 g methane burns in an excess of oxygen?arrow_forwardWhen solid iron burns in oxygen gas (at constant pressure) to produce Fe2O3(s), 1651 kJ of heat is released for every 4 mol of iron burned. How much heat is released when 10.3 g Fe2O3(s) is produced (at constant pressure)? What additional information would you need to calculate the heat released to produce this much Fe2O3(s) if you burned iron in ozone gas, O3(g), instead of O2(g)?arrow_forward9.73 Without looking up any numerical data or doing calculations, predict whether the enthalpy change for each of the following reactions should he positive, negative, or zero. (a) H2O(l)H2O(s) (b) N2(g)2N(g) (c) CH4(g)+2O2(g)CO2(g)+2H2O(l) (d) CO2(s)CO2(g)arrow_forward
- Is the following reaction the appropriate one to use in determining the enthalpy of formation of methane, CH4(g)? Why or why not? C(g)+4H(g)CH4(g)arrow_forwardWhat mass of acetylene, C2H2(g), must be burned to produce 3420 kJ of heat, given that its enthalpy of combustion is 1301 kJ/mol? Compare this with the answer to Exercise 5.91 and determine which substance produces more heat per gram.arrow_forwardA typical fat in the body is glyceryl trioleate, C57H104O6. When it is metabolized in the body, it combines with oxygen to produce carbon dioxide, water, and 3.022104 kJ of heat per mole of fat. (a) Write a balanced thermochemical equation for the metabolism of fat. (b) How many kilojoules of energy must be evolved in the form of heat if you want to get rid of five pounds of this fat by combustion? (c) How many nutritional calories is this? (1 nutritional calories =1103 calories)arrow_forward
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