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Chemistry: Post your doubts here!

Messages
70
Reaction score
10
Points
18
Skiers trapped by snowstorms use heat packs to keep warm. The heat may be generated by the
reaction below.
4Fe(s) + 3O2(g) → 2Fe2O3(s) ; ∆HO = –1648kJ
What is the standard enthalpy change of formation of iron(III) oxide?

A 0kJmol–1
B –824kJmol–1
C –1648kJmol–1
D –3296kJmol–1

helppppppppppppppppppppppppp!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
 
Messages
191
Reaction score
80
Points
38
Skiers trapped by snowstorms use heat packs to keep warm. The heat may be generated by the
reaction below.
4Fe(s) + 3O2(g) → 2Fe2O3(s) ; ∆HO = –1648kJ
What is the standard enthalpy change of formation of iron(III) oxide?

A 0kJmol–1
B –824kJmol–1
C –1648kJmol–1
D –3296kJmol–1

helppppppppppppppppppppppppp!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!
since the enthalpy change of formation of 2 moles of iron(III) oxide is -1648 the standard enthalpy change of formation of 1 mole of iron(III) oxide will be the half which is B
 
Messages
108
Reaction score
37
Points
38
Oxidation no. of N is -3.
Oxidation no. of H is +1.
Oxidation no. of O is -2.
Sum of oxidation no.s in a compound must equal zero.

When you calculate it, C is the only option.

Because, look:

NH4ClO4 -> -3+4+x-8=0
-> 1+x-8=0
-> -7+x=0
->x=7
oh my gosh,you explained it so well! Thankyou!!!!
 
Messages
103
Reaction score
28
Points
28
Skiers trapped by snowstorms use heat packs to keep warm. The heat may be generated by the
reaction below.
4Fe(s) + 3O2(g) → 2Fe2O3(s) ; ∆HO = –1648kJ
What is the standard enthalpy change of formation of iron(III) oxide?

A 0kJmol–1
B –824kJmol–1
C –1648kJmol–1
D –3296kJmol–1

helppppppppppppppppppppppppp!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!

What on Earth is "∆HO"?
 
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