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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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What is the Kelvin temperature for 30°C?
Annette [7]
303.15 would be your answer 
4 0
3 years ago
Certain atoms emit photons of light with an energy of 3.820 ✕ 10−19 J. Calculate the frequency (in Hz) and wavelength (in nm) of
charle [14.2K]

Answer:

ν = 5,765x10¹⁴ Hz

λ = 520 nm

230,0 kJ/mole

Explanation:

To convert energy yo frequency you need to use:

E = hν

Where E is energy (3,820x10⁻¹⁹ J)

h is Planck's constant (6,626x10⁻³⁴ Js)

And ν is frequency, replacing ν = 5,765x10¹⁴ s⁻¹ ≡ 5,765x10¹⁴ Hz

To convert frequency to wavelength:

c = λν

Where s is speed of light (2,998x10⁸ ms⁻¹)

ν is frequency (5,765x10¹⁴ s⁻¹)

And λ is wavelength, replacing: λ = 5,200x10⁻⁷ ≡ 520 nm

If 1 photon produce 3,820x10⁻¹⁹ J, in mole of photons produce:

3,820x10⁻¹⁹ J ×\frac{6,022x10^{23}}{1 mole} = 230040 J/mole ≡ 230,0 kJ/mole

I hope it helps!

4 0
3 years ago
8. Which type of bond results when one or more valence
Gekata [30.6K]

Answer:

B

Explanation:

8 0
3 years ago
This is the process that cells reproduce and replace old or damaged cells.
Vedmedyk [2.9K]

Answer:

mitosis

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because ur a cumt who doesn't know the answer

8 0
3 years ago
Determine how many liters of hydrogen adjusted to STP there are in a 50.0 liter steel cylinder if the pressure inside is 100.0 a
Dvinal [7]

Answer : The volume of hydrogen gas at STP is 4550 L.

Explanation :

Combined gas law is the combination of Boyle's law, Charles's law and Gay-Lussac's law.

The combined gas equation is,

\frac{P_1V_1}{T_1}=\frac{P_2V_2}{T_2}

where,

P_1 = initial pressure of gas = 100.0 atm

P_2 = final pressure of gas at STP = 1 atm

V_1 = initial volume of gas = 50.0 L

V_2 = final volume of gas at STP = ?

T_1 = initial temperature of gas = 27.0^oC=273+27.0=300K

T_2 = final temperature of gas at STP = 0^oC=273+0=273K

Now put all the given values in the above equation, we get:

\frac{100.0atm\times 50.0L}{300K}=\frac{1atm\times V_2}{273K}

V_2=4550L

Therefore, the volume of hydrogen gas at STP is 4550 L.

3 0
3 years ago
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