Question

1. 2C₈H₁₈   + 25O₂ → 16CO₂ + 18H₂O      
   ΔH° rxn = -11020 kJ/mol rxn
   Look at above equation. How many kJ of heat will be released when 7.00 grams of C₈H₁₈  is combusted?
2. Which of the following would be endothermic ?

		2Na + Cl2    ---> 2NaCl
		CH4 + 2O2 --> CO2 + 2H2O
		changing a solid iron nail to molten iron by melting it
		an iron nail rusts
		paper burns

3. The sign of ∆H for the process NaCl( s) --> NaCl( l) is
4. When 1.0 mole of ZnO changes into pure Zinc and oxygen, the ΔH = 348 kJ. What does this tell you about the reaction?
5. When pure hydrogen and fluorine change into HF, the reaction releases heat. What does this tell you about the reaction? the sign of ∆H for the process Fe( s)     Fe( l) is (hint--what do you have to do to melt iron?

Answer 1

The chemical equation is 268 Hip +2502 - 1620, +18 H20 AH = -11020kJ moi The reaction tells, when a moles of C8 H18 get to then - 1120k I mol of heat released. 2 moles of his release == 11020 kJ. 1 mole of Cg Hig releure = -11020 kJ. 225 510k] .30H Molecular weight of eg H18 = 114 gmoi · 114g of Cq Hiq = 1 amole - Ig of Cg Hig = 1149 mole . 79 of Cg Hg = 1 x 78 mon = 0.0614! mel. : 1 mole of Cq Hg release =-5510 KJ 1.0.0614 mole of Cq Hg release =-5510 000614 kJ = -338.39 *J. 1149 ,

* The changing a solid iron nail te molten inon by melting it - Endothermic process Because to change solid inon to molten inon, we have to break the intermoleculan fonce. among the molecule on which required energy. That means energy is consumed in the process, * Nuel(s) - Nuel (1) AH = tve.

* when a mole of and changes into pure zine and onggen the al = 348KJ. This means the - 348kJ. This means the process consume by to break zno te pune zinco and orggen. The port ess is endothermic. when pure hydrogen and fluonine changes to HF, the reaction releases heat. This means the reaction is Enothermic. * Fe(s) - Fe (1) alt=tve The process is endothermic, because te convent solid Fe to liquid Fe, we have to break the inter- molecular foney among the molecules, which required enengy