1. Which of the following solutions will not form a precipitate when added to 0.
ID: 855767 • Letter: 1
Question
1. Which of the following solutions will not form a precipitate when added to 0.10 M BaCl2?
A- 0.10 M AgNO3
B- 0.10 M LiNO3
C- 0.10K2SO4
2. What is the oxidation number change for the manganese atom in the following unbalanced reduction half reaction:
MnO4 -(aq) + H+(aq) ? Mn2+(aq) + H2O(l)?
A. -7
B. -5
C. +7
D. +5
3. What are the coefficients in front of NO3 -(aq) and Ni(s) when the following redox equation is balanced in an acidic solution: ___ NO3 -(aq) + ___ Ni(s) ? ___ NO(g) + ___ Ni 2+(aq)?
A. 2,3
B. 2,6
C. 3,6
D. 3,4
4. The metal content of iron in ores can be determined by a redox procedure in which the sample is first oxidized with Br2 to convert all the iron to Fe3+ and then titrated with Sn2+ to reduce the Fe3+ to Fe2+. The balanced equation is
2Fe3+(aq)+Sn2+(aq)?2Fe2+(aq)+Sn4+(aq)
What is the mass percent Fe in a 0.1825gsample if 13.30mL of a 0.1015 M Sn2+solution is needed to titrate the Fe3+?
Express your answer using four significant figures.
(( on this question somehow i keep getting 73.84))
Can someone show me how to do these problems step by step please!!
Explanation / Answer
2. What is the oxidation number change for the manganese atom in the following unbalanced reduction half reaction:
MnO4 -(aq) + H+(aq) ? Mn2+(aq) + H2O(l)?
Mn goes fro +7 in MnO4- to +2 in Mn+2
therefore, gain of 5 electrons
3. What are the coefficients in front of NO3 -(aq) and Ni(s) when the following redox equation is balanced in an acidic solution: ___ NO3 -(aq) + ___ Ni(s) ? ___ NO(g) + ___ Ni 2+(aq)?
split
NO3- = NO
Ni = Ni+2
balance O
NO3- = NO + 2H2O
Ni = Ni+2
balance H
4H+ + NO3- = NO + 2H2O
Ni = Ni+2
balance charge
3e- + 4H+ + NO3- = NO + 2H2O
Ni = Ni+2 + 2e-
balance e
6e- + 8H+ + 2NO3- = 2NO + 4H2O
3Ni = 3Ni+2 + 6e-
add all
3Ni + 6e- + 8H+ + 2NO3- = 2NO + 4H2O + 3Ni+2 + 6e-
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