3. Find the standard enthalpy of formation of hyene enhefollowingd . given the following data: (Example 6.11 page CaH4(g)+ 302(8) 2cO-)+2H,00) All'm -14lII kI ( 241) Given thǐtardco2(g)) =-393.5 kJ/rnol ΔΗ"dH2O(1)--285.8 kJ/mol 4. Given 2Al(s) + 3/202(g) → A10;(s) AH't =-1670 kJ (Sec 6.8 Rule No I & 2) what is ΔΗ for the reaction? 3. Find the standard enthalpy of formation of hyene enhefollowingd . given the following data: (Example 6.11 page CaH4(g)+ 302(8) 2cO-)+2H,00) All'm -14lII kI ( 241) Given thǐtardco2(g)) =-393.5 kJ/rnol ΔΗ"dH2O(1)--285.8 kJ/mol 4. Given 2Al(s) + 3/202(g) → A10;(s) AH't =-1670 kJ (Sec 6.8 Rule No I & 2) what is ΔΗ for the reaction?
Ans 3 : The standard enthalpy of the reaction can be determined by subtracting the formation enthalpies of reactants from that of products. Here it is -1411 KJ , and the formation enthalpy of CO2 (g) and H2O (l) is given and that of O2 (g) is 0 putting values : -1411 = 2(-393. 5 KJ/mol) + 2(-285. 8 KJ/mol) - 3(0) - H H = 52. 4 KJ/mol
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