Final Exam for Chem 105
A piece of charcoal has a carbon-14 radioactivity that is 1/2 the amount that would be present in freshly burned charcoal. Given that the half-life of carbon-14 is 5730 years, how old is the charcoal?
1 x 5730 = 5730 years
Which set of coefficients should be used to balance the following equation?
1, 6, 4, 4
Which of the following quantities represent the smallest mass?
10 mg
The pH of a sample of water from a river is 6.0. A sample of effluent from a food processing plant has a pH of 4.0. The concentration of hydronium ion in the effluent is?
100 times (100x) larger than the river hydronium ion concentration
After a plant dies, how many years will it be when 25% of the original carbon-14 remains given that the half-life of C-14 is 5730 years?
11460 years
During the combustion of coal (usually represented as carbon in chemical reactions), the main reaction is C + O2 --> CO2. Therefore, how many grams of carbon are needed to produce 44 g of carbon dioxide assuming exactly 32 g oxygen from the atmosphere is consumed?
12 g
Which of the following does NOT contain Avogadro's number of particles?
12 g of water
What is the Cation Exchange Capacity (CEC) for soil with : 3 cmol/kg H+, 3 cmol/kg Na+, 3 cmol/kg K+, 2 cmol/kg Mg2+ , 1 cmol/kg Ca2+
15 cmol/kg
How many protons are there in a sulfur atom?
16
Aspirin has a formula C9H8O4. The molar mass of aspirin is?
180 g/mole
How many electrons can fit in the FIRST electron shell (also called an orbital)?
2
The following reaction is important in the removal of sulfur dioxide, a major source of acid rain, from the smokestacks of coal burning power plants. When the equation below is balanced, the coefficient of calcium oxide is? CaO + SO2 + O2 --> CaSO4
2
When the equation is balanced, the coefficient of sodium fluoride is? NaF + H2SO4 --> Na2SO4 + HF
2
Approximately what percent of the electricity in the USA is created using nuclear power plants?
20%
How many micrograms are in 20 mg?
20,000 ug
Scadium's atomic number is 21 and its atomic mass is 45. It must have ___ protons, ____ neutrons, and ____ electrons?
21, 24, 21
What is Q when Thorium-234 undergoes beta decay?
234/91 Pa
The molar mass of CO is?
28 g/mole
Which one of the following reactions is NOT balanced?
2KNO3 + 10K --> 5K2O + N2
When oxygen, O2, is passed through an electrical spark (lightning is a good natural source of an electrical spark), ozone, O3, is formed. When the equation is balanced, the coefficient of oxygen and ozone are? O2 --> O3
3 and 2
What is the voltage of a Barium-Fluoride battery given the following Standard Reduction Potentials? -2.90 V 2.87 V
5.77 V
How many grams of NaCl must be added to 1.0 L solution to create 1.0 molar NaCl?
58.45 g
Avogadro's number is?
6.022 x 10^23
A small but significant amount of the sugar in beets is glucose. Dr. Rachel Lloyd quantified the glucose in Nebraska grown sugar beets using Fehling's test. That test involves adding an excess of blue colored copper (II) ion solution, waiting for a solid brick red colored precipitate of copper (I) oxide to form, collecting and weighing the precipitate, and then using the copper (I) oxide mass to calculate how many moles of glucose were in the original solution. Let's flip that around. If there was 0.05 moles of glucose in the beet solution, how many grams of brick-red precipitate would be formed given that the molar mass of copper (I) oxide is 143 g/mol? Glucose (C6H12O6) + 2H2O + 2Cu^2+ (aq) --> Gluconic acid (C6H12O7) + Cu2O (s) + 4H^+
7.15 g
When the following equation is correctly balanced, what is the coefficient for O2? C5H12 + O2 --> CO2 + H2O
8
How many moles of sulfur atoms are present in 4.00 moles of SiS2?
8.00
What is the mass of 0.500 mol of H2O?
9.01 g
Which of the following isotopes contains 4 neutrons?
9/5 B
The Lewis Dot Structure for atmospheric nitrogen is?
:N:::N:
In a molecule of bromine, Br2, the bromine atoms are bonded to each other by?
A single covalent bond
According to the documentary 'An Convenient Truth," what is the evidence that global warming is occurring?
All of these
Which type of radioactivity has a positive charge?
Alpha, a
Relative to the mass of the nucleus of an atom, the mass of the electron is?
Always much smaller
Acid rain is caused by acidic pollutants in the air. Which of the following pollutants does NOT contribute to acid rain?
Ammonia, NH3
What is matter?
Anything with mass and volume
Which one of the following is NOT part of Dalton's atomic theory?
Atoms change into other atoms in chemical reactions
The temperature at which solid melts is the melting point go the solid. The melting point is an indication of the intermolecular forces that hold a solid together. Lead melts at 328 C. aluminum melts at 660 C. Gold melts at 1064 C. Which one of the following ranks the intermolecular forces in these solid elements from the strongest to the weakest?
Au > Al > Pb
The compound CH3NH2 reacts with water to form CH3NH3+ and OH-. In this reaction, CH3NH2 is acting as a(n)?
Base
A stream of electrons in an electric field would?
Be attracted to the positive electrode
Which equation represents the process of methanogenesis?
CO2 + 4 H2 ---> CH4 + 2 H2O
Lime is used in farming to reduce the acidity of the soil. The chemical name for lime is calcium oxide. When water in the soil reacts with lime, what base is formed?
Ca(OH)2
The formula of calcium chloride is
CaCl2
Consider the following equation: Ca + 2HCl --> CaCl2 + H2 Identify the products for this reaction?
CaCl2 and H2
Electrolytes are important substances in the chemistry of living systems. An electrolyte?
Conducts electricity when melted or out into solution
The process of beta emission can be envisioned as the?
Conversion of a neutron to a proton and electron. The electron is emitted
Which statement is true about covalent compounds?
Covalent compounds have atoms bonded together by shared electrons
Identify the species being oxidized in the following reaction: Cr+ + Sn4+ --> Cr3+ + Sn2+
Cr+
When alchemists of the 1700s needed something that was extremely poisonous, they made Aqua Tofani. In the 1800s, the early chemists determined that Aqua Tofani was composed of arsenic 3+ ion and oxide ion. What is the modern chemical name and composition for Aqua Tofani
Diarsenic trioxide; As2O3
Ethane has the formula CH3CH3. What is the predominant intermolecular force between ethane molecules?
Dispersion forces
The name of the compound S2O3 is?
Disulfur trioxide
The number of protons is always equal to the number of ____ is an uncharged atom?
Electrons
A pure substance that cannot be broken down into simpler substances by chemical pr physical means would be a(n)?
Element
When strontium (Sr) reacts with iodine (I), strontium ions and iodide ions are formed. In this reaction, iodine atoms?
Gain electrons
Silver is plated on copper by immersing a piece of copper into a solution containing silver ions. In the plating reaction, silver ions?
Gain one electron and are reduced
A sample of rainwater has a pH of 3.5. What ion is sure to be present in relatively large concentration in this rain sample?
H3O+
A metalloid?
Has properties intermediate between metals and nonmetals
A shrewd but tentative, initial explanation for a relatively small set of observations is best described as a?
Hypothesis
Radiation with enough energy to knock electrons off atoms or molecules is known as?
Ionizing radiation
Which is NOT one of the three types of radiation emitted from radioactive elements?
Lambda, A
The specific pattern of colors emitted by excited atoms is called a?
Line spectrum
In reactions to form ionic compounds, metals generally?
Lose electrons
In the famous relationship E = mc^2, the symbol m represents?
Mass
In the post-apocalyptic movie "Max Max Beyond Thunderdome," what was the energy source used to run "the lights, the motors, the vehicles" in Bartertown?
Methane combustion
Which of the following is able to raise the pH value of water?
NaOH
Which of the following is NOT a redox reaction?
NaOH + HCl --> NaCl + H20
The quantity 10^-9 (one billionth) is designated by the prefix?
Nano
Most atoms and molecules call into which size range?
Nanometers to micrometers
The element with the ground state electron configuration of 1s2 2s2 2p6 is?
Ne
In the fission of uranium-235, which particle causes and propagates the chain reaction?
Neutron
A one molar solution is a solution that contains one mole of solute in?
One liter of solution
In the water molecule, H2O, the oxygen end of the molecule is more negative than the hydrogen end because?
Oxygen is more electronegative than hydrogen
Which bond has the most covalent character?
P-Cl
When an electron in an excited atom falls from a higher to a lower energy level, the excited atom emits a characteristic?
Photon
Water dissolves so many things because it is one of the most ____ liquids known.
Polar
An element is determined by the number of?
Protons
Which is a correct description of the organization of subatomic particles in atoms?
Protons and neutrons are tightly packed into a small nucleus. Electrons occupy the space outside the nucleus
The shape of the ammonia molecule is?
Pyramidal
A pH buffer?
Resists change in pH when small amounts of a strong acid or strong base are added
How many dots will appear in the Lewis dot structure for an element from Group 17 of the periodic table?
Seven
How many electrons are there in a triple bond?
Six
Which of the following is not an important predictor for nitrate concentration in groundwater?
Soil pH
Which state of matter is characterized by having molecules close together and vibrating in place?
Solid
The degree of order of matter is directly proportional to the cohesive forces that hold the matter together. In other words, the more organized the state of matter, the stronger the "glue" that holds it together. Which of the following ranks these cohesive forces from the state with the strongest to that with the weakest cohesive force?
Solid > Liquid > Gas
Iconic compounds have strong forces between particles. This means that generally ionic compounds are ___ at room temperature.
Solids
The line spectra of atoms provides experimental evidence for?
The arrangement of electrons
The kinetic-molecular theory of gases assumes which of the following?
The average kinetic energy of gas molecules will increase when you lower the temperature of the gas
Water is a liquid at room temperature while methane is a gas. Which statement compares the intermolecular forces in these molecules correctly?
The intermolecular forces in water are stronger than those in methane
After the Electric Pickle demonstration, first we shared our observations and then we hypothesized how those observations occurred. Which of the following hypotheses would be tested most directly by first making pickles that are soaked in different salt solutions, such as LiCl, NaCl, KCl, and RbCl?
The pickle emits orange light
Which of the following statements is NOT an issue when constructing and operating nuclear power plants?
The possibility of a "nuclear bomb-like" explosion
The equation, 2NaOH + H2SO4 --> Na2SO4 + 2H2O, does NOT tell us that?
The reaction will occur rapidly
It is possible to create a voltaic pile with pennies, nickels, and pieces of salty paper by stacking them into a pile. The voltmeter will show that the pile is producing electricity. What is the role of the salty paper in causing the pile of coins to be a battery?
The salt stimulates corrosion of the copper ions on the surface of the pennies, and then the copper ions readily accept electrons from the adjacent nickels
Radioactivity is?
The spontaneous emission of radiation from unstable elements
In a Lewis formula, the dots represent?
The valence electrons in all the atoms
Which of the following is NOT TRUE about rare earth elements?
They are the least abundant elements on Earth
When we say that noble gases are inert, we mean they?
Undergo very few chemical reactions
Which of the following radioactive isotopes can be used to create an atomic bomb or run a nuclear power plant?
Uranium-235
With respect to chemical bonding, which particles play the most active role?
Valence electrons
A barium ion, Ba2+, has the same electron configuration as a(n):
Xenon atom
In the zinc-copper electrochemical cell shown to the right which statement most completely describes the reasons that the electrons flow through the external wire in the direction shown? Zn ... e- ---> ..... Cu
Zinc metal, Zn, is oxidized to produce zinc ions that dissolve in the solution and two electrons that travel to the copper metal. Once at the cooper metal, Cu, the electrons reduce copper ions in the solution for form copper atoms that are deposited on the copper metal
Reduction means _____, Oxidation means _________
gaining electrons; losing electrons
