4. Identify the phase of each of theses models (solid, liquid or gas)
1 answer:
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Explanation:
The given data is as follows.
Thickness = 0.28 mm = cm = 0.028 cm
Area = 0.40 =
= 4000
As, it is known that volume = area × thickness
So, Volume =
= 112
As density is mass divided by volume. So, mass of chromium will be calculated as follows.
Density =
7.20 =
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 =
=
= 15.50 mol
In chromate ion, () charge on Cr is +6. It means that 6 electrons are needed to reduce
into Cr.
As, 1 mole of 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.
=
= electrons
There is magnitude of times the charge on an electron is equal to 1 coulomb.
Hence, number of coulombs will be as follows.
No. of coulombs =
= C
or, = C
Thus, we can conclude that C are required to plate a layer of chromium metal with given data.