Exam 2 Flashcards
When water evaporates, a chemical reaction occurs. This statement is
1. true
2. false
because
3. when water evaporates, the atoms are rearranged to make a new chemical species
4. when water evaporates, intermolecular forces are overcome but the water molecules remain intact
a) 1 and 3
b) 1 and 4
c) 2 and 3
d) 2 and 4
d) 2 and 4
false because when water evaporates, intermolecular forces are overcome but the water molecules remain intact
which acid-base theory can be used to describe this reaction: KOH + HBr –> KBr + H2O
- Arrhenius
- Bronsted-Lowry
- Lewis
a) 1 ony
b) 2 only
c) 3 only
d) 1 and 2
e) 2 and 3
f) 1, 2, and 3
f) 1, 2, and 3
Compare a dilute solution of a strong acid and a concentrated solution of a weak acid. Which will have the lower pH?
a) dilute strong acid
b) concentrated weak acid
c) the pH will be the same for both solutions
d) it is impossible to say from the information given
d) it is impossible to say from the information given
what molecular or structural feature is common to all Lewis bases?
a) a negative charge
b) a hydroxide group
c) an empty orbital that can accept a pair of electrons
d) a pair of valence electrons available for donation
d) the ability to expand its valence shell to make room for more electrons
d) a pair of valence electrons available for donation
according to the Bronsted-Lowry theory, why does the reaction shown below happen?
HBr + H2O –> H3O+ + HBr-
a) water is a base and donates a pair of electrons to the acidic hydrogen
b) the partial negative charge on the oygen is attracted to the partial positive charge on the acidic hydrogen
c) the acid donates a proton and the base accepts the proton
d) the concentration of water is always 55.5M
b) the partial negative charge on the oxygen is attracted to the partial positive charge on the acidic hydrogen
A 0.01 M solution of an acid HX has a pH of 2.5. What does that tell you about this acid?
- it is completely ionized
- it is not completely ionized
- it is a strong acid
- it is a weak acid
a) 1 and 3
b) 1 and 4
c) 2 and 3
d) 2 and 4
d) 2 and 4
what is the percent ionization of the HX solution with a pH of 2.5?
a) 0%
b) 0.32%
c) 32%
d) 40%
e) 100%
c) 32%
Compare CH3OH and CF3OH. Which would you predict to be the strongest acid and why?
a) CF3OH because you can draw resonance structures for the conjugate base
b) CF3OH because the negative charge is spread over the conjugate base by the electronegative fluorine atoms
c) CH3OH because it is a strong acid
d) CH3OH because it has the weakest conjugate base\
e) CH3OH because it contains more hydrogen atoms
b) CF3OH because the negative charge is spread over the conjugate base by the electronegative fluorine atoms
Ammonia will react with water to produce the ammonium ion and the hydroxide ion: NH3 + H2O NH4+ + -OH
which direction does the equilibrium lie?
a) to the left
b) to the right
c) in the middle
a) to the left
what is the pH of a 0.2M solution of NaOH?
a) 0.7
b) 6.3
c) 7.0
d) 13.3
e) 14.0
d) 13.3
A reaction has an enthalpy change of -105kJ. Which of the following statements are true?
- the reaction is endothermic
- the reaction is exothermic
- the strength of the bond in the products are greater than in the reactants
- the strength of the bonds in the reactants are greater than in the products
a) 1 and 3
b) 1 and 4
c) 2 and 3
d) 2 and 4
c) 2 and 3
according to Bronsted-Lowry theory, the conjugate base of HCO3- is
a) H2CO3
b) -OH
c) H2O
d) CO3^2-
d) CO3^2-
Which statement correctly descries the following reaction?
N2 + 3H2 –> 2NH3
a) this is a redox reaction in which nitrogen is oxidized and hydrogen is reduced
b) this is a redox reaction in which nitrogen is reduced and hydrogen is oxidized
c) this is a redox reaction in which the formal charges for nitrogen and hydrogen change
d) this is an acid base reaction in which nitrogen acts as the base and hydrogen acts as the acid
e) this is an acid base reaction in which nitrogen acts as the acid and hydrogen acts as the base
b) this is a redox reaction in which nitrogen is reduced and hydrogen is oxidized
which is the stronger base in water, NH2^- or -OH?
a) NH2-, because the negative charge is delocalized making the nitrogen more willing to accept a proton
b) NH2-, because the nitrogen is less electronegative and cant hold the negative charge as well as oxygen
c) -OH, because the negative charge is delocalized making the oxygen more willing to accept a proton
d) -OH, because oxygen is less electronegative and cant hold the negative charge as well as nitrogen
b) NH2-, because the nitrogen is less electronegative and cant hold the negative charge as well as oxygen
- 0 grams of HNO3 (a strong acid) are dissolved in enough water to make 2.0L of solution. What is the pH of the solution?
a) 0.18
b) 1.07
c) 1.32
d) 1.62
d) 1.62
What volume of 0.50 M HBr is necessary to completely react with 10 grams of Mg(OH)2? _ HBr + _ Mg(OH)2 --> _ MgBr2 + _ H2O a) 42.9 mL b) 146 mL c) 343 mL d) 686 mL
d) 686 mL
What is the enthalpy change for the reaction shown below? CO2 + 2H2O –> CH4 + 2O2
a) -1806 kJ
b) 355 kJ
c) 810 kJ
d) 1806 kJ
e) 5118 kJ
f) -810 kJ
c) 810 kJ
