I have ONE question for homework that is separated intodifferent parts.
1)
a) Assume that the kinetic energy of a 1300 kg car moving at 120km/h could be converted entirely into heat.
What amount of water could be heated from 21 ∘C to 51 ∘C by thecar's energy?
b) Regarding the water in the car how much heat (in kilojoules)is evolved or absorbed in the reaction of 2.50 g of Na withH2O?
2Na(s)+2H2O(l)→2NaOH(aq)+H2(g)ΔH∘ = -368.4kJ.
c) Instant cold packs used to treat a person injured in a caraccident contain solid NH4NO3 and a pouch of water. When the packis squeezed, the pouch breaks and the solid dissolves, lowering thetemperature because of the endothermic reaction
NH4NO3(s)+H2O(l)→NH4NO3(aq)ΔH= +25.7 kJ.
What is the final temperature in a squeezed cold pack thatcontains 44.0 g of NH4NO3 dissolved in 125 mL of water on a personwho suffered a car accident? Assume a specific heat of 4.18J/(g⋅∘C)for the solution, an initial temperature of 26.0 ∘C, and no heattransfer between the cold pack and the environment.
d)Calculate ΔH∘f (in kilojoules per mole) for benzene,C6H6,(a chemical commonly used by cars) from the followingdata:
2C6H6(l)+15O2(g)→12CO2(g)+6H2O(l)ΔH∘ = -6534kJ
ΔH∘f (CO2) = -393.5kJ/mol
ΔH∘f (H2O) = - 285.8kJ/mol
e) For the reaction, 2 NH3(g) →N2(g) + 3 H2(g), one wouldexpect
1) ΔH° to be negative and ΔS° to be negativeor 2) ΔH° to be positvie and ΔS° to bepositive.
