0
When one mole of benzene C6H6 is burned in O2 to produce CO2 and H2O capital deltaH -3300 kJ. What is capital deltaH for 12 CO2 6 H2O right arrow 2 C6H6 15 O2?
Feartheturtle17
ΔH = sum of standard enthalpies of formation of products - sum of standard enthalpies of formation of reactats ΔH = [ 12 X ΔHf for CO2 + 6 X ΔHf for H2O ] - [ 2 X ΔHf for C6H6 + 15 X ΔHf for O2 ] ΔHf for CO2 = -393.5 ΔHf for H2O = -285.8 ΔHf for C6H6 = 48.95 ΔHf for O2 = 0 so putting the values... ΔH = [ 12 X -393.5 + 6 X -285.8 ] - [ 2 X 48.95 + 15 X 0 ] ΔH = [ -4722 - 1714.8 ] - [ 97.9 + 0 ] ΔH = -6436.8 -97.9 = -6534.7 kj so 6534.7 kj of heat is obtained by combusting 2 mole of benzene.... or in other words 6534.7 kj of heat is obtained by combusting 78 X 2 = 156 g of benzene.. so 1 kj of heat will be obtained by 156/6534.7 g of benzene... so 2570 kj of heat will be obtained by 156/6534.7 X 2570 = 61.352 g of benzene... second question ----- 2C2H6 + 7O2 -----> 4CO2 + 6H2O ...ΔH = -3119.7 kj ...(1) 2H2 + O2 -----> 2H2O ...ΔH = -478.84 kj ......(2) 2CO + O2 ----> 2CO2 ...ΔH = -565.98 ....(3) and you have to calculate delta H for the following reaction ... C2H6 + O2 ------> 3H2 + 2CO multiply equation (2) by 3 6H2 + 3O2 -----> 6H2O ...ΔH = -478.84 X 3= -1436.52 kj 6H2 + 3O2 ----> 6H2O ...ΔH = -1436.52 kj ....(4) multiply equation (3) by 2... 4CO + 2O2 -----> 4CO2 ....ΔH = 2 X -565.98 = -1131.96 kj 4CO + 2O2 ----> 4CO2 ...ΔH = -1131.96 kj ....(5) add equation (4) and equation (5).. 6H2 + 3O2 + (4CO + 2O2) ----> 6H2O + 4CO2 ....ΔH = -1436.52 + (-1131.96) = -2568.48 6H2 + 4CO + 5O2 -----> 6H2O + 4CO2 ...ΔH = -2568.48 kj....(6) subtracting equation (1) from equation (6) 2C2H6 + 7O2 - (6H2 + 4CO + 5O2) -------> 4CO2 + 6H2O - (6H2O + 4CO2) ..ΔH = -3119.7 - (-2568.48) = -3119.7 + 2568.48 = -551.22 kj 2C2H6 + 2O2 -6H2 -4CO ------> 4CO2 - 4CO2 + 6H2O - 6H2O ..ΔH = -551.22 kj 2C2H6 + 2O2 ------> 6H2 + 4CO...ΔH = -551.22 kj ..(7) dividing equation (7) by 2 C2H6 +O2 -----> 3H2 + 2CO ...ΔH = -551.22/2 = -275.61 hence ΔH for C2H6 + O2 -----> 3H2 + 2CO is -275.61 kj
Wiki User
∙ 9y ago
Add your answer:
Earn +20 pts
On what conditions does a spontaneous reaction become spontaneous?
For some non-spontaneous reactions, you can change the temperature. For other non-spontaneous reactions, there is nothing you can do to make it spontaneous. Nature favors reactions that increase a system's entropy (disorder) and nature favors reactions that are exothermic (they release enthalpy). Any reaction that does both of these things is spontaneous at all temperatures. Any reaction that does neither of these things is never spontaneous. As far as this question is concerned, the interesting reactions are endothermic reactions that increase entropy and exothermic reactions that decrease entropy. Whether these reactions are spontaneous depends on the temperature. The first variety (endothermic, increase entropy) will be spontaneous at high temperatures; the second (exothermic, decrease entropy) will be spontaneous at low temperatures. To find the temperature at which a reaction becomes spontaneous, one may apply the Gibbs equation: DG = DH - TDS where capital Ds stand for the Greek capital delta.
What happens to the temperature during an endothermic reaction?
When a endothermic reaction happens, you may be able to notice a drop in temperature. Sometimes, endothermic reactions need more energy than they can get from their surroundings. In those cases, energy must be added as heat to cause the reaction to take place.Hope this helps.
What happens when clch2ch2sch2ch2cl hits humans please give the formula also please help with deltah of the rxn?
The sulfur mustards, or also known as mustard gas(1,5-dichloro-3-thiapentane) is a member, are a class of related cytotoxic, vesicant chemical warfare agents with the ability to form largeblisters on exposed skin. Pure sulfur mustards are colorless, viscous liquids at room temperature. However, when used in impure form, such as warfare agents, they are usually yellow-brown in color and have an odor resembling mustard plants, garlic or horseradish, hence the name. Mustard gas was originally assigned the name LOST, after Lommel and Steinkopf, who first proposed the military use of sulfur mustard to the German Imperial General Staff in 1916Soldier with moderate mustard gas burns sustained during World War Ishowing characteristic bullae on neck, armpit and hands
What is a chemical reaction at equilibrium?
deltaG = deltaH -TdeltaS. deltaG = 0 at equilibrium. Therefore deltaH = TdeltaS
What does a negative deltaH tell about a reaction?
the reaction is exothermic
Which of the following is endothermic a dry ice evaporating b a sparkler burning c the reaction that occurs in a chemical cold pack often used to ice athletic injuries?
Dry ice evaporating is endothermic-->+DeltaH A sparkler burning is exothermic--->-DeltaH The reaction that occurs in a chemical cold pack often used to ice athletic injuries is endothermic--->+DeltaH
How can an unknown deltaH reaction be determined using Hess's law?
Enthalpies from reaction steps are added to determine an unknownHreaction.
What are the different types of calorimeters?
Bomb calorimeter and coffee-cup calorimeter. Both useful, however, the bomb calorimeter is better to use if you're measuring deltaH of a gas
What is the balanced chemical equation Nabh4 plus h20 yield NaBo plus h2?
NaBH4 + 2H2O -> NaBO2 + 4H2 [1] DeltaG(298K)= -299 kJ/mol BH4 DeltaH(298K)= -231 kJ/mol BH4 (10.8 mass% H) NaBH4 + 4H2O -> NaB(OH)4 + 4H2 [2] DeltaG (298K)= -315 kJ/mol BH4 DeltaH = -247 kJ/mol BH4 (7.28 mass% H) NaBH4 + 6H2O -> NaB(OH)4.2H2O [3] DeltaG = -319kJ/mol BH4 DeltaH = -213 kJ/mol BH4 (5.48 mass% H) *Hydrolysis in Eq.[1] is not the most favorable reaction!
Is baking soda and citric acid a endothermic or exothermic reaction?
It is endothermic. The heat of the water in the calorimeter decreases (giving you a -deltaH), which means that the system absorbed heat, making the reaction endothermic.
When food goes into a eukaryotic cell what does it do?
Food is decomposed to glucose which is then; through a lot of reactions, made into carbon dioxide and water C6H12O6(glucose)+6O2(oxygen)------->6CO2(carbondioxide)+6H2O(water) deltaH=-2941 kJ/mol
The reaction between strontium metal and chlorine gas is described by the following thermochemical equation Sr s Cl2 g plus SrCl2 s deltaH -829 kJ mol-1 What will be the enthalpy change to 2 sig figs?
-830
What important information does a thermochemical equation have that a regular balanced equation does not?
A thermochemical equation shows the amount of heat given out or taken in when the reaction occurs. CH4 + 2O2 = CO2 +2H2O, deltaH = -890 kJ/mol Note delta H is negative when heat is given out, exothermic and +ve when endothermic. Sorry can't do delta symbol - its a triangle!
What important information does thermochemical equation have that a regular balanced equations does not?
A thermochemical equation shows the amount of heat given out or taken in when the reaction occurs. CH4 + 2O2 = CO2 +2H2O, deltaH = -890 kJ/mol Note delta H is negative when heat is given out, exothermic and +ve when endothermic. Sorry can't do delta symbol - its a triangle!
What would form a spontaneous reaction at 298 K?
deltaH=28 kJ/mol, deltaS=0.109 kJ(molK)
