440 cause mass cant be created or destroyed
Answer:
412.1kJ
Explanation:
For the reaction , from the question -
4Fe (s) + 3O₂ (g) → 2Fe₂O₃ (s)
Δ Hrxn = Δ H°f (products) - Δ H°f (reactants)
In case the compound is in its standard state , enthalphy of formation is zero
Hence ,
for the above reaction ,
ΔHrxn =( 2 * Δ H° (Fe₂O₃ )) - [ ( 4 *Δ H° Fe ) + (3 * Δ H° O₂ )]
The value for Δ H°(Fe₂O₃ ) = - 824.2kJ/mol
Δ H° Fe = 0
Δ H° O₂ = 0
Putting in the above equation ,
ΔH rxn = ( 2 * Δ H° (Fe₂O₃ )) - 0
ΔHrxn = 2× - 824.2 kJ / mol = - 1648.4 kJ/mol
- 1648.4 kJ/mol , this much heat is released by the buring of 4 mol of Fe.
Hence ,
for 1 mol of Fe ,
- 1648.4 kJ/mol / 4 = 412.1kJ
That number has 6 significant numbers. It's precision would be 602.
Hope it helped.
Answer:
7.505
×
10
22
atoms. (rounded to third place of decimal)
Explanation:
There are four Hydrogen atoms in one molecule of Methane (CH₄).
And there are 6.022×10²³ molecules in 1 mole of CH₄.
So,
Number of Hydrogen atoms is 1 mole of CH₄ are,
= 6.022 × 10²³ × 4
= 2.4 ×10²⁴ Hydrogen Atoms
Now calculating for 2 moles,
As,
1 mole of CH₄ contains = 2.4 ×10²⁴ Hydrogen Atom
Then,
2 moles of CH₄ will contain = X Hydrogen Atoms
Solving for X,
X = (2 moles × 2.4 ×10²⁴ Hydrogen Atom) ÷ 1 mole
X = 4.8 × 10²⁴ Hydrogen Atoms
