Atomic Structure
Mathematics of Chemistry
Matter and Energy
Oxidation and Reduction
Solutions/Solubility
100
Which electron configuration represents an atom in an excited state? : (1) 2-7 (2) 2-6-2 (3) 2-8-1 (4) 2-8-8-2
(2) 2-6-2
100
Iodine is 80% (127I) 17% (126I) and 3% (128I) : Calculate the average atomic mass of iodine. :
(127 x .80) + (126 x .17) + (128 x .03) = 126.8
100
At standard pressure, which element has a freezing point at below standard temperature? : (1) In (2) Ir (3) Hf (4) Hg
(4) Hg -- * check Table S and note that standard temperature is 273K
100
Voltaic cells differ from electrolytic cells because in a voltaic cell : (1) the cathode is positively charged (2) the anode is positively charged (3) electrons flow from anode to cathode (4) electrons flow from cathode to anode
(3) electrons flow from anode to cathode
100
Which compound becomes less soluble in water as the temperature of the solution is increased? (1) HCl (2) KCl (3) NaCl (4) NH4Cl
(1) HCl * Table G
200
Which statement identifies the element arsenic? : (1) Arsenic has an atomic number of 33 (2) Arsenic has a melting point of 84K (3) An atom of arsenic in the ground state has eight valence electrons (4) An atom of arsenic in the ground state has a radius of 146 pm
(1) Arsenic has an atomic number of 33
200
What is the molarity of an H2SO4 solution if 0.25 L of the solution contains 0.75 mol of H2SO4? : (1) 0.33 M (2) 0.75 M (3) 3.0 M (4) 6.0 M
(3) 3.0 M
200
Which substance can not be broken down by a chemical change? : (1) ammonia (2) mercury (3) propane (4) water
(2) mercury
200
Given : Zn(s)+ Cu+2(aq) --> Zn+2(aq) + Cu(s) : The flow of electrons through the external circuit in this cell is from the : (1) Cu anode to the Zn cathode (2) Cu cathode to the Zn anode (3) Zn anode to the Cu cathode (4) Zn cathode to the Cu anode
(3) Zn anode to the Cu cathode
200
According to Table F, which compound is soluble in water? : (1) barium phosphate (2) calcium sulfate (3) silver iodide (4) sodium perchlorate
(4) sodium perchlorate
300
An element that is malleable and a good conductor of heat and electricity could have an atomic number of : (1) 16 (2) 18 (3) 29 (4) 35
(3) 29
300
How much water would be needed to add to a 500mL of 2.4 M KCl solution to make a 1.0 M solution?
M1V1 = M2V2 --> (2.4M)(500mL) = (1.0M)(x) = 1200mL
300
A large sample of solid calcium sulfate is crushed into smaller pieces for testing. Which two physical properties are the same for both large sample and one of the smaller pieces? (1) mass and density (2) mass and volume (3) solubility and density (4) solubility and volume
(3) solubility and density
300
In the reaction 2KCl(l) --> 2K(s) + Cl2(g), the K+ ions are : (1) reduced by losing electrons (2) reduced by gaining electrons (3) oxidized by losing electrons (4) oxidized by gaining electrons
(2) reduced by gaining electrons
300
Which amount of a compound dissolved in 100.g of water at the stated temperature represents a solution that is saturated? : (1) 20g KClO3 at 80 degree Celsius (2) 40g KNO3 at 25 degree 25 Celsius (3) 40g KCl at 60 degree Celsius (4) 60g NaNO3 at 40 degree Celsius
(2) 40g KNO3 at 25 degree 25 Celsius * Table G
400
The wave-mechanical model of the atom is required to explain the : (1) mass number and atomic number of an atom (2) organization of atoms in a crystal (3) radioactive nature of some atoms (4) spectra of elements with multielectron atoms
(4) spectra of elements with multielectron atoms * electrons are shown to be located in orbitals or energy levels that are at different locations around the nucleus-- electrons that gain enough energy can move to a higher energy level and when it returns back to the lower energy level, the energy is released as light
400
Calculate the Keq for the reaction in a 2.0L flask at 100 degree Celsius : PCl5(s) + H2O (g) <--> 2HCl (g) + POCl3(g) : .075 mol of PCl5, .050 mol of H2O, .750 mol of HCl, .500 mol of POCl3
[H2O] = .050/2L = .025M [HCl] = .750/2L = .375M [POCl3] = .500/2L = .25M Keq = ([POCl3][HCl]^2)/[H2O] = 1.40
400
When 418.joules of heat energy are added to 10.0 grams of water at 20.0 degree Celsius, the final temperature of the water will be : (1) 10.0 degree Celsius (2) 30.0 degree Celsius (3) 40.0 degree Celsius (4) 100.0 degree Celsius
(1) 10.0 degree Celsius --> q=mcT
400
Which statement describes what occurs in the following redox reaction? : Cu(s) + 2Ag+(aq)--> Cu+2(aq) + 2Ag (s) : (1) only mass is conserved (2) only charge is conserved (3) both mass and charge are conserved (4) neither mass nor charge is conserved
(3) both mass and charge are conserved
400
A saturated solution of potassium chloride at 10 degree Celsius is heated to 30 degree Celsius. As the solution is heated in a closed container, the total mass of the solution : (1) decreases (2) increases (3) remains the same
(3) remains the same
500
Explain, in terms of electrons, why the ionic radius of a Group 2 element is smaller than its atomic radius
A group 2 ion has two fewer electrons than the atom from which it was formed
500
A 170.00 g sample of an unidentified compound contains 29.84 g sodium, 67.49 g chromium, and 72.67 g oxygen. What is the compound's empirical formula?
(Na2Cr2O7) ---> Na - (29.84/170) x 100 = 17.55/23 = .76/.76 =1 Cr - (67.29/170) x100 = 39.7/52 = .76/.76 =1 O - (72.67/170) x 100 = 42.7/16 = 2.7/.76 = 3.5
500
What volume will 250.mL of gas at STP occupy if the pressure changes to 2.0 atmospheres and the temperature changes to 30 degree Celsius
138.7 mL or 139mL --> (P1V1)/T1 = (P2V2)/T2 = (1.0atm)(250mL)/(273K) = (2.0atm)(x)/(303K)
500
Given the reaction : 4Al(s) + 3O2(g) --> 2Al2O3(s) : Write the balanced oxidation half-reaction for this reaction. : What is the oxidation number of oxygen in Al2O3?
4(Al --> Al+3 +3e-)- 3(O2 +4e- --> 2O-2) --> (4Al --> (4Al+3 + 12e-); Al2O3 -- oxidation number of O is -2
500
An unsaturated solution is made by completely dissolving 20.0 grams of NaNO3 in 100.0 grams of water at 20.0 degree Celsius : Determine the minimum mass of NaNO3 that must be added to this unsaturated solution to make a saturated solution at 20.0 degree Celsius. Identify one process that can be used to recover the NaNO3 from the unsaturated solution.
- 68 grams ( in Table G under 20 degree Celsius,about 88 grams of NaNO3 is needed to create a saturated solution. the solution already have 20 grams, so you subtract both number.) - evaporation or boiling the water
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