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posted by  Rell21 on 11/12/2008 8:09:21 PM  |  status: Closed  

Electrochemistry

Course Textbook Chapter Problem
General Chemistry Chemistry (9th) by Chang N/A N/A
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How many coulombs would be required to electroplate 35.0 grams of chromium by passing an electrical current through a solution containing CrCl3?
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posted by james jagan on 11/13/2008 3:04:29 AM  |  status: Live
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Response Details:
CrCl3 will dissociate into Chromium and Chloride ions. Chromium ion requires 3 electrons to change into Chromium. i.e 3 moles of electrons are required to produce one mole of  Chromium .
    CrCl3 ↔  Cr+3 + 3 Cl-
   Cr+3 + 3e- → Cr(S)
              3 mol     1 mol
  1 mole of Chromium = 51.99 g   [ Molar mass of Cr = 51.99]
   51.99 g of Chromium is producedafter taking 3 mol of electrons
 17.33 g of Chromium is producedafter taking 1 mol of electrons
 we know that 1 mol of electron represents 1 F = 96500 coulombs
  35 g of Chromium is producedafter taking  2.01 mol of electrons (35 g*1 mol/17.33 g)
 ∴ 2.01*96500 coulombs would be required to electroplate 35.0 grams of chromium by passing an electrical current through a solution containing CrCl3
 194893.248 coulombs would be required to electroplate 35.0 grams of chromium by passing an electrical current through a solution containing CrCl3
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