Quiz 7 Name: _______________________________________ Chemistry 102, Lecture 402 – Fall 2015 DS Section: (1 point) ____________________________ 1. What are the oxidation numbers of all elements in each of the substances listed? (3 points) N + O −2 b. KNO2 K + N +3 a. N2O O −2 c. N2 N 0 2. From the list of metals to the right, what is one that will react with cadmium nitrate? (4 points) Al or Zn Al Ag Pb Zn a. Give the balanced equations as noted for this reaction: molecular equation:
Zn(s) + Cd(NO3)2(aq) → Zn(NO3)2(aq) + Cd(s) 2Al(s) + 3Cd(NO3)2(aq) → 2Al(NO3)3(aq) + 3Cd(s) oxidation half reaction: Zn → Zn2+ + 2e− Al → Al3+ + 3e− reduction half reaction: Cd2+ + 2e− → Cd net equation ionic: Zn(s) + Cd2+(aq) → Zn2+(aq) + Cd(s) oxidizing agent: Cd(NO3)2 2Al(s) + 3Cd2+(aq) → 2Al3+(aq) + 3Cd(s) reducing agent: Al / Zn 3. Fill in the blank (2 point): a. A stronger reducing agent than H2 all metals listed higher than H2 (ex. Al or Mg) b. A stronger reducing agent than NaBr NaI c. What is one metal that will react with acid but will not react with water? Co, Ni, Sn or Pb 4. Complete the table. (3 points) Solution Molar mass [MgCl2] Mass of MgCl2 Solution Vol [Cl−] MgCl2 95.21 g∙mol−1 0.125 M 0.893 g 75.00 mL 0.250 M Work: −
⎛ 0.125 mol MgCl2 ⎞ ⎛ 2 mol Cl
⎜
⎟ ⎜ 1 mol MgCl
L
⎝
⎠⎝
2
⎞
−
⎟ = 0.250 M Cl
⎠
⎛ 95.21 g MgCl2
⎛ 0.125 mol MgCl2 ⎞
( 0.07500 L ) ⎜
⎜
⎟
L
⎝
⎠
⎝ mol MgCl2
⎞
⎟ = 0.893 g MgCl 2
⎠