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SSSSS [86.1K]
4 years ago
13

An element has an atomic number of 78. the number of protons and electrons in a neutral atom of the element would be _____.

Chemistry
1 answer:
Maurinko [17]4 years ago
5 0

78 and 78. An atom of the element has 78 electrons and 78 protons.

The atomic number is 78, so the atom has 78 protons (+).

If the atom is neutral, it must contain 78 electrons (-).

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What is the reduction potential of a hydrogen electrode that is still at standard pressure, but has ph = 5.65 , relative to the
Zigmanuir [339]

Answer:

\boxed{\text{-0.275 V}}

Explanation:

We must use the Nernst equation

E = E^{\circ} - \dfrac{RT}{zF} \ln Q

1. Write the equation for the cell reaction

If you want the reduction potential, the pH 5.65 solution is the cathode, and the cell reaction is

                                                                     <u> E°/V</u>

  Anode: H₂(1 bar) ⇌ 2H⁺(1 mol·L⁻¹) + 2e⁻;     0

Cathode: <u>2H⁺(pH 5.65) + 2e⁻ ⇌ H₂(1 bar)</u>;    <u> 0 </u>

 Overall: 2H⁺ (pH 5.65) ⇌ 2H⁺(1 mol·L⁻¹);      0

Step 2. Calculate E°

(a) Data

   E° = 0

   R = 8.314 J·K⁻¹mol⁻¹

   T = 25 °C

   n = 2

   F = 96 485 C/mol

pH = 5.65

Calculations:  

T = 25 + 273.15 = 298.15 K

\text{H}^{+} = 10^{\text{-pH}} = 2.24 \times 10^{-5}\text{ mol/\L}\\\\Q = \dfrac{\text{[H}^{+}]_{\text{prod}}^{2}}{\text{[H}^{+}]_{\text{react}}^{2}} = \dfrac{(1.00)^{2}}{(2.24 \times 10^{-5})^{2}} =2.00 \times 10^{9}\\\\\\E = 0 - \left (\dfrac{8.314 \times 298.15 }{2 \times 96485}\right ) \ln{2.00 \times 10^{9}}\\\\= -0.01285 \times 21.41 = \textbf{-0.275 V}\\\text{The cell potential for the cell as written is }\boxed{\textbf{-0.275 V}}

6 0
3 years ago
I need help with this question I don’t understand it at all!!!
bezimeni [28]

Answer:

C-14 => N-14 + β⁻

Explanation:

C-14 over time decays by beta emission to N-14. Before decay, C-14 nucleus contains 6 protons and 8 neutrons. It is accepted that a neutron (n°) is composed of 1 proton (p⁺) and 1 electron (e⁻). Beta emission indicates loss/discharge of a high energy e⁻ from the nucleus of C-14 leaving 7 protons and 7 neutrons. The number of protons defines the element, N-14 as a product of the decay process with the β particle (high energy electron) the other. To check, remember, the ∑mass Reactants = ∑mass Products (superscript numbers) and ∑reactant charges = ∑product charges (subscript numbers

₆C¹⁴ => ₇N¹⁴ + ₋₁e°  or, C-14 => N-14 + β

4 0
3 years ago
The electromagnetic waves consist of vibrating electric and _____ fields.
GaryK [48]

Answer:

Magnetic

Explanation:

Usually if you look the question up on Google or something you can find a Quizlet that has all the answers

5 0
3 years ago
when an animal behaviorist attempts to explain or interpret her observations, she is_______. a. classifying her data b.making an
balandron [24]

Answer:

\\  \\  \\  \\  \\  \\  \\  \\  \\  \\  \\  \\

4 0
2 years ago
Volcano formation is directly related to plate tectonics. <br><br><br> True<br> False
pashok25 [27]
I think it is True because when the plates collide then a volcano forms. (Subduction Zone)
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