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100
A certain element consists of two stable isotopes.
The first has a mass of 121 amu and a percent natural abundance of 57.3 %.
The second has a mass of 123 amu and a percent natural abundance of 42.8 %.
What is the atomic weight of the element?
122 amu
Atomic weight = (fraction 1 
mass 1) + (fraction 2 mass 2)
Atomic weight = (0.573121 amu) + (0.428123 amu) = 122 amu
100
In the laboratory, a student finds that it takes 192 Joules to increase the temperature of 13.3 grams of solid magnesium from 24.8 to 39.9 degrees Celsius.
The specific heat of magnesium calculated from her data is------ J/g°C
0.956
100
Draw a Lewis Structure for NO2F
Determine the number of resonance structure
Determine the average bond order
2
average bond order is 1.5
bond order: number of bonds/resonance
100
Summarize Boyle's, Charles's and Avogadro's Law?
Boyle's Law states that the pressure and the volume of a gas sample are inversely proportional when the temperature and the amount of gas are constant. Mathematically this becomes: P1V1 = P2V2, where P and V may be in any self consistent units.
Charles's Law states that the volume of a gas sample is directly proportional to its absolute temperature when the pressure is held constant. In mathematical terms this becomes
V1/T1 = V2/T2
Avogadro's Law states that equal volumes of gases at the same temperature and pressure contain the same number of molecules.
100
Using only the periodic table arrange the following elements in order of increasing atomic radius:
sulfur, sodium, silicon, aluminum
smallest to largest:
sulfur, silicon, aluminum, sodium
200
8. How many grams of NaH2PO4 are needed to completely neutralize 33.65 mL of a 0.129 M NaOH solution?
NaH2PO4+NaOH---> Na3PO4+H2O
1NaH2PO4+2NaOH--->1 Na3PO4+2H2O
0.260grams
200
In the laboratory a "coffee cup" calorimeter, or constant pressure calorimeter, is frequently used to determine the specific heat of a solid, or to measure the energy of a solution phase reaction.
A student heats 61.53 grams of tin to 97.87 °C and then drops it into a cup containing 79.39 grams of water at 21.69 °C. She measures the final temperature to be 24.66 °C.
The heat capacity of the calorimeter (sometimes referred to as the calorimeter constant) was determined in a separate experiment to be 1.83 J/°C.
Assuming that no heat is lost to the surroundings calculate the specific heat of tin.
0.220 J/g°C.
200
Draw the Lewis Structure for AlF3
Determine its molecular geometry
Draw the lewis structure for BrO4-
Determine its molecular geometry
trigonal planar
tetrahedral
200
A sample of xenon gas at a pressure of 0.927 atm and a temperature of 22.4 °C, occupies a volume of 676 mL. If the gas is compressed at constant temperature until its pressure is 1.27 atm, the volume of the gas sample will be ……. mL
493 mL
Boyle's Law
200
Write the complete electron configuration for the chlorine atom.
Using NOBLE GAS notation write the electron configuration for the lithium atom.
1s2 2s2 2p6 3s2 3p5.
[He]2s1.
300
When 3.904 grams of a hydrocarbon, CxHy, were burned in a combustion analysis apparatus, 12.25 grams of CO2 and 5.015 grams of H2O were produced.
In a separate experiment, the molar mass of the compound was found to be 56.11 g/mol. Determine the empirical formula and the molecular formula of the hydrocarbon.
Empirical Formula: CH2
Molecular Formula: C4H8
300
A local FM radio station broadcasts at a frequency of 98.5 MHz.
Calculate the wavelength at which it is broadcasting in meters
(1 MHz = 10^6 s -1)
3.04 meters
300
Draw the Lewis structure for SeO3 2-
Draw all the possible resonance structures?
Determine which is the best by using the concept of electronegativity and formal charge
lone pair on Se and one of the Oxygens has two bonds
300
A sample of argon gas at a pressure of 683 mm Hg and a temperature of 85 °C, occupies a volume of 5.56 liters. If the gas is heated at constant pressure to a temperature of 110 °C, the volume of the gas sample will be… L
5.95 L
Charles's Law
300
It is desired to inflate a baggie with a volume of 836 milliliters by filling it with neon gas at a pressure of 1.48 atm and a temperature of 285 K. How many grams of Ne gas are needed?
1.07 g
ideal gas law
400
2Fe3+ + Co
2Fe2+ + Co2+
Determine species oxidized, species reduced, oxidizing agent, reducing agent, and where electrons flow from?
Species oxidized: Co
Species reduced: Fe3+
Oxidizing agent: Fe3+
Reducing agent:Co
Electrons flow from Co to Fe3+
400
A local AM radio station broadcasts at a frequency of 856 KHz.
Calculate the energy of the frequency at which it is broadcasting in kJ/ photon?
1 KHz = 10^3 sec -1)
5.67x10^-31 KJ/photon
400
A. What is the hybridization of the central atom in IBr3? Determine polarity
B. What is the hybridization of the central atom in BrF5? Determine polarity
sp3d; polar
sp3d2; polar
400
An aqueous solution is made by dissolving 22.9 grams of ammonium sulfate in 491 grams of water.
The molality of ammonium sulfate in the solution is ------ m.
0.353
moles of solute/kg of solvent
400
You need to make an aqueous solution of 0.214 M aluminum chloride for an experiment in lab, using a 300 mL volumetric flask. How much solid aluminum chloride should you add?
8.56 grams
500
For the following reaction, 6.96 grams of barium chloride are mixed with excess potassium sulfate. The reaction yields 7.26 grams of barium sulfate.
barium chloride (aq) + potassium sulfate (aq) barium sulfate (s) + potassium chloride (aq)
What is the theoretical yield of barium sulfate ?
What is the percent yield of barium sulfate ?
Theoretical: 7.80g
percent yield:93%
BaCl2 (aq) + K2SO4 (aq) BaSO4 (s) + 2KCl (aq)
- % yield= actual yield/ theoretical x100
500
A bomb calorimeter, or a constant volume calorimeter, is a device often used to determine the heat of combustion of fuels and the energy content of foods.
In an experiment, a 1.0030 g sample of adipic acid (C6H10O4) is burned completely in a bomb calorimeter. The calorimeter is surrounded by 1.330×10^3 g of water. During the combustion the temperature increases from 24.52 to 27.66 °C. The heat capacity of water is 4.184 J g-1°C-1.
The heat capacity of the calorimeter was determined in a previous experiment to be 750.4 J/°C.
Assuming that no energy is lost to the surroundings, calculate the molar heat of combustion of adipic acid based on these data.
C6H10O4(s) + (13/2) O2(g) 
5 H2O(l) + 6 CO2(g) + Energy
Molar mass 146
-2889 kJ/mol
500
Use the molecular orbital energy diagram below to answer the questions about bond order for the positive ion F2+.
Number of bonding and number of antibonding, and bond order
number of bonding: 10
number of antibonding:7
bond order: 1/2 (10 bonding electrons - 7 antibonding electrons) = 1.5
500
What volume of hydrogen gas is produced when 41.2 g of sodium reacts completely according to the following reaction at 25 °C and 1 atm?
sodium (s) + water(l)---> sodium hydroxide (aq) + hydrogen(g)
21.9 L
500
Rank the following diatomic species of carbon in order of bond length and bond strength.
C2, C2+, C2-
Bond length:
longest: C2+, C2, Shortest: C2-
Bond strength: C2-, C2, C2+