A chemical reaction that absorbs heat from the surroundings is said to be __________________ and has a ________________∆H at constant pressure.
a. Endothermic, positive
b. Endothermic, negative
c. Exothermic, negative
d. Exothermic, positive
2 points
2
Question 2
2.
Which statement best describes the production of a chlorine molecule according to the reaction
Cl + Cl --> Cl2
a. A bond is broken, and the reaction is exothermic.
b. A bond is broken, and the reaction is endothermic.
c. A bond is formed, and the reaction is exothermic.
d. A bond is formed, and the reaction is endothermic
2 points
2
Question 3
3.
A 1 gram sample of a substance has the largest entropy when it is in the
a. Solid state
b. Liquid state
c. Crystalline state
d. Gaseous state
2 points
2
Question 4
4.
Which diagram represents the potential energy of an exothermic reaction?
2 points
2
Question 5
5.
The specific heat capacity of lead is 0.13 J/g K. How much heat (in J) is required to raise the temperature of 15 g of lead from 22 degrees C to 37 degrees C?
a. 29 J
b. 5.8 x 10-4 J
c. -0.13 J
d. 2.0 J
2 points
2
Question 6
6.
When ammonium nitrate (NH4NO3) dissolves in water, the solution gets cold.
NH4NO3 (s) --> NH4+ (aq) + NO3- (aq)
Which of the following is true about this system?
a. The sign on the enthalpy change is +; the sign on the entropy change is +
b. The sign on the enthalpy change is -; the sign on the entropy change is –
c. The sign on the enthalpy change is +; the sign on the entropy change is –
d. The sign on the enthalpy change is -; the sign on the entropy change is +
e. There is no change of enthalpy, the but the sign on the entropy change is +
2 points
2
Question 7
7.
S will be positive for the reaction ______________________.
a. 2H2 (g) + O2 (g) --> 2H2O (g)
b. 2NO2 (g) --> N2O4 (g)
c. BaF2 (s) --> Ba2+ (aq) + 2F- (aq)
d. 2Hg (l) + O2 (g) --> 2HgO (s)
e. CO2 (g) --> CO2 (s)
2 points
2
Question 8
8.
The line that represents the enthalpy (∆H) of this reaction is:
a. I
b. II
c. II + III
d. III
e. III-II
2 points
2
Question 9
9.
What is the value of the activation energy of this reaction?
a. 100 kJ
b. 200 kJ
c. 300 kJ
d. 400 kJ
e. 500 kJ
2 points
2
Question 10
10.
Below is a liquid. Complete the model by drawings particles with higher entropy. Include a key and an equal number of particles.
2 points
2
Question 11
11.
The formation of Carbon dioxide is shown below.
C + O2 --> CO2
What are the intermediates of the reaction above? Label is on the diagram below.
2 points
2
Question 12
12.
Calculate the total bond energy in the molecule below.
2 points
2
Question 13
13.
Which metal will show the greatest temperature increase if 50 J of heat is supplied to an equal mass sample of each metal?
A) Cu
B) Ag
C) Au
D) Pt
E) Fe
2 points
2
Question 14
14.
A 58-gram sample of water has an initial temperature of 32°C. After the sample absorbs 2000 joules of heat energy, the final temperature of the sample is…. (hint specific heat of water is 4.18 J/gxC)
Round to the nearest degree.
2 points
2
Question 15
15.
Calculate the specific heat capacity of a new alloy if a 15.4 g sample absorbs 393 J when it is heated from 0.0 degrees C to 37.6 degrees C.