Exam 1
True or False: The law of definite proportions applies to samples of two different compounds composed of the same elements; for example, NO and N2O2.
False: The law of MULTIPLE proportions applies to samples of two different compounds composed of the same elements; for example, NO and N2O2.
Which of the following is/are paramagnetic? select all the apply
a) Mg
b) Ti
c) Ti2+
d) Sn4+
b and c
Which of the following gives the incorrect molecular geometry?
a) NF3 Trigonal pyramidal
b) PF5 trigonal bipyramidal
c) XeF4 seesaw
d) ClF3 T-Shaped
True or False: Bomb Calorimeter has constant pressure.
False
How many protons, neutrons, and electrons are in 36Cl-?
Protons: 17
Neutrons: 19
Electrons: 18
Which of the following is NOT true? (Only one answer)
a) n = 5, l = 3, ml = –3, ms = +½ is a valid set of quantum numbers.
b) There are exactly 2 orbitals in an atom that can contain the quantum numbers n = 4, ml = 2.
c) There are exactly 3 electrons in an atom that can contain the quantum numbers n = 6, l = 1
d) There are exactly seven f orbitals that are possible in the fourth shell.
c)
Which of the following is incorrect? (One answer)
a) The boiling point of Ne is lower than the boiling point of Kr because dispersion forces generally increase with increasing polarizability.
b) The boiling point of CH3OCH3 should be lower than the boiling point of CH3CH2OH.
c) Surface tension, viscosity, boiling and melting points all increase with increasing intermolecular forces.
d) The boiling point of C7H16 should be lower than the boiling point of C4H10 because boiling point generally decreases with increasing molar mass for similar molecules.
d)
Which of the following is NOT true?
a) The following is endothermic: CO2(s) --> CO2(g)
b) If an ionic compound is dissolved in water and the solution gets colder, the process of dissolving the ionic solid in water is exothermic.
c) The following reaction is exothermic: 2 H2(g) + O2(g) --> 2 H2O(g)
d) The following reaction is endothermic: CO2(g) --> ½ O2(g) + CO(g) ∆Hrxn = 282.7 kJ
e) If the products have a higher internal energy than the reactants, then ∆Erxn is positive and energy flows from the surroundings to the system.
b)
On account of the high heat and low humidity in the summer in Death Valley, California, a visitor requires about one quart of water for every two miles traveled on foot. Calculate the approximate number of liters required for a person to walk 18.0 kilometers in Death Valley. Give your answer to 3 significant figures. HINT: 1 mile = 5280 ft; 1 ft = 0.3048 m;1 gallon = 4 quarts; 3.7854 L = 1 gallon
5.29 L
Which of the following gives the incorrect name or formula?
a) HgCl: Mercury(I) chloride
b)Na2PO4: Sodium Phosphate
c) FeSO4 * 7H2O: Iron(II) sulfate heptahydrate
d) K2Cr2O7: Potassium dichromate
b)
In which of the following reactions are the INCORRECT products given?
a) Pb(NO3)2(aq) + 2 NaI(aq) → 2 NaNO3(aq) + PbI2(s)
b) NiBr2(aq) + K2CO3(aq) → 2 KBr(aq) + NiCO3(s)
c) CaCl2(aq) + Na2SO4(aq) → CaSO4(s) + 2 NaCl(aq)
d) 2 Na3PO4(aq) + 3 Ca(OH)2(aq) → 6 NaOH(aq) + Ca3(PO4)2(s)
e)K2S(aq) + BaCl2(aq) → 2KCl(aq) + BaS(s)
e)
Which of the following is NOT true?
a) The combustion of propane is an exothermic reaction.
b) The first law of thermodynamics states that the total energy of the universe is constant.
c) Freezing water is an exothermic process.
d) This reaction is endothermic: CO2(g) --> CO(g) + ½ O2(g) ∆H = 282.7 kJ
e) If the reactants have a lower energy than the products for a reaction, ∆Erxn is negative and energy flows from the system to the surroundings.
e)
Gallium has two naturally occurring isotopes: Ga-69 (68.92558 amu) and Ga-71 (70.92470 amu). Find the mass of Ga-71 in a 4.500 g sample of naturally occurring gallium. Give your answer to 3 significant figures
1.79 grams
The table below shows consecutive ionization energies for an atom in the third row of the periodic table. What element is it? Give the symbol in the box below.
1st ionization energy: 786 kJ/mol
2nd ionization energy: 1,577 kJ/mol
3rd ionization energy: 3,232 kJ/mol
4th ionization energy: 4,356 kJ/mol
5th ionization energy: 16,091 kJ/mol
6th ionization energy: 19,805 kJ/mol
7th ionization energy: 23,780 kJ/mol
8th ionization energy: 29,287 kJ/mol
Si
What volume of 0.600 M K2CO3 is needed to completely react with 12.0 ml 0.800 M Fe(C2H3O2)3? Give your answer to 3 significant figures. 3 K2CO3(aq) + 2 Fe(C2H3O2)3(aq) -> Fe2(CO3)3(s) + 6 KC2H3O2(aq)
24.0 mL K2CO3 solution
Calculate ∆Hrxn for the reaction: C2H2(g) + 2 H2(g) --> C2H6(g).
Bond Bond Energy (kJ/mol)
C-H --> 414
C-C --> 347
C=C --> 611
C≡C --> 837
H-H --> 436
-294 kJ
An electron has a mass of 9.109 x 10–28 g and a deBroglie wavelength of 5.39 nm. Calculate its velocity in miles/hour. Give your answer using 3 significant figures. HINT: 1 mile = 1.6093 km
(deBroglie wavelength) = (h)/(m * v)
h= 6.626 x 10-34 J * s
3.02 x 105 miles/hour
Using combustion analysis, a 15.00 g sample of an unknown organic compound containing carbon, hydrogen, and oxygen produces 35.715 g CO2 and 11.246 g H2O. What is the empirical formula for the compound?
C13H20O4
A reaction vessel contains 84.03 g N2 and 104.1 g Li, which reacts to form Li3N: N2(g) + 6 Li(s) -> 2 Li3N(s)
If 142 g of LiaN is actually produced when the reaction is performed, calculate the percent yield. Give your answer with 3 significant figures.
81.5%
The combustion of benzoic acid (∆Ecombustion = –3228 kJ/mol C7H6O2) can be used to determine the heat capacity of a bomb calorimeter. A 3.05 g tablet of C7H6O2 undergoes combustion in a bomb calorimeter; the temperature of the bomb calorimeter increases from 22.1 C to 36.6 C. Calculate the heat capacity of the bomb calorimeter.
a)