Chem 1 midterm
the numbers of 1-4 are used to identify four dif elements on periodic table. Which element is expected to have 2+ charge when it forms an ion
1(look at photo 30)
the hydronium ion concentration in a solution with a pH 10 is ___than the hydronium ion concentration in a solution with a pH 13
1,000 times greater
choose the proper coefficients for each substance to balance this equation
1,3,2,2
the majority of new smartphones being relseased have displays that are at least 5 inches in size. What is this size in centimeters? (there are 2.54 cm in one inch)
12.7 cm ( 2.54 X 5)
This 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 degrees
A 4-L sample of water contains 80 of lead. What is the lead concentration in parts per billion
20
CO2 emissions in China declined by 9 percent over the five-year period ending in 2000. If 5.00 × 108 metric tons (t) of CO2 was emitted in 1995, how much CO2 was released in 2000?
4.55 x 10^8t
a calorie is defined as exaclty 4.184 J. Therefore 1.000 cal is exaclty
4184J
The heat of combustion of ethane, C2H6, is 1560 kJ/mol. What is the heat of combustion of ethane, in kJ per gram?
51.9 kJ
the greenhouse and enhances greenhouse effects refer to the return of approx___percent and greater than _____
80:80
free radicals are
All of these correctly describe free radicals
what is the name of the hydrocrabon C4H10
Butane
what is the chemical formula for carbon disulfide
Cs2
which covalent bond is the most polar
H---O
which chemical equation shows the dissociation of two protons from trihydrogen phosphate
H3PO4--2H+ + HPO4^2-
which substance is not considered to be an air pollutant
N2
which of the following is a weak base
NH3
which component of the air is an element
O2
when dissolved in water, hydrogen bromide (HBr) forms hydrobromic acid. Determine the hydroxide ion concentration in a 4,500 mL solution containing 3.78 hydrogen bromide K=1.00 x 10^-14
OH=9.63 x 10^-13
Which region of the ultraviolet spectrum is absorbed least by the atmosphere?
UV-A
which differentiates a compound from a mixture of two or more elements?
a compound does not exhibit the individual properties of the elements of which it is composed
what is a biological oxygen demand (BOD)
a measure of the amount of dissolved oxygen microorganisms use up as they decompose organic wastes found in water
when it reaches its largest size, the ozone hole over the antarctic is
about as large as North America
which is not a pure substance?
air
which is correct
all of these are correct
In order to make useful predictions, which factors must be accounted for by climatic models?
all options
Which factor did not play a major role in the formation of fossil fuels from plant matter?
an abundance of sunlight
both the clinton and G.W. Bush administration were unwilling to sign the Kyoto Protocol. What was the primary objection to the treaty
developing countries are not required to control greenhouse gas emissions
when an atom absorbs visible radiation
electrons jump from lower energy level to higher energy levels
How is heat energy used to generate electricity in a modern power plant?
heat boils water to make steam which drives a turbine
any chemical or physical change that absorbs energy
is an endothermic process
The energy of motion is called ________ energy.
kinetic
question 41
look at photo
which corresponds to the composition of the ion typically formed by magnesium
look at photo 29
which corresponds to the composition of the ion typically formed by fluorine
look at photo of #28
which shows the balanced equation for the reaction of nitrogen
look at question 9
air is a
mixture
A(n) _______ is a fixed number if atoms held together by chemical bonds in a certain spatial arrangement
molecule
what distinguished the atoms of one element from another
number of protons
arrange these types of radiation in order of increasing energy per photon
radio waves-infrared radiation-visible light-UV-gamma rays
Which pollutant is present in air as particulate matter?
soot
which of the following is a chemical change?
souring milk
The O2 molecule breaks apart at lower wavelengths than the O3 molecule. What is the main reason for this
the average bond in O2 is shorter and stronger than that of O3
cracking is
the breaking of larger molecules into smaller ones
green chemistry is
the design of products and processes that reduce hazardous substances
which occurrences or processes are expected to reduce the level of atmospheric carbon
the growth of trees, formation of carbonate rock in the ocean
A .25 M aqueous solution of potassium chloride, KCl, is tested for conductivity using the type of apparatus shown. What do you predict will happen
the light bulb will shine brightly -KCl is highly ionized in aqueous solution
Why are HFCs inappropriate for long-term replacement of CFCs?
they absorb infrared radiation
the lowest (or closest to the ground) layer of the atmosphere is
troposphere
ozone is considered pollutant in the _____but is valuable layer in the
troposphere, stratosphere
increasing wavelength of light goes in this order
ultraviolet, visible, infrared
which is not a consequence of hydrogen bonding between water molecules
water is colorless and odorless