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iren2701 [21]
3 years ago
7

What is the oxidation number of chromium in the ionic compound ammonium dichromate (nh4)2cr2o7?

Chemistry
1 answer:
lesya692 [45]3 years ago
4 0
The oxidation number of an element is the number of electrons that are gained or lost by the element to form a chemical bond. 
the net oxidation number of the ion is its charge.
compound (NH₄)₂Cr₂O₇ is made of cation - NH₄⁺ and anion - Cr₂O₇²⁻
oxidation number of ion - -2
(oxidation number of Cr x 2 Cr atoms) +(oxidation number of O x 7 O atoms )= -2
oxidation number of Cr = y
oxidation number of O = -2
(y x 2) + (-2 x 7) = -2
2y - 14 = -2
2y = 12
y  = + 6
therefore oxidation number of Cr is +6 
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Fluorine-21 has a half life of approximately 5 seconds. You have 340 grams, what fraction of the original nuclei would remain af
madreJ [45]
The half life equation is -->P(t) = Pi (0.5) ^ (t/c)
c is equal to the element to reach its half-life (5 seconds)t is equal to the duration of time the element is expose to (20 seconds)Pi is the initial amount (340)0.5 is the base of this exponential function to represent half-life.P(t) is the expression for the function of time

P(20) = 340 (0.5)^20/5P(20) = 340 (0.5) ^4P(20)= 21.25 grams
Fraction = P(t)/Pi              = P(20)/Pi              =21.25/340              =1/16
Therefore, when given 20 seconds, 340 grams of Fluorine-21 will degrade to 21.25 grams OR 1/16 of its original mass.
Hope this method helps! (This is my answer btw, I think you may have accidentally posted twice?)
7 0
3 years ago
the radius of magnesium atom is 0.160nm. the radius of a magnesium ion is 7.2x 10^-11m. explain the difference in size between t
Allushta [10]

Answer:

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8 0
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Well,I hope it helps....

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erastova [34]

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