1) Calculate the cell potential, at 25 C, based upon the overall reaction
Zn2+(aq) + 2 Fe2+(aq) -> Zn(s) + 2 Fe3+(aq)
if [Zn2+] = 1.50 x 10^-4 M, [Fe3+] = 0.0200 M, and [Fe2+] = 0.0100 M. The standard reduction potentials are as follows:
Zn2+(aq) + 2 e– -> Zn(s) E = –0.763 V
Fe3+(aq) + e– -> Fe2+(aq) E = +0.771 V
a. –1.665 V
b. –1.534 V
c. –1.439 V
d. –0.008 V
e. +0.008 V
Answer is B
2) Al3+ is reduced to Al(s) at an electrode. If a current of 2.75 ampere is passed for 36 hours, what mass of aluminum is deposited at the electrode? Assume 100% current efficiency.
a. 9.2 x 10^–3 g
b. 3.3 x 10^1 g
c. 9.9 x 10^1 g
d. 1.0 x 10^2 g
e. 3.0 x 10^2 g
Answer is E
3) One kind of battery used in watches contains mercury(II) oxide. As current flows, the mercury(II) oxide is reduced to mercury.
HgO(s) + H2O() + 2 e– ->Hg() + 2 OH–(aq)
If 2.3 x 10^–5 amperes flows continuously for 1200 days, what mass of Hg(l) is produced?
a. 2.5 g
b. 5.0 g
c. 9.9 g
d. 13 g
e. 15 g
Answer is A
4) If a nucleus undergoes beta particle emission
a. its atomic number decreases by four and its mass number decreases by two.
b. its atomic number decreases by two and its mass number decreases by four.
c. its atomic number increases by one and its mass number is unchanged.
d. its atomic number decreases by one and its mass number increases by one.
e. its atomic number is unchanged and its mass number decreases by one.
Answer is B
5)The molar nuclear mass of fluorine-19 is 18.99840 g/mol. The molar mass of a proton is 1.007825 g/mol. The molar mass of a neutron is 1.008665 g/mol. Calculate the binding energy (in J/mol) of F-19. (c = 2.998 x 10^8 m/s)
a. 6.753 x 1012 J/mol
b. 7.131 x 1012 J/mol
c. 1.426 x 1013 J/mol
d. 8.609 x 1014 J/mol
e. 8.538 x 1014 J/mol
Answer is C
6) Lead-200 has a half-life of 21.5 hours. Starting with 3.77 mg of this isotope, how much would remain after 72 hours?
a. 0.0 mg
b. 0.098 mg
c. 0.37 mg
d. 0.47 mg
e. 1.1 mg
Answer is C
3 answers
I agree with 3.
I agree with 5 and 6.
1 answer