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Sav [38]
3 years ago
12

Which of the following is the electron configuration of an excited atom that is likely to emit a quantum of energy?

Chemistry
1 answer:
Soloha48 [4]3 years ago
7 0

Answer: 1s2 2s2 2p6 3s1 3p1

Explanation:

Excitation of an electron is an elevation in energy level of the valence electron above the ground state electron.

When an electron gains energy, usually the outermost electron it moves from a orbital of lower energy to a orbital of higher energy, the element is in an excited state.

The electron configuration of ground state of magnesium is 1s2 2s2 2p6 3s1 3p2, when it gains energy the electronic configuration is 1s2 2s2 2p6 3s1 3p1 the excited state of Magnesium this is because the last electron moves from the 3S orbital to a higher energy orbital 3P

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Which statement accurately describes the molecule Br2?
Zinaida [17]

there are no choices of statements

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3 years ago
Which planet listed below will take the longest amount of time to orbit the sun?
Tema [17]

Answer:

Neptune takes the longest to orbit the sun because of it's distance away from the Sun.

Explanation:

5 0
3 years ago
Select the correct answer. Given: 2Al + 6HCl → 2AlCl3 + 3H2 If the chemical reaction produces 129 grams of AlCl3, how many grams
ivann1987 [24]

The reaction produces 2.93 g H₂.

M_r:                        133.34  2.016

        2Al + 6HCl → 2AlCl₃ + 3H₂

<em>Moles of AlCl₃</em> = 129 g AlCl₃ × (1 mol AlCl₃/133.34 g AlCl₃) = 0.9675 mol AlCl₃

<em>Moles of H₂</em> = 0.9675 mol AlCl₃ × (3 mol H₂/2 mol AlCl₃) = 1.451 mol H₂

<em>Mass of H₂</em> = 1.451 mol H₂ × (2.016 g H₂/1 mol H₂) = 2.93 g H₂

7 0
3 years ago
What is the pH of a 0.640 M solution of C₅H₅NHBr (Kb of C₅H₅N is 1.7 × 10⁻⁹)?
Elden [556K]

The pH of a 0.64 M solution of pyridine (C₅H₅N) is 9.52.  

<h3>What is pH ?</h3>

A figure expressing the acidity or alkalinity of a solution on a logarithmic scale on which 7 is neutral, lower values are more acid and higher values more alkaline.

The equation for the protonation of the base pyridine is the following:

C₅H₅N + H₂O ⇄ C₅H₅NH⁺ + OH⁻   (1)

Kb = 1.7 × 10⁻⁹ (Given)

To calculate the pH of the solution we need to use the following equation:

pH + pOH = 14

<em>pH = 14 - pOH</em>

     =14 - [-log[OH⁻]]

    = 14 + log[OH⁻]

Now, we need to find the concentration of the OH⁻ ions. Since pyridine is a weak base, at the equilibrium we have (eq 1):

C₅H₅N  +  H₂O  ⇄  C₅H₅NH⁺  +  OH⁻

0.64 - x                          x              x

After entering the values of [C₅H₅N] = 0.64-x, [C₅H₅NH⁺] = x, and [OH⁻] = x, into equation (2) we can find the concentration of OH⁻:

1.7 × 10⁻⁹  =[C₅H₅NH⁺]  [OH⁻]  /  [C₅H₅N]

                = x . x / 0.64-x

1.7 × 10⁻⁹ (0.64-x) - x² = 0

Solving the above quadratic equation for x, we have :

  • x₁ = -3.32 x 10⁻⁵
  • x₂ = 3.32 x 10⁻⁵

Now, We can calculate the pH, after taking the positive value, x₂, (concentrations cannot be negative) and entering into above equation :

<em />

<em>pH = </em>14 + log[OH⁻]

     = 14 + log (3.32 x 10⁻⁵)

 

     = 9.52

Therefore, the pH of the solution of pyridine is 9.52.

Find more about pH here:

brainly.com/question/8834103?referrer=searchResults

#SPJ1

3 0
2 years ago
Which part of a feedback mechanism causes change to make up for the departure from the set point? A. sensor B. effector C. respo
koban [17]
I would have to say C. Response.
5 0
3 years ago
Read 2 more answers
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