Topic9 graded practice

IB SL Chem Topic 9: Redox Reactions Graded Practice Name: ________________________________ Due on : May 10, 2023 1. A voltaic cell is constructed from zinc and copper half-cells. Zinc is more reactive than copper. Which statement is correct when this cell produces electricity? A. Electrons flow from the copper half-cell to the zinc half-cell. B. The concentration of Cu 2+ (aq) increases. C. Electrons flow through the salt bridge. D. Negative ions flow through the salt bridge from the copper half-cell to the zinc half-cell. 2. Which is a correct statement for the reaction below? 2MnO 4 - (aq) + 6H + (aq) + 5NO 2 - (aq) → 2Mn 2+ (aq) + 5NO 3 - (aq) + 3H 2 O(l) A. MnO 4 - is the reducing agent and the oxidation number of Mn increases. B. MnO 4 - is the oxidizing agent and the oxidation number of Mn decreases. C. NO 2 - is the reducing agent and the oxidation number of N decreases. D. NO 2 - is the oxidizing agent and the oxidation number of N increases. 3. Iron is a stronger reducing agent than silver. What is correct when this voltaic cell is in operation? 4. What is correct in an electrolytic cell? 5. The diagram shows an unlabeled voltaic cell for the reaction: Pb 2+ (aq) + Ni(s) → Ni 2+ (aq) +Pb (s) Label the diagram with the species in the equation. Suggest a metal that could replace nickel in a new half-cell and reverse the electron flow. Use section 25 of the data booklet. 1 | P a g e

IB SL Chem Topic 9: Redox Reactions Graded Practice 6. What is the order of decreasing reactivity of the metals (most reactive first)? Zn(s) + Sn 2+ (aq) → Zn 2+ (aq) + Sn(s) Cu(s) + Zn 2+ (aq) → No Reaction Sn(s) + Cu 2+ (aq) → Sn 2+ (aq) + Cu(s) Ag(s) + Cu 2+ (aq) → No Reaction A. Zn > Cu > Sn > Ag B. Sn > Zn > Ag > Cu C. Ag > Cu > Zn > Sn D. Zn > Sn > Cu > Ag 7. What is the oxidation half-equation in the redox reaction? 2S 2 O 3 2– (aq) + I 2 (aq) → S 4 O 6 2– (aq) + 2I – (aq) A. I 2 (aq) + 2e – → 2I – (aq) B. 2I – (aq) → I 2 (aq) + 2e – C. 2S 2 O 3 2– (aq) → S 4 O 6 2– (aq) + 2e – D. S 4 O 6 2– (aq) + 2e – → 2S 2 O 3 2– (aq) 8. Which statements are correct for a voltaic cell? I.A spontaneous redox chemical reaction produces electrical energy. II. Oxidation occurs at the cathode (negative electrode). III. Electrons flow from anode (negative electrode) to cathode (positive electrode). A. I and II only B. I and III only C. II and III only D. I, II and III 9. Which change represents oxidation? A. HClO 4 to HClO 3 B. N 2 to NH 3 C. N 2 O to NO D. SO 4 2− to SO 3 2− 10. Which element is reduced in the following decomposition? (NH 4 ) 2 Cr 2 O 7 (s) → N 2 (g) + Cr 2 O 3 (s) + 4H 2 O(g) A. N B. H C. Cr D. O 11. Which of the following is not a redox reaction? A. CH 4 (g) + Cl 2 (g) → CH 3 Cl(g) + HCl(g) B. C(s) + O 2 (g) → CO 2 (g) C. 2CO(g) → CO 2 (g) + C(s) D. CH 3 COOH(aq) + NaOH(aq) → CH 3 COONa(aq) + H 2 O(l) 12. What occurs at the anode (positive electrode) during the electrolysis of molten strontium bromide? A. Formation of bromine and oxidation B. Formation of bromine and reduction C. Formation of strontium and oxidation D. Formation of strontium and reduction 13. Consider the following half-equations: I 2 (s) + 2e – ⇌ 2I – (aq) (brown) (colorless) MnO 4 – (aq) + 8H + (aq) + 5e – ⇌ Mn 2+ (aq) + 4H 2 O (l) (purple) (colorless) Which statement is correct for the reaction between KMnO 4 (aq) and KI (aq) in acidic conditions? A. MnO 4 – reduces I – to I 2 . B. I – reduces MnO 4 – to Mn 2+ . C. The colour changes from brown to purple. D. MnO 4 – is oxidized to Mn 2+ . 2 | P a g e

IB SL Chem Topic 9: Redox Reactions Graded Practice 17. A student performed displacement reactions using metals W and X and solutions of salts of metals W, X, Y and Z. The results are summarized in the table. Which of the four metals is most reactive? A. W B. X C. Y D. Z 18. What are the products of the electrolysis of molten potassium chloride, KCl(l))? 19. Oxidation and reduction reactions can have a variety of commercial uses. A student decides to build a voltaic cell consisting of an aluminum electrode, Al (s), a tin electrode, Sn (s), and solutions of aluminum nitrate, Al(NO 3 ) 3 (aq) and tin(II) nitrate, Sn(NO 3 ) 2 (aq). Electron flow is represented on the diagram. Label each line in the diagram using section 25 of the data booklet. Write the equation for the expected overall chemical reaction in (a). 4 | P a g e