Some molecules may contain no atoms.
B.
Some elements found in nature exist as molecules.
C.
Some compounds include only one type of element.
D.
Some atoms are made of two or more different elements. Which of these statements is true?
A.
Some molecules may contain no atoms.
B.
Some elements found in nature exist as molecules.
C.
Some compounds include only one type of element.
D.
Some atoms are made of two or more different elements.
C2H5OH(l)+3O2(g)→2CO2(g)+3H2O(l), ΔH = –1367 kJ/mol
C(s)+O2(g)→CO2(g), ΔH = –393.5 kJ
H2(g)+½O2(g)→H2O(l), ΔH = –285.8 kJ
a. -277.6 kJ/mol
b. -194.7 kJ/mol
c. 194.7 kJ/mol
d. 486 kJ/mol
Answer:
The answer is a. -277.6 kJ/mol
Explanation:
We have to arrange and sum the given equations to obtain the desired reaction as follows:
3 H₂O(l) + 2 CO₂(g) → 3 O₂(g) + C₂H₅OH(l) ΔH1= (-1) x (-1367 KJ/mol)
2 C(s) + 2 O₂(g)→ 2 CO₂(g) ΔH2= 2 x (-393.5 KJ/mol)
3 H₂(g) + 3/2 O₂(g) → 3 H₂O(l) ΔH3= 3 x (-285.8 KJ/mol)
In the first equation (ΔH1) , we multiply the enthalphy by (-1) because we use the reverse reaction. In the second and third equations (ΔH2 and ΔH3), we multiply by 2 and 3, respectively. Once we sum and cancel the terms that are repeated in both sides of the reactions, we obtain:
3H₂(g) + 2C(s) + ½O₂(g) → C₂H₅OH(l)
The total enthalphy is:
ΔH= ΔH1 + ΔH2 + ΔH3
ΔH= (-1) x (-1367 KJ/mol) + 2 x (-393.5 KJ/mol) + 3 x (-285.8 KJ/mol)
ΔH= -277.4 KJ/mol
The nearest answer between the given options is option a (-277.6 KJ/mol)