EXPERIMENT ELECTROCHEMISTRY 29 EQUIPMENT AND CHEMICALS: Chemical Equipment 0.5M

Question

EXPERIMENT ELECTROCHEMISTRY 29 EQUIPMENT AND CHEMICALS: Chemical Equipment 0.5M SnCl 2H20 paper 0.5M CuSO4 Volt meter 0.5M MgSO4 Watch glass 0.5M NiSO4 Cotton KNO3 Metal U-Shaped glass tubing Strips: Cu, Sn, Mg. Ni voltaic test tubes (2) INTRODUCTION: During chemical transfer can occur between reactants in solution. As a reactions, electron less positive or one of the chemicals present gain an electron (thereby taking on a ive or even even a negative charge), and the other loses an taking on a less positive charge), Electrochemistry is of chemistry that type of occurs oxidation-reduction reactions As mentioned, when a chemical reaction loses pontaneously there can be an exchange of electrons between reactants. The that electrons is said to undergo idation while the reactant that gains electrons undergoes reduction. Such reactions are termed reduction reactions or REDOX reactions for short A common REDOX reaction is that between solid zinc and aqueous copper (II) ions Dij zn (ac) Cu (s) Cu (aq) Zn (s) When solid zinc is placed into solution it starts to undergo oxidation and in the process electrons forming ons in solution. The electrons lost by zinc are picked up by the copper causing reduction to occur. The resulting solid copper begins to deposit on the of the zinc metal remaining in the solid form. Both the reduction and oxidation reactions can be expressed as "half-cell" reactions. Together they form the complete reaction. 12] Reduction Cu (aq) 2e Cu(s) [31 Oxidation Zn(s) Cu(s) +Zn (aq) +2e Zn(s) Cu (aq) 2e Notice how, in the above, the copper ion takes on electrons and its charge becomes less positive as a result. Conversely, the neutral zinc atoms lose electrons, and become positively charged. Note too that the number of electrons lost must equal the number of electrons gained in all redox reactions. Care must be taken to balance each half-cell reaction in order to ensure that the final reaction is balanced Chemistry 132 EXPERIMENT 29

Explanation / Answer

(3)

No reaction took place because copper does't have the required oxidation potential to replace Sn2+ ions from solution because Cu has higher reduction potential as compared to Sn.

(4)

Reaction took place, the blue color faded away because the Cu2+ ions in the solution were replaced by Sn2+, and the Cu was forced to be deposited as a ppt.

(5)

No cell reaction takes place in this case

(6)

Oxidation half cell:

Sn(s) -----> Sn2+ + 2e-

Reduction half cell:

Cu2+ + 2e- ------> Cu(s)

Ecell = Eoxid + Ered = -(-0.136) + 0.340 = 0.476 V

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