Combustion reactions involving hydrocarbons produce heat (are exothermic, ∆H < 0 ) and form
many moles of gaseous products (greater entropy, ∆S > 0), and are therefore spontaneous (∆G
< 0 ) at all temperatures. The reaction doesn’t go at room temperature on its own because the
activation energy is high; it needs an external heat source to get it going.111 . F, F
In fact, the spontaneous reaction is the very opposite of what is described. Zinc will displace
copper ions from solution, giving copper metal and a solution of zinc ions. The definition of a
“more active” metal is that it will displace ions of a less active metal from solution; the less
active metal is reduced and the more active metal is oxidized.
112 . F, T
The glowing ember on the splint would be extinguished completely (cease to glow).
Combustion requires oxygen gas and produces CO 2 . A sample of purified CO 2 cannot support
continued combustion.
113 . T, F
The SO 2 molecule has a Lewis dot structure of
The electron pair geometry for this structure is trigonal planar, not linear. The sulfur in SO 2 is
sp^2 hybridized.114 . F, T
The isotope number is the sum of the neutrons and protons. Therefore, the neutrons are
37−17 = 20. The isotope chlorine-37 has 17 protons, 20 neutrons, and 17 electrons. The atomic
mass of chlorine is 35.43 amu.
115 . T, T, CE
According to Graham’s law of effusion, at isothermal and isobaric conditions, the rates of
effusion for two gases are inversely proportional to the square root of their molar masses.
Therefore, because helium has a lower molar mass than neon, it will effuse faster than neon.
116 . T, T, CE
At room temperature chlorine is a gas and bromine is a liquid, so bromine has a higher boiling
point than chlorine. Bromine has a higher boiling point because it has stronger intermolecular