Chemistry, 06.08.2019 06:10 jesusmojica25

How many coulombs are required to plate a layer of chromium metal 0.28 mm thick on an auto bumper with a total area of 0.40 m2 from a solution containing cro2−4? the density of chromium metal is 7.20 g/cm3.

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Answer from: kittybatch345

Explanation:

The given data is as follows.

Thickness = 0.28 mm = $0.28 \times \frac{1}{10}$ cm = 0.028 cm

Area = 0.40 $m^{2}$ = $0.40 \times 10^{4} cm^{2}$ = 4000 $cm^{2}$

As, it is known that volume = area × thickness

So, Volume = $4000 cm^{2} \times 0.028 cm$

= 112 $cm^{3}$

As density is mass divided by volume. So, mass of chromium will be calculated as follows.

Density = $\frac{mass}{volume}$

7.20 $g/cm^{3}$ = $\frac{mass}{112 cm^{3}}$

mass = 806.4 g

As, mass of 1 mole of chromium is 52 g. So, number of moles in 806.4 g of chromium will be as follows.

No. of moles = $\frac{mass}{molar mass}$

= $\frac{806.4 g}{52 g}$

= 15.50 mol

In chromate ion, ( $CrO^{2-}_{4}$ ) charge on Cr is +6. It means that 6 electrons are needed to reduce $Cr^{+6}$ into Cr.

As, 1 mole of $Cr^{+6}$ ions require 6 moles of electrons. Therefore, moles of electrons for 15.50 mol will be calculated as follows.

6 × 15.50 mol = 93.04 mol

To calculate number of electrons we multiply number of moles by Avogadro's number as follows.

$93.04 mol \times 6.02 \times 10^{23}$

= $560.13 \times 10^{23}$

= $5.6 \times 10^{25}$ electrons

There is magnitude of $6.241 \times 10^{18}$ times the charge on an electron is equal to 1 coulomb.

Hence, number of coulombs will be as follows.

No. of coulombs = $\frac{5.6 \times 10^{25}}{6.241 \times 10^{18}}$

= $0.897 \times 10^{7}$ C

or, = $8.97 \times 10^{6}$ C

Thus, we can conclude that $8.97 \times 10^{6}$ C are required to plate a layer of chromium metal with given data.

Answer from: Quest

I️i️ is a really time of to get go back home alone to the sleep

Answer from: Quest

V=s/t 4.5 = 5000+15000+20000+5000t=45000/4.5t=10000sto convert divide by 360answer is 3 hours

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How many coulombs are required to plate a layer of chromium metal 0.28 mm thick on an auto bumper wi...