chm ch 4
Determine the molar mass for fluoxetine (C16H16F3NO), also known as Prozac®.
295.3 g/mol
Which of the following is most biologically damaging type of radiation?
UV-C Remember that UV-C is the most energetic while UV-A is the least energetic.
Increasing wavelength of light goes in this order.
Ultraviolet < visible < infrared
Use the figure below to specify the region of the electromagnetic spectrum where radiation with a wavelength of 600 nm is found.
Visible
radiative forcings are
factors that influence the balance of Earth's incoming and outgoing radiation
Describe the shape of a SO2 molecule.
bent
Which characteristics pertain to the problem of global warming?
- Possible consequences include altered climate and increased sea level. - Heat energy radiated by the earth is captured by atmospheric molecules
Which practices might be described as carbon sequestration?
-planting trees -pumping carbon dioxide deep into the ocean
red↗ %% black↙ %% red↗
-this vibration will change the charge distribution around the molecule -this motion is called a bending vibration -this vibration requires less energy -this vibration directly absorbs infrared radiation
↓red %% black↑ %% red↓
-this vibration will change the charge distribution around the molecule -this motion is called a bending vibration -this vibration requires less energy -this vibration directly absorbs infrared radiation
red→ %% ←black %% red→
-this vibration will change the charge distribution around the molecule -this motion is called a stretching vibration -this vibration requires more energy -this vibration directly absorbs infrared radiation
←red %% black %% red→
-this vibration will not change the charge distribution around the molecule -this motion is called a stretching vibration -this vibration requires more energy -this vibration does not directly absorb infrared radiation
In order to calculate the density of a solution, you divide the mass of a liquid (5.10 g) by its volume (250.0 mL). How should you report its density?
0.0204 g/mL
A certain combustion reaction generates 5.00 moles of carbon dioxide. How many grams does this represent? Report your answer to 3 significant figures.
220g www.convertunits.com/from/moles/to/grams
A certain combustion reaction generates 0.500 moles of carbon dioxide. How many grams does this represent? Report your answer to 3 significant figures.
22g
Calculate the mass of 25,000 molecules of nitrogen gas. (1 mole = 6.02 × 10^23 molecules)
1.16 × 10^−18 g Have to know the chemical formula first - molecules to moles: www.convertunits.com/from/molecule/to/mole second - moles to grams: https://www.convertunits.com/from/moles/to/grams
How many atoms are contained in 3.5 g of carbon? Report your answer in scientific notation, using 2 significant figures.
1.8*10^23 atoms
How many atoms are contained in 3.7 g of carbon? Report your answer in scientific notation, using 2 significant figures.
1.9*10^23 atoms
Calculate the molar mass of CHFCl2. Report your answer to 2 decimal places.
102.92 g/mol www.lenntech.com/calculators/molecular/molecular-weight-calculator.htm
Suppose you have an Avogadro's number of carbon atoms. How many grams does this represent? Report your answer to two decimal places.
12.01g planetcalc.com/6777/
An element has two naturally-occurring isotopes. The mass numbers of these isotopes are 119.00 u and 121.00 u, with natural abundances of 50% and 50%, respectively. Calculate its average atomic mass. Report your answer to 2 decimal places.
120.00 u
his is the Lewis structure for acetic acid. The bond angles are not drawn to scale. Based on the electronic configuration shown in the Lewis structure, predict the O---C---O bond angle, in degrees.
120°
An element has two naturally-occurring isotopes. The mass numbers of these isotopes are 129.00 u and 131.00 u, with natural abundances of 50% and 50%, respectively. Calculate its average atomic mass. Report your answer to 2 decimal places.
130.00 u
Suppose you have an Avogadro's number of nitrogen atoms. How many grams does this represent? Report your answer to two decimal places.
14.01g www.convertunits.com/from/moles/to/grams
A certain combustion reaction generates 3.50 moles of carbon dioxide. How many grams does this represent? Report your answer to 3 significant figures.
154g
If the average temperature of earth is currently 15.0°C, what does the NOAA model (the line in the graph) predict for the average global temperature in 2080?
17.4°C
This figure shows global emissions of C in metric tons per person per year for selected countries. Using this figure, how many metric tons of carbon dioxide are released per person in Australia per year? Report your answer to 1 decimal place.
19.1 metric tons CO2
Place the events of the history of ozone depletion in chronological order.
1930s - Chlorofluorocarbons (CFCs) are invented and used as propellants and refrigerants by people worldwide. 1974 - F. Sherwood Rowland, Mario Molina and Paul Cruzen discover that CFCs are a major cause of stratospheric ozone depletion. 1977 - The United Nations meets and adopts the World Plan of Action on the Ozone Layer. 1978 - The US and Canada ban the use of CFCs in spray cans. 1987 - The Montreal Protocol on Substances That Deplete the Ozone Layer is signed and ratified by countries worldwide. 1990-Present - Production and use of CFCs and other ozone depleting agents dramatically decreases.
What is the mass of one atom of nitrogen? Report your answer to 3 significant figures and use scientific notation.
2.32*10^-23g
What is the mass of exactly 500 sulfur atoms?
2.66x10^-20 g
This figure shows global emissions of C in metric tons per person per year for selected countries. Using this figure, how many metric tons of carbon dioxide are released per person in Canada per year? Report your answer to 1 decimal place.
20.6 metric tons CO2
Suppose you have an Avogadro's number of sodium atoms. How many grams does this represent? Report your answer to two decimal places.
22.99g
Hydrogen gas (H2) is a promising alternative to fossil fuels. How many molecules are present in 1.0 kg of hydrogen gas?
3.0*10^26
One year, a herd of cattle released 5.44 metric tons of CH4 (methane) into the atmosphere. How many metric tons of carbon did this methane contain? Report your answer to 3 significant figures.
4.08 metric tons C total of CH4 x .75 (percent of carbon in CH4) www.lenntech.com/calculators/molecular/molecular-weight-calculator.htm
How much energy is associated with an infrared photon with a wavelength of 4.83 μm? Report your answer in scientific notation using the provided boxes.
4.11x10^-20 www.omnicalculator.com/physics/photon-energy
How much energy is associated with an infrared photon with a wavelength of 4.23 μm? Report your answer in scientific notation using the provided boxes.
4.70×10^-20 J https://www.omnicalculator.com/physics/photon-energy
Calculate the molar mass of N2O. Report your answer to 2 decimal places.
44.01 g/mol
Calculate the molar mass of CO2. Report your answer to 2 decimal places.
44.01g/mol www.lenntech.com/calculators/molecular/molecular-weight-calculator.htm
Calculate the mass% of O in a molecule of sulfur dioxide, SO2. Report your answer to one decimal place.
49.9% OR 50% www.lenntech.com/calculators/molecular/molecular-weight-calculator.htm
One year, a herd of cattle released 7.64 metric tons of CH4 (methane) into the atmosphere. How many metric tons of carbon did this methane contain? Report your answer to 3 significant figures.
5.73 metric tons C total of CH4 x .75 (percent of carbon in CH4) www.lenntech.com/calculators/molecular/molecular-weight-calculator.htm
Give the number of outer (valence) electrons for an atom of oxygen.
6 outer electron(s)
UV-B radiation has a frequency of approximately 1017 s−1. What is the energy of a photon of this light?
6.63 × 10−17 J www.omnicalculator.com/physics/photon-energy s^−1 = Hertz
Calculate the energy of a photon of electromagnetic radiation with a wavelength of 298.7 nm. Report your answer in scientific notation using the provided boxes.
6.65x10^-19 J www.omnicalculator.com/physics/photon-energy
A certain combustion reaction generates 2.00 moles of carbon dioxide. How many grams does this represent? Report your answer to 3 significant figures.
88.0g planetcalc.com/6777/
Atmospheric concentration, lifetime, and even efficiency of absorption in the IR are all factors that make a gas into a concerning greenhouse gas. Match the terms below with true examples. Hint: each term may have one or more examples.
Atmospheric concentration: -carbon dioxide concentrations are nearing 400 ppm. Atmospheric lifetime: -Carbon dioxide can be removed from the atmosphere by dissolution into the oceans. -methane readily reacts with tropospheric free radicals Infrared absorption efficiency: -The polarity of CFCs and the tetrahedral shape means that they absorb infrared at multiple wavelengths. -The bent shape and partial changes of nitrous oxide will lead to a large number of molecular vibrations that absorb IR.
Scientists have correlated average global temperature with atmospheric carbon dioxide levels for the last 160,000 years using ice cores from Antarctica. How is the carbon dioxide level determined?
By measuring the CO2 concentration in trapped air bubbles in the ice layers
Which statement is correct? A. UV-A is the most energetic of the three forms of UV light. B. UV-B is the most energetic of the three forms of UV light. C. UV-C is the most energetic of the three forms of UV light. D. UV-A, UV-B, and UV-C are equally energetic.
C. UV-C is the most energetic of the three forms of UV light.
Although carbon dioxide is the primary compound discussed with respect to global warming; of the common atmospheric components the global warming potential (GWP) of a carbon dioxide molecule is very low. Which statement best explains this pair of facts?
CO2 exists in relatively high concentrations
Give the number of carbon atoms, hydrogen atoms, and fluorine atoms in a molecule of HFC-32.
Carbon atoms: 1 Hydrogen atoms: 2 Fluorine atoms: 2 www.lenntech.com/calculators/molecular/molecular-weight-calculator.htm (first row)
What is the role of polar stratospheric clouds (PSCs) on the destruction of ozone?
Chemical reactions occur on the clouds that convert molecules that do no damage to those that deplete ozone Remember that PSCs only form in the Antarctic and that is where the ozone hole exists.
Which explanation accounts for the fact that, on average, cloudy nights are warmer than clear nights?
Clouds are composed of water vapor and H2O is a strong greenhouse gas Think about what clouds are made of and how that interacts with IR radiation.
Decreased stratospheric ozone concentrations may lead to A. increased incidences of melanomas. B. harm to young marine life. C. an increased occurrence of cataracts. D. All of these choices are correct
D. All of these choices are correct
In order to halt increases in the amounts of these gases in the Earth's atmosphere, global greenhouse gas emissions must be decreased by 9 billion tons. Which of these would not provide that much relief in global greenhouse gas emissions? A. Cutting energy usage in the world's buildings by 20-25 percent below business-as-usual B. Having all cars get 60 mpg instead of 30 mpg C. Replacing 700 large coal-burning power plants with nuclear, wind, or solar power D. Capturing and sequestering carbon dioxide at 800 coal-burning power plants E. None of these choices would provide the needed 9 billion tons
E. None of these choices would provide the needed 9 billion tons
Which process plays the most important role in the greenhouse effect?
Energy radiated by the earth is absorbed by the atmosphere Remember that infrared radiation is emitted from the earth and back into the atmosphere.
Which of the following photons from the electromagnetic spectrum have the most energy?
Gamma Ray
Which of these represent the best Lewis structure for acetylene (C2H2)
H-C≡C-H
Categorize each compound as an HFC, CFC, HCFC or Halon.
HFC - C2HF5, CH2F2 HCFC - CHClF2, C2H3Cl2F CFC - CCl3F, CCl2F2 Halon - CBrF3
Why are HFCs environmentally superior to the currently used HCFCs?
HFCs do not contain chlorine
Which conclusion was considered "very likely" in the 2014 report of the Intergovernmental Panel on Climate Change?
Human-caused emissions are the main factor causing warming since 1951
Which of the following is NOT a likely consequence of increased carbon dioxide concentration in the atmosphere?
Increase in biodiversity
What international agreement attempted to reduce greenhouse gas emissions?
Kyoto Protocol
Describe the shape of a CO2 molecule.
Linear
Which atmospheric component does not contribute to global warming?
N2
Which of the following has the lowest albedo?
Ocean
Give the number of protons, neutrons, and electrons in a neutral atom represented by 111/48Cd
Protons: 48 Neutrons: 63 Electrons: 48 www.omnicalculator.com/chemistry/atom
Which of the following photons from the electromagnetic spectrum have the least energy?
Radio Waves
Place types of electromagnetic radiation listed below in order from shortest wavelength to longest wavelength.
SHORTEST Gamma Rays X-Rays UV-Visible Infrared (IR) Microwave Radio Waves LONGEST
Label the diagram below with the different types of electromagnetic radiation in the EM spectrum.
Shortest to longest 10^-12: Gamma Rays 10^-9: X-Rays 10^-8: Ultraviolet (UV) 10^-7: Infrared (IR) 10^-5: Visible 10^-2: Microwave >10^-1: Radio Waves
In Earth's atmosphere, where is the ozone layer?
Stratosphere
The ability of a molecule to absorb infrared radiation is measured with IR spectrometers, which report the frequency of light absorbed in units of cm¯1. Which explanation best describes this unit?
The number of wavelengths in 1 cm for a specific frequency of light
How do mineral nanoparticles in sunscreens protect from UV radiation?
The particles absorb incoming UV light
Choose from the conversion factors given to complete the following diagram of amount-mass-number-volume relationships for a solution.
Top row (1 blank) - molar mass (g/mol) of substance bottom row (2 blanks) - avogadro's number (entities/mol),, Molarity (mol/L) of solution
Determine the shape or geometry of PH3. (Hint: Use the Periodic Table to arrive at the electron configuration for phosphorous.)
Trigonal pyramidal
Determine the shape or geometry of PH3. (Hint: Use the Periodic Table to arrive at the electron configuration for phosphorous.)
Trigonal pyramidal Remember that the central atom has three atoms and no lone pairs around it.
The warming of a car in the sun is an excellent analogy for the greenhouse effect of our atmosphere. Complete the analogy with the words and phrases then place the sentences in order.
When sunlight hits a car, its windows absorb some radiation, such as UV-(B). In the atmosphere, (ALL) of the UV-(C) and (SOME) of the UV-(B) radiation is absorbed by reactions of oxygen and ozone in the (STRATOSPHERE). The car windows allow (VISIBLE LIGHT) and infrared radiation to pass into the car. Similarly, our atmosphere allows (HIGHER ENERGY) infrared radiation and (VISIBLE LIGHT) to pass through. The car's interior, like the Earth's (ROCKS AND SOIL), absorbs (VISIBLE LIGHT) and (HIGHER ENERGY) infrared radiation then emits (LOWER ENERGY) infrared radiation back out. The car windows, like the (GREENHOUSE GASES) of our atmosphere, trap the (LOWER ENERGY) infrared radiation and makes the interior warmer than the outside.
When it reaches its largest size, the ozone hole over the Antarctic is
about as large as North America.
Ozone in our atmosphere is important because it
absorbs some UV radiation
Radiative forcings are factors that influence the balance of the Earth's incoming and outgoing radiation. Order these selected examples from Cooling to Warming.
aerosols - stratospheric ozone - methane - carbon dioxide
The majority of N2O molecules in the atmosphere come from
bacterial removal of nitrate ions (NO3−) from soil. Remember that this is part of the nitrogen cycle.
The structure of ozone most closely resembles a
bent molecule with the same length of chemical bonds, for example, Remember the effects of lone pairs that repel each other and force the molecule into a bent shape.
Which contributes to the ozone hole?
chlorofluorocarbons (CFCs) only CFCs contain chlorine, which acts as catalyst for ozone destruction. The others are environmental concerns, but don't contribute to ozone hole
Molecules and electromagnetic radiation interact. Atoms may dissociate, a molecule may rotate, or bonds may stretch and bend. Carbon dioxide has four possible vibrations. Select the true statements about the vibrations below.
cont. below
In order to make useful predictions, which factors must be accounted for by climatic models? i. Cooling effect of atmospheric aerosols ii. Smoke, haze, and cloud cover iii. Change in land use iv. Combustion of fossil fuels
i, ii, iii, and iv
Methane is approximately 23 times more powerful than carbon dioxide as a greenhouse gas. Which are significant sources of methane emissions? i. The digestive systems of ruminants (cows, sheep, etc.) ii. Automobile exhaust iii. Rice cultivation iv. Decaying wetland vegetation
i, iii, and iv only
Which occurrences or processes are expected to reduce the level of atmospheric carbon? i. Decaying plant and animal remains ii. The growth of trees iii. Formation of carbonate rock in the ocean iv. Animal respiration
ii and iii only
The "ozone layer" is found
in the stratosphere. Good ozone is found high in the atmosphere.
speed of light in air
is independent of the wavelength and frequency of light
Vibrations of some molecules will absorb infrared radiation while others will not. Do the following vibrations absorb? Select Yes or No.
nitrogen - No dicholorodifluoromethane - yes carbon dioxide - no
In reference to waves, frequency is the
number of waves passing a fixed point in one second
Vibrations of some molecules will absorb infrared radiation while others will not. Do the following vibrations absorb? Select Yes or No.
oxygen - no carbon dioxide - yes dichlorodifluoromethane - yes
Which corresponds to the composition of the ion typically formed by fluorine?
protons: 9 electrons: 10 net charge: 1-
Many different processes contribute to maintaining the Earth's energy balance. Sort each example into the most appropriate place in the energy balance.
reflected from atmosphere - dust particles are suspended in atmosphere reflected from surface - polar ice caps are visible from space emitted from surface - asphalt and rocks feel warm to the touch absorbed in atmosphere - methane gas interacts with energy in the atmosphere absorbed by earth - plants conduct photosynthesis absorbed in atmosphere - oxygen gas is split into oxygen atoms after absorbing photons of light
Radiative forcings are factors that influence the balance of the Earth's incoming and outgoing radiation. Order these selected examples from Cooling to Warming.
smoke, soot, and sulfate aerosols from coal combustion - fresh snow in winter - increased sunspots - halocarbons (CFCs and HCFCs) in the atmosphere
Predict the molecular shape for each of these compounds. Remember to consider all of the outer electrons before you make your choice.
tetrahedral - dichlorodifluoromethane,, methane trigonal pyramid - ammonia trigonal planar - sulfur trioxide bent - sulfur dioxide, nitrogen dioxide, water, ozone linear - nitrogen, carbon dioxide
The O-to-O-to-O bond angle in an ozone (O3) molecule is not exactly 120° because
the nonbonding electron pair occupies greater space than the bonding pairs.
Choose from the conversion factors given to complete the following diagram of amount-mass-number relationships for two species, A and B, in a chemical reaction.
top row (3 blanks) - Molar mass (g/mol) of substance A,, Molar ratio from balanced equation,, molar mass (g/mol) of substance B bottom row (2 blanks) - avogadro's number (entities/mol),, avogadro's number (entities/mol)
Choose from the conversion factors given to complete the following diagram of amount-mass-number relationships for a compound.
top row (3 blanks)- molar mass (g/mol) of substance,, chemical formula of substance,, atomic mass (g/mol) of element bottom row (2 blanks)- avogadro's number (entities/mole),,avogadro's number (entities/mole)
The Montreal protocol is a
treaty to reduce the amount of CFCs produced in the world.
DNA, the genetic material of living organisms, is damaged by light in the
ultraviolet region, especially below a wavelength of 320 nm. Damage by EM radiation usually occurs to structure that are of the same size as the wavelength of the radiation.
Although greenhouse gases likely account for the problem of global warming, they are also responsible for making earth habitable. What would be the temperature on earth in the absence of the effects of carbon dioxide and water?
−18°C Remember that the average temperature of the earth is about 15°C at present and that we are not too far from or too close to the sun.
