Exam 2

Infrared light interacts with matter to cause
increased vibration
The band of the electromagnetic spectrum central to the greenhouse effect is…
infrared light
The greenhouse effect is caused by gases that
absorb infrared radiation
The atmosphere is almost transparent to which band of electromagnetic spectrum
visible
Which substance is not a greenhouse gas?
nitrogen
Predict the geometry at the carbon atoms in acetylene (c2h2)
linear
Predict the geometry at the carbon in formimine (CH3N)
trigonal planar
Predict the geometry at the nitrogen in formimine (CH3N)
bent
Chemists use a very large number to designate a “standard” pile of atoms or molecules. This number is called….
Avogrados number
Find the molar mass of ethanol, C2H6O
46.07 g/mol
What is the coefficent for oxygen in the balanced chemical equation for the combustion of heptane? (C7H16)
11
How many moles of water molecules are contained in 144g of water?
8.0 moles
How many mole of hydrogen atoms are contained in 144g of water
16.0 moles
How much oxygen is contained in 100g of water?
88.9 g
Scientists believe deforestation leads to global warming because…
trees are net consumers of carbon dioxide
Infared light has a shorter wavelength than…
microwaves
Which of the following properties of hydrogen does not describe one of its advantages as a fuel?
a low energy to volume ratio
A truly inexhaustible supply of energy will be available to us when we…
learn how to convert light energy into chemical energy efficiently
A battery converts chemical energy into….
electrical energy
Which substance is likely to have the highest boiling point?
C18H38
The electron transfer process in batteries can convert chemical energy to electrical energy with efficiencies approaching..
90%
In lecture we discussed the use of ethanol as a fuel. How much energy is “lost” in the transformation from sugar to ethanol
60 kJ/mole sugar
Consider the reaction shown below: CH4+ 2O2 -> CO2 + 2H2O Which of the following statements might be made most readily about this reaction.
Its exothermic (releases energy)
Which one of the following groups of fuel sources include only fossil fuels?
oil, natural gas, hydropower
The components of crude oil are separated on the basis of what physical property
Boiling point
The process of electron transfer involves…
the movement of electrons from a locus of high potential energy to a locus of low potential energy.
e conversion of heat energy into mechanical energy is inherently inefficient because…
of the random nature of heat energy.
A compelling argument for the use of renewable plant derived fuels such as ethanol and biodiesel would likely include what fact
The carbon contained in them is taken from the atmosphere.
From an environmental perspective, the use of fossil fuels as an energy source is undesirable because..
they all release long sequestered carbon into the atmosphere as carbon dioxide.
At present, the recoverable supply of coal is approximately…
20-40 times greater than oil reserves.
From what element are PV (photovoltaic) cells predominantly made?
silicon
Which description best describes the process of recharging a battery?
the conversion of electrical energy into chemical energy
Which element is used as an n type dopant in PV silicon crystals?
antimony (Sb)
P- Type (in PV [ photovoltaic cells ])
1 less electron relative to silicon
N-type in PV [ photovoltaic cells ])
1 more electron relative to silicon