Page 240 - Chemistry eBook

Wire
Al(s) electrode
Salt Al(NO3)3(aq)bridgeNi(NO3)2(aq)
Ni(s) electrode
Sample Regents Questions
2Al(s) 􏰀 3Ni2􏰀(aq) → 2Al3􏰀(aq) 􏰀 3Ni(s)
Al(NO ) (aq) Ni(NO ) (aq) 33 32
72 State the direction of electron flow through the wire when the switch is closed. [1]
73 Write a balanced half-reaction equ2􏰀ation for the3o􏰀xidation that occurs when the switch is
2Al(s) 􏰀 3Ni (aq) → 2Al (aq) 􏰀 3Ni(s)
72 State the direction of electron flow through the wire when the switch is closed. [1]
closed. [1]
74 Determine the number of moles of Al(s) needed to completely react with 9.0 moles of
2􏰀
73 NWirite(aaqb) aiolannsc. ed[1h]alf-reaction equation for the oxidation that occurs when the switch is
closed. [1]
75 State, in terms of energy, why this cell is a voltaic cell. [1]
74 Determine the number of moles of Al(s) needed to completely react with 9.0 moles of P.S./Chem.–June ’12Ni2􏰀(aq) ions. [1] [11]
[OVER]
[OVER]
75 State, in terms of energy, why this cell is a voltaic cell. [1]
P.S./Chem.–June ’12 [11]
June 2012 #74
6.0 moles
Answer
Explanation:
1. Cross out any molecule not applicable
to the question. Since the question only asks about ‘Al’ and Ni2+, we cross out the other molecules.
2. Set up a proportion.
3. Solve with cross multiplication.
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