Answer:
ΔHrxn = [(1) -1675.5 ( kJ/mole) + (2) 0 ( kJ/mole)] - [(1) -824.3 ( kJ/mole) + (2) 0 ( kJ/mole)]
Explanation:
ΔHrxn = 2ΔHf (Al₂O₃) - ΔHf (Fe₂O₃)
Remember that for pure elements in their standard state of temperature and pressure by definition their standard heats of formation are zero.
ΔHrxn = 2(-1675.7) - (-824.3) kJ/mol
ΔHrxn = 2527 kJ/mol
Answer:
D
Explanation:
P4 is polyatomic molecule
We have to calculate the molar mass of AL(OH)₃
Atomic mass (Al)=27 amu
Atomic mass (O)=16 amu
Atomic mass (H)=1 amu
molecular weight= 27 amu+3(16 amu + 1 amu) =78 amu.
Therefore, the molar mass of Al (OH)₃ is 78 g/ mol
Now, we calculate the number of moles in 98.3 g of aluminum hydroxide.
78 g-------------------1 mol
98.3 g----------------- x
x=(98.3 g * 1 mol) / 78 g=1.26 moles.
Answer: 1.26 moles.
The awnser is A :)
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Answer:
Formation of a precipitate
Explanation:
- A precipitate is a compound in solid-state that is formed when two soluble or aqueous compounds or salts react during a precipitation reaction.
- Precipitation reaction involves a reaction between two soluble salts or compounds to form a precipitate and an aqueous compound.
- For instance, a reaction between potassium chloride and silver nitrate is a precipitation reaction.
KCl(aq) + AgNO₃(aq) → KNO₃(aq) + AgCl(s)
- All the other choices are indicators of a chemical reaction or a chemical change.