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3 years ago

Which one of the following is an oxidation-reduction reaction?

Chemistry

2 answers:

kupik [55]3 years ago

7 0

Answer:

CH4 + 2 O2 --> CO2 + 2 H2O

Explanation:

CH4 + 2 O2 --> CO2 + 2 H2O is the only reaction where an element (oxygen) undergoes a change in oxidation state. In this reaction oxygen changes disproportionately to O⁻². That is ...

O₂ → CO₂ + 4e⁻ ==> oxidation

O₂ + 4e⁻ → H₂O ==> reduction

2O₂ + 4e⁻ → CO₂ + H₂O + 4e⁻ ==> Net oxidation-reduction

=> 4e⁻ gained by one mole O₂ in formation of CO₂ = 4e⁻ lost by the other mole O₂ in forming H₂O.

Then...

Including CH₄ (whose elements do not undergo changes in oxidation states) requires doubling reaction to balance by mass thus giving ...

2CH₄ + 2O₂ + 8e⁻ → 2CO₂ + 2H₂O + 8e⁻

Cancelling 8 reduction electrons on left with 8 oxidation electrons on right gives...

2CH₄ + 2O₂ → 2CO₂ + 2H₂O

ivann1987 [24]3 years ago

4 0

Answer:

CH₄ + 2O₂ ⟶ CO₂ + 2H₂O

Explanation:

To identify an oxidation-reduction reaction, you must determine the oxidation number of every atom involved in the reaction and see if it changes.

The only reaction where two elements change oxidation number is the oxidation of methane.

Here's the oxidation number of every atom involved:.

$\stackrel{\hbox{-4}}{\hbox{C}}\stackrel{\hbox{+1}}{\hbox{H}}_{4} +\stackrel{\hbox{0}}{\hbox{O}}_{2} \, \longrightarrow \, \stackrel{\hbox{+4}}{\hbox{C}}\stackrel{\hbox{-2}}{\hbox{O}}_{2} + \stackrel{\hbox{+1}}{\hbox{H}}_{2}\stackrel{\hbox{-2}}{\hbox{O}}$

We see that some elements change oxidation numbers.

C: -4 ⟶ +4; increase in oxidation number = oxidation

O: 0 ⟶ -2; decrease in oxidation number = reduction

H: +1 ⟶ +1; no change.

The reaction is an oxidation-reduction reaction, because carbon is oxidized, and oxygen is reduced.

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A certain first-row transition metal ion forms many different colored solutions. When four coordination compounds of this metal,

RideAnS [48]

Answer:

See explanation

Explanation:

From the analysis we have in the question, we must look towards a first row transition metal ion having a d^6 configuration because it yields a paramagnetic complex having four unpaired electrons and a diamagnetic complex having no unpaired electrons.

We have two possible candidates in mind, Fe^2+ and Co^3+. However, Fe^2+ does not form as many coloured complexes as stated in the question so we have to eliminate that option.

We are now left with only Co^3+. Various ligands are going to cause these various colours of Co^3+ to appear in solution.

Hence, we can deduce from all these that the nature of ligands determines the colour of the complex . Don't forget that the colour of a complex arises from crystal field splitting.

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3 years ago

If the symbol X represents a central atom, Y represents outer atoms, and Z represents lone pairs on the central atom, the struct

Inessa05 [86]

Answer:

The correct option is: bent 109°

Explanation:

Covalent molecules are the molecules in which the atoms are linked by covalent bonds. The electrons involved in the formation of a covalent bond are known as shared pair or bond pair of electrons.

The three-dimensional arrangement of the atoms of a molecule in space is known its molecular structure or geometry.

Given molecule: XY₂, having two lone pairs around the central atom X.

Since the molecule XY₂ has two lone pairs and two bond pairs of electrons. Therefore according to the VSEPR theory, the given molecule has a bent molecular geometry with 109° bond angle.

7 0

4 years ago

What fraction of a Sr-90 sample remains unchanged after 87.3 years

jolli1 [7]

The answer is 1/8.

Half-life is the time required for the amount of a sample to half its value.
To calculate this, we will use the following formulas:
1. $(1/2)^{n} = x$ ,
where:
n - a number of half-lives
x - a remained fraction of a sample

2. $t_{1/2} = \frac{t}{n}$
where:
 $t_{1/2}$ - half-life
t - total time elapsed
n - a number of half-lives

The half-life of Sr-90 is 28.8 years.
So, we know:
t = 87.3 years
 $t_{1/2}$ = 28.8 years

We need:
n = ?
x = ?

We could first use the second equation, to calculate n:
If:
$t_{1/2} = \frac{t}{n}$ ,
Then:
$n = \frac{t}{ t_{1/2} }$
⇒ $n = \frac{87.3 years}{28.8 years}$
⇒ $n=3.03$
⇒ n ≈ 3

Now we can use the first equation to calculate the remained amount of the sample.
 $(1/2)^{n} = x$
⇒ $x=(1/2)^3$
⇒ $x= \frac{1}{8}$

8 0

4 years ago

Which of the following is a possible Noble gas notation?

denis23 [38]

C.) [Ar] 4s23d104p2

i just took the quiz and this was the correct answer :-)

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3 years ago

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dezoksy [38]

I believe the answer is D

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