CHEM191 Test 2 Practice Questions 2021
1. What is the difference between an exothermic and endothermic reaction? Explain how the temperature of the surroundings changes with an exothermic and endothermic reaction.
2. Zinc metal reacts with an aqueous solution of hydrochloric acid to produce hydrogen gas. Suggest two ways that the reaction component could be changed in order to make the reaction produce the gas at a faster rate. Justify your answers using collision theory.
3. Explain what a catalyst is and how does it speed up a reaction
4. Identify the type of reaction is shown below?
a. Displacement
b. Exchange
c. Decomposition
d. Combination
5. The following pairs of aqueous solutions are mixed, which WILL result in the formation of a precipitate?
a. zinc sulfate + sodium chloride
b. lead nitrate + calcium chloride
c. ammonium sulfate + sodium nitrate
d. sodium chloride + lithium oxide
6. Explain why the following equation below forms Fe(OH)3 as a solid precipitate and an aqueous solution of NaCl. Justify your answer by referring to the solubility rules.
7. What is the oxidation number of each iron atom is Fe2O3?
a. +6
b. -2
c. -3
d. +3
8. In the balanced redox equation below, identify the oxidant and reductant (respectively)?
a. Mg, H2SO4
b. H2, MgSO4
c. Mg, H2
d. H2SO4, Mg
9. Which of the following is a correct expression for the equilibrium constant K for the equilibrium reaction below?
a. A
b. B
c. C
d. D
10. The equilibrium constant for the reaction,
What is the equilibrium constant for the reaction shown below under the same conditions?
a. 600
b. 4.95
c. 49
d. 0.0408
11. In the reaction below, which one of the sets below constitutes an acid-conjugate base pair?
a. H2O, H3O
+
b. H2PO4-, H2O
c. H2PO4-, H3O
+
d. H2PO4-, HPO4-2
12. Explain, using the definitions of strong and weak acids, why the picture below for Solution 3 represent strong acid and that for Solution 2 represents a weak acid
13. Identify the functional groups marked (i) to (iv) in the molecular structure given below
14. Give the systemic name (IUPAC) for the following three organic compounds
15. Identify the type of reaction occurring below:
a. Substitution
b. Oxidation
c. Addition
d. Esterification
16. Identify the type of reaction occurring below:
a. Substitution
b. Oxidation
c. Addition
d. Elimination
17. Identify the reagents A and B required to carry out the following reactions.
18. What do these hazards labels represent?
19. It is important to remove the funnel from a burette because:
a. It might hinder the reading of the burette
b. It might add impurities to the solution
c. It might add a drop of solution and change the reading
d. It might cause the burette to tip over
a. Calculate the value of ∆rH (enthalpy) of reaction for:
Using these bond enthalpies, ΔH (kJ mol-1
):
Show your working:
b. Calculate the energy absorbed when 250 g of carbon monoxide decomposes to produce carbon and oxygen. M(CO) = 28 g mol-1
c. Balance the following redox equations using the half equation method
d. The production of methane gas (CH4) from carbon and hydrogen gas is an equilibrium reaction.
Describe the effect of each of the following changes on the equilibrium concentration of methane (increase, decrease, stay the same). Justify your answers using Le Chatelier’s principles
i. H2 gas is removed
ii. Decreasing the temperature of the reaction mixture
iii. The pressure of the system is increased
e. A solution of sulfuric acid H2SO4(aq), which is a strong acid, has concentration of 0.0056 mol L-1
. Calculate the following:
i. the [OH-
] concentration (Kw = 1 x 10-14)
ii. the pH and indicate if it is acidic or basic
f. Draw the structural formula of the following organic compounds
i. 1-chloro-1-methylcyclohexane
ii. 2-methylbutanoic acid
iii. 4-ethylhexan-3-ol
g. Draw the structural formula of the monomer from which this polymer could be made.
h. The molecule pent-2-ene, CH3–CH=CH–CH2CH3, can exist as geometric isomers.
i. Draw the cis and the trans isomers below
ii. Explain why the molecule pent-2-ene has geometric isomers.
i. Write the structural formulae for Compounds 1 and 2, and give the names or formulae for Reagents, X, Y and Z.
j. Three 20.00 mL portions of sodium hydroxide, NaOH, were titrated with aqueous hydrochloric acid, HCl (aq), with concentration 0.1045 mol L-1
. The following titres were obtained: 20.26 mL, 20.27 mL and 20.32 mL.
Calculate the concentration of the sodium hydroxide solution.