CHEM 121 ACTUAL EXAM QUESTIONS WITH COMPLETE ACCURATE ANSWERS || GRADED A+ < UPDATED VERSION >
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Course
CHEM 121
Institution
CHEM 121
CHEM 121 ACTUAL EXAM QUESTIONS WITH COMPLETE ACCURATE ANSWERS || GRADED A+
< UPDATED VERSION >
1.) Which of the following solutions will form a precipitate when mixed?
1. KNO3(aq) and FeSO4(aq)
2. Na3PO4(aq) and Ni(NO3)2(aq)
3. NaCl(aq) and AgNO3(aq)
A) 2
B) 2 and 3
C) 1 and 2
D)...
CHEM 121 ACTUAL EXAM QUESTIONS
WITH COMPLETE ACCURATE ANSWERS
|| GRADED A+
< UPDATED VERSION >
1.) Which of the following solutions will form a precipitate when
mixed?
1. KNO3(aq) and FeSO4(aq)
2. Na3PO4(aq) and Ni(NO3)2(aq)
3. NaCl(aq) and AgNO3(aq)
A) 2
B) 2 and 3
C) 1 and 2
D) 3
E) 1, 2 and 3 - ANSWER ✔ B
2.) Given the following reactions
2S (s) + 3O2 (g) → 2SO3 (g) ΔH = -790 kJ
S(s) + O2 (g) → SO2 (g) ΔH = -297 kJ
Find the enthalpy of the reaction in which sulfur dioxide is oxidized to
sulfur trioxide (2SO2 (g) + O2 (g) → 2SO3 (g)) - ANSWER ✔ -196 kJ
3.) A gas is heated by an electrical coil, and expands from 1.41 L to
2.10 L against an opposing pressure of 2.50 atm. What is w for the
system in Joules?
(1.00 L∙atm = 101.3J) - ANSWER ✔ -175 J
,4.) For which one of the following reactions is ΔH°rxn equal to the heat
of formation of the product?
A. N2 (g) + 3H2 (g) → 2NH3 (g)
B. (1/2) N2 (g) + O2 (g) → NO2 (g)
C. 6C (s) + 6H (g) → C6H6 (l)
D. P (g) + 4H (g) + Br (g) → PH4Br (l)
E. 12C (g) + 11H2 (g) + 11O (g) → C6H22O11 (g) - ANSWER ✔ B
5.) Calculate the energy in the form of heat (in kJ) required to change
20.0 g ice at -25.0 oC to steam at 115.0 oC.
Heat of fusion = 333 J/g; heat of vaporization = 2256 J/g;
specific heat capacities: ice =2.06 J/g oC, liquid water = 4.184 J/g oC,
steam = 2.03 J/goC - ANSWER ✔ 61.85 kJ
6.) MgO reacts with water to form Mg(OH)2. If 5.00 g MgO is
combined with 100.0 g H2O in a coffee cup calorimeter, the temperature
of the resulting solution increases from 22.3 C to 32.9C. Calculate the
enthalpy change for the reaction per mole of MgO. Assume that the
specific heat capacity of the solution is 4.18 J/gK. - ANSWER ✔ -37.5
kJ/mol
7.) Determine the heat of condensation of titanium(IV) chloride given
the enthalpies of reaction below. TiCl4(g) == TiCl4(l)
Ti(s) + 2 Cl2(g) == TiCl4( ) change in rH = -804.2 kJ
Ti(s) + 2 Cl2(g) == TiCl4(g) change in rH = -763.2 kJ - ANSWER ✔ -
41 kJ/mol
8.) Determine the enthalpy change for the oxidation of iron given the
thermochemical equations below.
4 Fe(s) + 3 O2(g) == 2 Fe2O3(s)
Fe(s) + 3 H2O(l) == Fe(OH)3(s) + 3/2 H2(g) change in rH = +160.9 kJ
H2(g) + 1/2 O2(g) == H2O(l) change in rH= -285.8 kJ
Fe2O3(s) + 3 H2O(l) == 2 Fe(OH)3(s) change in rH= = +288.6 kJ -
ANSWER ✔ -1648.4 kJ/mol
, 9.) Calculate the change in fHo for sulfur dioxide given the
thermochemical equations below.
2 S(s) + 3 O2(g) == 2 SO3(g) change in rH = -791.5 kJ
2 SO2(g) + O2(g) == 2 SO3(g) change in rH = -197.9 kJ - ANSWER ✔
-296.8 kJ/mol
10.) The value of change in H for the reaction below is -126 kJ.
2Na2O2(s) + 2H2O(l) == 4NaOH(s) + O2(g)
The amount of heat that is released by the reaction of 25.0 g of Na2O2
with water is __________ kJ. - ANSWER ✔ 20.2 kJ
11.) Which of the following are state functions? work (w), heat (q),
energy (E), enthalpy (H), pressure (P), temperature (T), volume (V). -
ANSWER ✔ E,H,P,T,V
12.) A system absorbs 1.30 kJ of heat and expands from 2.5 L to 5.6 L
against a constant pressureof 2.2 atm. What is ΔE for the system?
(1.00Latm = 101.3 J) - ANSWER ✔ 609 J
13.) A reaction takes place in 25.0g of aqueous solution with a heat
capacity of 4.184 J/goC. The reaction causes the temperature of the
solution to increase by 2.32 oC, and the reaction produces 0.250L of gas
against a constant pressure of 1.00 atm.
What is ΔH and ΔE for this reaction? - ANSWER ✔ ΔH = -243 J and
ΔE = -268 J
14.) The wavelength of light that has a frequency of 1.66 × 10^9s-1 is
__________ m.
A) 0.181
B) 5.53
C) 2.00 x 10^-9
D) 5.53 x 10^8
E) none of the above - ANSWER ✔ A
, 15.) The wavelength of a photon that has an energy of 5.25 × 10-19 J is
__________ m.
A) 3.79 × 10^-7
B) 2.64 × 10^6
C) 2.38 × 10^23
D) 4.21 × 10^-24
E) 3.79 × 10^7 - ANSWER ✔ A
16.) The frequency of light with a wavelength of 440 nm is:
A) 6.82x10^14 1/s
B) 1.57x10^-5 1/s
C) 6.82x10^5 1/s
D) 1.57x10^12 1/s
E) 7.58x10^-3 1/s - ANSWER ✔ A
17) A mole of yellow photons of wavelength 527 nm has __________
kJ of energy.
A) 165
B) 227
C) 4.56 × 10^-46
D) 6.05 × 10^-3
E) 2.74 × 10^-19 - ANSWER ✔ B
18) A Cl-Cl bond requires 58,000J/mol to break. What frequency of
light will provide enough energy to break a Cl-Cl bond? (Hint: you need
to first use the energy per mole to find the energy to break one Cl-Cl
bond)
A) 7.41x10^12
B) 1.33x10^-13
C) 1.45x10^14
D) 6.32x10^-15
E) 9.45x10^11 - ANSWER ✔ C
19.) An electron cannot have the quantum numbers n = _______, l =
_______, ml = _______.
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