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3 years ago

1. One third of the elements are classified as

Chemistry

1 answer:

serious [3.7K]3 years ago

4 0

Answer:

One third of the elements are classified as Metals.

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What is the voltage of the voltaic cell Zn|Zn2+||Cu2+|Cu at 298 K if [Zn2+] = 0.2 M and [Cu2+] = 4.0 M? Cu2+ + 2e- → Cu Eo = +0.

OLga [1]

Answer : The voltage of the voltaic cell is 1.14 V

Explanation :

From the given cell representation, we conclude that

The copper will undergo reduction reaction will get reduced. Zinc will undergo oxidation reaction and will get oxidized.

The oxidation-reduction half cell reaction will be,

Oxidation half reaction: $Zn\rightarrow Zn^{2+}+2e^-$

Reduction half reaction: $Cu^{2+}+2e^-\rightarrow Cu$

Oxidation reaction occurs at anode and reduction reaction occurs at cathode. That means, gold shows reduction and occurs at cathode and chromium shows oxidation and occurs at anode.

The overall balanced equation of the cell is,

$Zn+Cu^{2+}\rightarrow Zn^{2+}+Cu$

To calculate the $E^o{cell}$ of the reaction, we use the equation:

$E^o_{cell}=E^o_{cathode}-E^o_{anode}$

$E^o_{cell}=E^o_{(Cu^{2+}/Cu)}-E^o_{(Zn^{2+}/Zn)}$

Putting values in above equation, we get:

$E^o_{cell}=(+0.34V)-(-0.76V)$

$E^o_{cell}=1.1V$

Now we have to calculate the emf or voltage of the cell.

Using Nernest equation at 298 K :

$E_{cell}=E^o_{cell}-\frac{0.0592}{n}\log \frac{[Zn^{2+}]}{[Cu^{2+}]}$

where,

n = number of electrons in oxidation-reduction reaction = 2

$E_{cell}$ = ?

Now put all the given values in the above equation, we get:

$E_{cell}=1.1-\frac{0.0592}{2}\log \frac{0.2}{4.0}$

$E_{cell}=1.14V$

Therefore, the voltage of the voltaic cell is 1.14 V

5 0

3 years ago

At –45oC, 71 g of fluorine gas take up 6843 mL of space. What is the pressure of the gas, in kPa?

Anika [276]

The moles of fluorine present are 71/19 = 3.74
Now, we know that one mole of gas at 273 K and 101.3 kPa (S.T.P.) occupies 22.4 liters
Volume of 3.74 moles at S.T.P = 3.74 x 22.4
Volume = 83.776 L = 83,776 mL

Now, we use Boyle's law, that for a given amount of gas,
PV = constant

P x 6843 = 101.3 x 83776
P = 1,240 kPa

4 0

3 years ago

Hi can you slove this please. ..

Crank

Answer : The balanced chemical equation will be:

(i) $2K+H_2SO_4\rightarrow K_2SO_4+H_2$

(ii) $Mg(OH)_2+Zn\rightarrow Zn(OH)_2+Mg$

Explanation :

Balanced chemical equation : It is defined as the equation in which total number of individual atoms on the reactant side is equal to the total number of individual atoms on product side.

Part (i):

The balanced chemical equation will be:

$2K+H_2SO_4\rightarrow K_2SO_4+H_2$

This reaction is a single displacement reaction in which most reactive element (potassium) displaces the least reactive element (hydrogen) form their solution.

Part (ii):

The balanced chemical equation will be:

$Mg(OH)_2+Zn\rightarrow Zn(OH)_2+Mg$

This reaction is a single displacement reaction in which most reactive element (zinc) displaces the least reactive element (magnesium) form their solution.

7 0

3 years ago

Humans depend on water from various sources for different reasons. All of these sources are polluted or could be polluted to som

goldenfox [79]

Explanation:

Earth is known as the "Blue Planet" because 71 percent of the Earth's surface is covered with water. Water also exists below land surface and as water vapor in the air. Water is a finite source. The bottled water that is consumed today might possibly be the same water that once trickled down the back of a wooly mammoth. The Earth is a closed system, meaning that very little matter, including water, ever leaves or enters the atmosphere; the water that was here billions of years ago is still here now. But, the Earth cleans and replenishes the water supply through the hydrologic cycle.

please mark as brainliest

8 0

3 years ago

trees are important in maintaining air quality, because they act like a filter, drawing particles from the air

arsen [322]

Trees produce carbon dioxide. They take in carbon monoxide (what we breathe out) and cycle it back for us.

Trees are important!

5 0

3 years ago