Quiz 7 Name: _______________________________________ Chemistry 102, Lecture 401 – Fall 2016 DS Section: (1 point) ____________________________ 1. What is one metal that will react with hydrochloric acid? There are many answers which are weaker oxidizing agents than HCl(aq); we will use magnesium here. Complete the table below for this reaction. (6 points) Balanced equations Macroscopic/Particle representation Oxidation half‐reaction: Mg(s)  Mg2+(aq) + 2e– Cl-
Reduction half‐reaction: 2H+(aq) + 2e–  H2(g) Also fine: 2HCl(aq) + 2e–  H2(g) + 2Cl–(aq) Overall balanced equation: 2H+(aq) + Mg(s)  H2(g) + Mg2+(aq) Also fine: 2HCl(aq) + Mg(s)  H2(g) + MgCl2(aq) # of electrons transferred ClMg2+
H2
(formed on the surface
of Mg(s) - not shown)
oxidizing agent reducing agent Spectator ion(s) HCl Mg Cl– 2 2. Is bromine (Br2(l)) oxidizing agent? Why or why not? (1 point) Yes, it is because Br2 will undergo reduction when forming Br–. 3. Complete the table. (3 points) Solution Molar concentration of solution Mass of solute (in g) Volume of Solution (in mL) Molar concentration of chloride ion MgCl2(aq) 0.103 M 0.8612 g 88.2 mL 0.205 M Solute: MgCl2 Solvent: H2O Work:  0.205 mol Cl   1 mol MgCl 2 


  0.103 M MgCl 2

L

  2 mol Cl 
 mol MgCl2  
L
 0.8612 g MgCl2  

 95.21 g MgCl 2   0.103 mol MgCl2
  1000 mL 

  88.2 mL
L


4. What mass (g) of nitrogen occupies 15.0 L at STP? (1 point) PV  nRT
n
1 atm 15.0 L 
PV

 0.770 mol
L  atm 
RT 
 0.08206
  273 K 
mol  K 

 28.02 g N 2
 mol N 2
 0.770 mol N 2  

  18.8 g 