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alex41 [277]
3 years ago
10

Consider an atom that has an electron in an excited state. The electron falls to a lower energy level. What effect does that hav

e on the electron?
A.
The electron releases energy in the form of light.
B.
The electron absorbs energy in the form of light.
C.
The electron retains its energy without any change.
D.
The electron transfers its energy to other electrons.
Chemistry
2 answers:
Rus_ich [418]3 years ago
6 0

Answer:

Correct answer is A

Explanation:

i did the test :)

irinina [24]3 years ago
3 0

On absorbing energy, an electron moves to an excited state (unstable state) from its ground state (stable state).  Since the electron is in unstable state so it tends to rearrange itself to return to its lowest energy state.  On returning to lowest energy state which is stable, it releases energy in the form of light.

Hence, option A that is the electron releases energy in the form of light on falling to lower energy state from excite state.

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<em><u>calculation</u></em>

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  Cl  is  reduce   from oxidation  state 0 to -1 therefore  the ∈°red = +1.36 V

cell  potential is therefore = +1.36 v -- 3.04  = + 4.40 V

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1. Which of the following is a correctly written thermochemical equation?
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Hard water often contains dissolved Ca2+ and Mg2+ ions. One way to soften water is to add phosphates. The phosphate ion forms in
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<span>5.5×10−2M in calcium chloride and 8.0×10−2M in magnesium nitrate.
What mass of sodium phosphate must be added to 1.5L of this solution to completely eliminate the hard water ion

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Calcium chloride = CaCl2

Ionization equation: CaCl2 ---> Ca (2+) + 2 Cl (-)

=> Molar ratios: 1 mol of CaCl2 : 1 mol Ca(2+) : 2 mol Cl(-)

Calculate the number of moles of CaCl2 in 1.5 liters of 5.5 * 10^-2 M solution

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=> 0.0825 mol Ca(2+)

2) Number of phosphate ions needed to react with 0.0825 mol Ca(2+)

formula of phospahte ion: PO4 (3-)

molar ratio: 2PO4(3-) + 3Ca(2+) = Ca3 (PO4)2

Proportion: 2 mol PO4(3-) / 3 mol Ca(2+) = x / 0.0825 mol Ca(2+)

=> x = 0.0825 coml Ca(2+) * 2 mol PO4(3-) / 3 mol Ca(2+) = 0.055 mol PO4(3-)

3) Content of Mg(2+) ions

Ionization equation: Mg (NO3)2 ----> Mg(2+) + 2 NO3 (-)

Molar ratios: 1 mol Mg(NO3)2 : 1 mol Mg(2+) + 2 mol NO3(-)

number of moles of Mg(NO3)2 in 1.5 liter of 8.0 * 10^-2 M solution

n = M * V = 8.0 * 10^ -2 M * 1.5 liter = 0.12 moles Mg(NO3)2

ions of Mg(2+) = 0.12 mol Mg(NO3)2 * 1 mol Mg(2+) / mol Mg(NO3)2 = 0.12 mol Mg(2+)

4) Number of phosphate ions needed to react with 0.12 mol Mg(2+)

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=> x = 0.12 * 2/3 mol PO4(3-) = 0.16 mol PO4(3-)

5) Total number of moles of PO4(3-)

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=> 0.215 mol PO4(3-) : 0.215 mol Na3PO4

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=> mass in grams = 0.215 mol * 164 g/mol = 35.26 g

Answer: 35.26 g of sodium phosphate
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5 0
3 years ago
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