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3 years ago

What is the oxidation number of chromium in k2cr2o7

Chemistry

1 answer:

notka56 [123]3 years ago

3 0

Answer:

The oxidation state of chromium in K₂Cr₂O₇ is 6⁺ (i.e. + 6).

Explanation:

You can calculate the oxidation number of most elements following some simple rules.

This is how you do it for chromium in K₂Cr₂O₇.

1) Rule: in a neutral compound the net oxidation number is zero (0).

Hence, sum of the oxidation numbers of K, Cr and O in K₂Cr₂O₇ is 0.

2) Rule: The most common oxidation number of oxygen in compounds, except in peroxides, is 2 ⁻ (negative 2).

3) Rule: the most common oxidation state of alkali metals is 1⁺ (positive 1)

4) Rule: multiply each oxidation state by the corresponding number of atoms in the compound (the subscripts)

2(1⁺) + 2(x) + 7(2⁻) = 0

↑ ↑ ↑

K Cr O

2 + 2x - 14 = 0

2x - 12 = 0

2x = 12

x = 6

Hence, the oxidation number of chromium in this compound is 6⁺.

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The reaction of pyrrole with bromine forms predominantly __________. View Available Hint(s) The reaction of pyrrole with bromine

xenn [34]

Answer:

a) 2-bromopyrrole

Explanation:

Our options for this questions are:

a) 2-bromopyrrole

b) 2,3-dibromopyrrole

c) N-bromopyrrole

d) 3-bromopyrrole

To understand how the reaction works we have to start with the resonance structures. (Figure 1), on these structures, we will obtain a negative charge on carbon 2 in the pyrrole ring, therefore on this carbon we can generate an attack to an electrophile.

The second step is to check how the mechanism take place. An electrophile is generated by the $Br_2$ and $FeBr_3$ . This electrophile can be attacked by the negative charge on carbon 2 producing the 2-bromopyrrole. (See figure 2).

I hope it helps!

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3 years ago

Which statement is FALSE? a. ΔHrxn is the heat of reaction. b. ΔErxn is a measure of heat. c. An exothermic reaction gives heat

Pavlova-9 [17]

Answer:

b. ΔE rxn is a measure of heat

Explanation:

a. ΔHrxn is the heat of reaction. TRUE. ΔHrxn or change in enthalpy of reaction is per definition the change in heat that is involved in a chemical reaction.

b. ΔErxn is a measure of heat. FALSE. Is the change in internal energy of a reaction

c. An exothermic reaction gives heat off heat to the surroundings. TRUE. An exothermic reaction is a chemical reaction that releases heat.

d. Endothermic has a positive ΔH. TRUE. When a process is exothermic ΔH<0 and when the process is endothermic ΔH>0

e. Enthalpy is the sum of a system's internal energy and the product of pressure and volume. TRUE. Under constant pressure and volume the formula is ΔH = ΔE + PV

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3 0

3 years ago

Neutralizing an olympic size swimming pool is conceptually very similar to performaing a massive titration experiment. Suppose a

MrRissso [65]

Answer:

6,97x10⁻³ gallons

Explanation:

pH is defined as:

pH = -log [H⁺]

Thus, you need to have, in the end:

10⁻⁷ = [H⁺]

And you have, in the first:

$10^{-9,33}$ = [H⁺]

The volume of swimming pool is:

700'000 galllons × $\frac{3,78541 L}{1 gallon}$ = 2649787 L

Thus, the moles of H⁺ in the first and in the end are:

First:

$10^{-9,33}mol/L$ × 2649787L = 1,24x10⁻³ moles

End:

$10^{-7}mol/L$ × 2649787L = 0,265 moles

Thus, the moles of H⁺ you need to add are:

0,265 - 1,24x10⁻³ = 0,26376 moles

These moles comes from 10M HCl, thus, the volume in gallons you need to add are:

$0,26376moles*\frac{1L}{10moles}* \frac{1gallon}{3,78541L}$ =

6,97x10⁻³ gallons

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4 years ago

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Dima020 [189]

Explanation:

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yaroslaw [1]

Answer:

Lonic.an electron will be transferred from potassium to the chlorine atom

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