How much heat in kilojoules is evolved or absorbed in each of the following reactions?
- (a) Burning of 15.5 g of propane:
- (b) Reaction of 4.88 g of barium hydroxide octahydrate with ammonium chloride:
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General Chemistry: Atoms First
- A 50-mL solution of a dilute AgNO3 solution is added to 100 mL of a base solution in a coffee-cup calorimeter. As Ag2O(s) precipitates, the temperature of the solution increases from 23.78 C to 25.19 C. Assuming that the mixture has the same specific heat as water and a mass of 150 g, calculate the heat q. Is the precipitation reaction exothermic or endothermic?arrow_forwardNitric acid, HNO3, can be prepared by the following sequence of reactions: 4NH3(g)+5O2(g)4NO(g)+6H2O(g)2NO(g)+O2(g)2NO2(g)3NO2(g)+H2O(l)2HNO3(l)+NO(g) How much heat is evolved when 1 mol of NH3(g) is converted to HNO3(l)? Assume standard states at 25 C.arrow_forward9.53 Using these reactions, find the standard enthalpy change for the formation of 1 mol of PhO(s) from lead metal and oxygen gas. PbO(s)+C(graphite)Pb(s)+CO(g) H = 106.8 kJ 2C(graphite)+O2(g)2CO(g) H= -221.0 kJ If 250 g of lead reacts with oxygen to form lead(II) oxide, what quantity of thermal energy (in kJ) is ahsorhed or evolved?arrow_forward
- Hydrogen cyanide is used in the manufacture of clear plastics such as Lucite and Plexiglas. It is prepared from ammonia and natural gas (CH4). 2NH3(g)+3O2(g)+2CH4(g)2HCN(g)+6H2O(g) The reaction evolves 469 kJ of heat per mol of HCN formed. Is the reaction endothermic or exothermic? What is the value of q when 2 mol HCN forms?arrow_forwardAnother reaction that is used to propel rockets is N2O4(l)+2N2H4(l)3N2(g)+4H2O(g) This reaction has the advantage that neither product is toxic, so no dangerous pollution is released. When the reaction consumes 10.0 g liquid N2O4, it releases 124 kJ of heat. (a) Is the sign of the enthalpy change positive or negative? (b) What is the value of H for the chemical equation if it is understood to be written in molar quantities?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_forward
- The head of a strike anywhere match contains tetraphosphorus trisulfide, P4S3. In an experiment, a student burned this compound in an excess of oxygen and found that it evolved 3651 kJ of heat per mole of P4S3 at a constant pressure of 1 atm. She wrote the following thermochemical equation: P4S3(s)+8O2(g)P4O10(s)+3SO2(g);H=3651kJ Calculate the standard enthalpy of formation of P4S3, using this students result and the following standard enthalpies of formation: P4O10(s), 3009.9 kJ/mol; SO2(g), 296.8 kJ/mol. How does this value compare with the value given in Appendix C?arrow_forwardGiven 2Al2O3(s)4Al(s)+3O2(g)H=3351.4kJ (a) What is the heat of formation of aluminum oxide? (b) What is H for the formation of 12.50 g of aluminum oxide?arrow_forwardGiven 2Cr2O3(s)4Cr(s)+3O2(g)H=+2269.4kJ (a) What is the heat of formation of chromium(III) oxide? (b) What is H for the formation of 13.65 g of chromium (III) oxide?arrow_forward
- Combustion of table sugar produces CO2(g) and H2O( l). When 1.46 g table sugar is combusted in a constant-volume (bomb) calorimeter, 24.00 kJ of heat is liberated. a. Assuming that table sugar is pure sucrose, C12H22O11 (s), write the balanced equation for the combustion reaction. b. Calculate E in kJ/mol C12H22O11 for the combustion reaction of sucrose.arrow_forwardAlloys When a 58.8-g piece of hot alloy is placed in125 g of cold water in a calorimeter, the temperature ofthe alloy decreases by 106.1°C, while the temperature ofthe water increases by 10.5°C. What is the specific heat ofthe alloy?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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