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aliya0001 [1]
3 years ago
6

How many seconds are required to produce 4.94 mg of chromium metal from an acidic solution of potassium dichromate, using a curr

ent of 0.234 a?
Chemistry
1 answer:
lyudmila [28]3 years ago
7 0
<span>Answer: The half-reaction is as followed: Cr2O72â’(aq) + 14H+ + 6e⒠→ 2Cr3+(aq) + 7H2O From the half-reaction, you can retrieve the following information: 1 mole of potassium dichromate =6 moles of e^- 6 moles of e^-=2 moles of Cr You will also need the following information: 1 mole of e^-=96,485 C and 1 mole of Cr=52.00g Calculate the number of moles that 4.94mg equates too: 4.94 mg=4.94 x 10^-3g of chromium*(1 mol/52.00g)=9.50 x 10^-5 mole of Cr How many moles of electrons are need to produce 9.50 x 10^-5 mole of Cr? Solve for moles of electrons: 9.50 x 10^-5 mole of Cr*(6 moles of e^-/2 mole of Cr)=2.85 x 10^-4 moles of e^- Whats the charge of 2.85 x 10^-4 moles of electrons? Use Faraday's constant: 2.85 x 10^-4 moles of e^-*(96,485 C/1 mole of e^-)=2.750 x 10^1 C Since current (A)=charge (C)/time (s), solve for time: A=C/s C/A=s 2.750 x 10^1 C/0.234 A=time (s) 1.18 x 10^2 s=118s=time <= 3 significant figures</span>
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Explanation:

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Now, expression for K_{p} of this reaction is as follows.

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What is the angular momentum of last electron of chromium?
damaskus [11]

Answer:

expected configuration for Cr is

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electron from 4s orbital jumps to 3d orbital to get stable configuration.

so the last electron comes in 3d orbital as filling of 3d takes place after filling of 4s orbital.

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