The empirical formula is Fe₃O₄.
The empirical formula is the <em>simplest whole-number ratio of atoms</em> in a compound.
The ratio of atoms is the same as the ratio of moles, so our job is to calculate the molar ratio of Fe to O.
I like to summarize the calculations in a table.
<u>Element</u> <u>Moles</u> <u>Ratio</u>¹ <u>×3</u>² <u>Integers</u>³
Fe 0.77 1 3 3
O 1.0 1.3 3.9 4
¹ To get the molar ratio, you divide each number of moles by the smallest number (0.77).
² If the ratio is not close to an integer, multiply by a number (in this case, 3) to get numbers that are close to integers.
³ Round off these numbers to integers (3 and 4).
The empirical formula is Fe₃O₄.

<h3>Further explanation</h3>
Given
3000 L of gas at 39°C and 99 kPa to 45.5 kPa and 16°C,
Required
the new volume
Solution
Combined with Boyle's law and Gay Lussac's law

T₁ = 39 + 273 = 312
T₂ = 16 + 273 = 289
Input the value :
V₂ = (P₁V₁.T₂)/(P₂.T₁)
V₂ = (99 x 3000 x 289)/(45.5 x 312)
or we can write it as:
V₂ = 3000 L x (289/312) x (99/45.5)
They are all transioning in states of matter
Answer:
As per the general rule for finding oxidation number, When H is bonded with non-metal it has oxidation number as 1. As in the given ion, hydrogen is bonded with non-metal oxygen and there are three hydrogen atom, the oxidation number of hydrogen atom is 3.
The energy in Joules is calculated as:
E = VQ
At standard conditions, the standard potential or the voltage is equal to 0.76 V. Next, we have to determine Q. The formula is as follows:
Q = nF, where n is the number of moles electron, while F is the Faraday's constant (96,500 C/mol e)
From the given reaction, notice that Zn was converted to Zn²⁺, while Cu²⁺ to Cu. So, 1 mol Cu = 2 mol e.
Q = 51 g Cu (1 mol Cu/63.55 g)(2 mol e/1 mol Cu)(96,500 C/mol e)
Q = 154885.92 C
Thus,
E = (0.76 V)(154885.92 C)
<em>E = 117,713.3 J</em>