General Chemistry
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The reaction of two moles of compound A with one mole of O2 produces two moles of a single compound B. The mass percentages of C and O in compound B are 27.3% and 72.7%, respectively. The heat of formation of compound B is −393.52 kJ/mol. How much heat (in kJ) units is released when 12.6 g of compound A reacts with a stoichiometric amount of O2 to produce compound B? Assume that the reaction yield is 74.0%.
The term "alcohol" generally refers to the compound ethanol C2H5OH (or ethyl alcohol). The heat of vaporization for ethanol is 38.6 kJ/mol. If the combustion of ethanol is carried out in an adiabatic calorimeter, can its boiling point be measured? How much energy (in kJ units) is required to evaporate 15.4 g of ethanol at its boiling point from the liquid state to the gaseous state? The density of liquid ethanol is 0.790 g/mL.
A certain fuel mixture is made up of the following gases in percent by volume: 30.6% propane (C3H8), 52.3% butane (C4H10), and the rest pentane (C5H12). The mixture is stored at 298 K and 745 mmHg in a 2.50 L gas tank. When the fuel mixture is subjected to complete combustion, calculate the total heat that is emitted. Note that water vapor is produced in the combustion reaction.
ΔH°f (kJ/mol)C3H8(g) –103.85C4H10(g) –125.7C5H12(g) –146.9O2(g) 0CO2(g) –393.5H2O(g) –241.8
Propane (C3H8) is one of the gases that is used as fuel gas. Propane has a normal boiling point of –42.0°C and its enthalpy of vaporization is 14.79 kJ/mol. Calculate the heat that must be added to convert 300 g of propane into vapor and determine the volume of this propane gas occupies at 765 torr and 40.0°C.
If the energy from the reaction of HNO2 shown below is used to create NO2, how many moles of NO2 can be created per mole of HNO2? The energy needed to create 1.00 mol of NO2 is 122.92 kJ.
HNO2(aq) + H+(aq) + e- → NO(g) + 2 H2O(l) E° = 0.98 V
Assume that the average heat produced by the combustion of diesel is 44.80 kJ/g. Compare the energy produced by 5.0 L of diesel and 5.0 L of methanol if the heat of combustion of methanol is -726 kJ/mol. The density of diesel and methanol is 0.85 g/mL and 0.79 g/mL respectively.
Hexane (C6H14) produces 4163 kJ/mol of heat when it undergoes combustion. Calculate the heat produced by burning 5.00 gal of hexane. The density of hexane is 0.6594 g/mL.
The population of the U.S. in 2021 was 332.9 million
Assuming that glucose is metabolized entirely to carbon dioxide and water according to the following equation:
C6H12O6(s) + 6 O2(g) → 6 CO2(g) + 2 H2O(l) ΔH° = -2803 kJ
Calculate the mass of carbon dioxide in kg produced by the U.S. population in 2021 if an average person consumes 2000 Cal per day.
A tree absorbs approximately 25 kg of CO2 per year. Calculate the average energy stored by photosynthesis in a tree per year assuming that all this carbon is converted into glucose.
The following reaction shows the formation of ammonia:
N2(g) + 3 H2(g) → 2 NH3(g) ΔH°rxn = -92.00 kJ
Calculate the amount of heat required in kJ if 55.60 g of NH3 decomposes to N2 and H2 at constant pressure.
H2(g) and Cl2(g) were placed in a sealed container and allowed to react and produce HCl(g). 2.3 mol of each gas was placed in the container initially at 23.2 °C. Determine the temperature of HCl. Assume no heat is lost to the surroundings.
Calculate the mass of CO2 emitted by the combustion of pentane (C5H12) to generate 5.96 x 102 kJ of heat. The balanced reaction is shown below:
C5H12(g) + 8 O2(g) → 5 CO2(g) + 6 H2O(l) ΔH°rxn = –3509 kJ
Calculate the mass of CO2 emitted by the combustion of methanol (CH3OH) to generate 2.21 x 103 kJ of heat. The balanced reaction is shown below:
2 CH3OH(l) + 3 O2(g) → 2 CO2( g) + 4 H2O(l) ΔH°rxn = −1452.2 kJ
Butane (C4H10) used in a grill burns according to the following reaction:
2 C4H10( g) + 13 O2(g) → 8 CO2(g) + 10 H2O(g) ΔH°rxn = -5756.6 kJ
A certain piece of steak needs to absorb 539 kJ to fully cook. Calculate the mass of CO2 emitted if only 15% of the heat produced is actually absorbed by the steak.
The combustion of Nitrobenzene (C6H5NO2) is shown by the reaction below:
4 C6H5NO2(l) + 29 O2(g)→ 24 CO2(g) + 10 H2O(l) + 4 NO2(g) ΔH°rxn = -12,352 kJ
Calculate the heat generated by the complete combustion of 6.32 kg of nitrobenzene.
Solid iron reacts with O2(g) to form Fe3O4(s). The reaction from 269.3 g of iron generates enough heat to raise the temperature of 91.4 kg of water which was initially at 15.5 °C to 20.2°C. Calculate the ΔHf° Fe3O4(s).
For the neutralization of NaOH and HCl: NaOH(aq) + HCl(aq) → H2O(l) + NaCl(aq) ΔH = –57.9 kJ/mol
In a coffee cup calorimeter, 100 mL of 0.100 M NaOH was neutralized with 100 mL of 0.100 M HCl. If both solutions were initially at 25 °C, determine the final temperature of the solution. Assume that the density and heat capacity of the solution is the same as that of water.
Calculate the mass of CO(g) produced if the reaction absorbs 32.11 kJ.
CO2(g) + H2(g) → CO(g) + H2O(g) ΔH = 42 kJ
Calculate the volume of acetylene gas (C2H2) at 1 atm and 25 °C required to produce 1053.89 kJ of heat from the combustion of acetylene.
C2H2(g) + 5/2 O2(g) → 2 CO2(g) + H2O(g) ΔH°comb = –1301.1 kJ/mol
A 20.0-g sample of butane (C4H10) was combusted and the heat from the reaction was used to raise the temperature of 5.0 L of water from 25 °C to 72.37 °C. Calculate ΔH°rxn for the combustion of butane.
Lead ions can be precipitated using a solution of bromide ions: Pb2+(aq) + 2 Cl–(aq) → PbCl2(s) ΔH°f = –336.0 kJ/mol
Calculate ΔH for the formation of 5.15 g PbCl2.
The organic compound cyclobutane (C4H8) into ethylene (C2H4) according to the following equation: C4H8(g) → 2 C2H4(g); ΔH = +77.1 kJ. Calculate the ΔH for the production of 1 mole of ethylene.
Drag racing, power boats, helicopters, and planes use nitromethane (CH3NO2). The burning of CH3NO2 with oxygen is shown below:
4 CH3NO2(l) + 5 O2(g) → 4 CO2(g) + 6 H2O(g) + 4 NO(g) ΔH = –2209.2 kJ
What is the mass of the CO2 produced per kJ of heat released?
Ammonium nitrite quickly decomposes into nitrogen gas and water as shown below:
NH4NO2(s) → N2(g) + 2 H2O(l) ΔH = –315.1 kJ
Determine the ΔH for the formation of 0.118 mol of N2.
Consider the following reaction wherein lead sulfide precipitates when a solution containing lead ions and sulfide ions is mixed:
Pb2+(aq) + S2–(aq) → PbS(s) ΔH = –131.8 kJ
(a) Determine the ΔH for the formation of 0.215 mol of PbS.
(b) Determine the ΔH for the formation of 3.50 g of PbS.
(c) Determine the ΔH when 3.65×10–4 mol of PbS is dissolved in water.
Determine the ΔH for the formation of 5.60 g of H2O.
Consider the following reaction,
2 C4H10(l) + 13 O2(g) → 8 CO2(g) + 10 H2O(g) ΔH°rxn = −2877 kJ
How much natural gas (C4H10) must be burned in order to produce 356 kJ of heat?
The propane fuel (C3H8) used in gas barbeques burns according to the thermochemical equation:
C3H8(g) + 5 O2(g) → 3 CO2(g) + 4 H2O(g); ΔH°rxn = -2044 kJ
If a pork roast must absorb 1.6 x 103 kJ to be fully cooked, and if only 10% of the heat produced by the barbeque is absorbed by the roast, what mass of CO2 is emitted into the atmosphere during the grilling of the pork roast?
Determine the mass of CO2 produced by burning enough of each fuel to produce 1.00×102 kJ of heat.
a. CH4(g) + 2O2(g) → CO2(g) + 2H2O(g) ΔH°rxn = −802.3 kJ
Charcoal is primarily carbon. Determine the mass of CO2 produced by burning enough carbon (in the form of charcoal) to produce 5.00×102 kJ of heat.
C(s) + O2( g) → CO2( g) ΔH°rxn = −393.5 kJ