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2 years ago

An electrochemical cell is powered by the half reactions shown below.

1 answer:

7 0

Reduction reactions are those reactions that reduce the oxidation number of a substance. Hence, the product side of the reaction must contain excess electrons. The opposite is true for oxidation reactions. When you want to determine the potential difference expressed in volts between the cathode and anode, the equation would be: E,reduction - E,oxidation.

To cancel out the electrons, the e- in the reactions must be in opposite sides. To do this, you reverse the equation with the negative E0, then replacing it with the opposite sign.

Pb(s) --> Pb2+ +2e- E0 = +0.13 V
Ag+ + e- ---> Ag E0 = +0.80 V

Adding up the E0's would yield an overall electric cell potential of +0.93 V.

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Sodium thiosulfate, Na 2S 2O 3, is used as a "fixer" in black and white photography. Identify the reducing agent in the reaction

Tatiana [17]

Answer: Reducing agent in the given reaction is $S_{2}O^{2-}_{3}$ .

Explanation:

A reducing agent is defined as an element which tends to lose electrons to other element leading to an increase in its oxidation number.

In the given reaction, oxidation state of sulfur in $S_{2}O^{2-}_{3}$ is +2 and $I_{2}(aq)$ has 0 oxidation state.

In $S_{4}O^{2-}_{6}(aq)$ oxidation state of S is 2.5 and in $2I^{-}(aq)$ oxidation state of I is -1.

Since, an increase in oxidation state of S is occurring from +2 to +2.5. Hence, it is acting as a reducing agent.

Thus, we can conclude that reducing agent in the given reaction is $S_{2}O^{2-}_{3}$ .

8 0

2 years ago

Identify the property of the matter described below.

ZanzabumX [31]

Answer: C.

Explanation: Alcohol floats on oil and water sinks in oil. Water, alcohol, and oil layer well because of their densities, but also because the oil layer does not dissolve in either liquid. The oil keeps the water and alcohol separated so that they do not dissolve in one another. ... Water sinks because it is more dense than oil.

7 0

2 years ago

Which of the following is a pure substance

sergij07 [2.7K]

What is the following

8 0

2 years ago

How much energy is evolved during the formation of 197 g of Fe, according to the reaction below?

hoa [83]

Answer:

ΔH for formation of 197g Fe⁰ = 1.503 x 10³ Kj => Answer choice 'B'

Explanation:

Given Fe₂O₃(s) + 2Al⁰(s) => Al₂O₃(s) + 2Fe⁰(s) + 852Kj

197g Fe⁰ = (197g/55.85g/mol) = 3.527 mol Fe⁰(s)

From balanced standard equation 2 moles Fe⁰(s) => 852Kj, then ...

3.527 mole yield (a higher mole value) => (3.527/2) x 852Kj = 1,503Kj (a higher enthalpy value).

______

NOTE => If 2 moles Fe gives 852Kj (exo) as specified in equation, then a higher energy value would result if the moles of Fe⁰(s) is higher than 2 moles. The ratio of 3.638/2 will increase the listed equation heat value to a larger number because 197g Fe⁰(s) contains more than 2 moles of Fe⁰(s) => 3.527 mole Fe(s) in 197g. Had the problem asked for the heat loss from less than two moles Fe⁰(s) - say 100g Fe⁰(s) (=1.79mole Fe⁰(s)) - then one would use the fractional ratio (1.79/2) to reduce the enthalpy value less than 852Kj.

8 0

2 years ago

The Dew Point... a. is the same as temperature when the relative humidity is 100%. b. can only be given in Kelvin degrees. c. is

telo118 [61]

Answer:

Option (A)

Explanation:

The dew point refers to the temperature at which the amount of water vapor present in the air is so high that the relative humidity becomes 100%, and with the increasing rate of cooling, the condensation process takes place and dew is formed.

So for dew point to occur, the air temperature must reach a condition where the air is fully saturated or the relative humidity is 100%.

Thus, the correct answer is option (A).

6 0

2 years ago