Answer:
-608KJ/mol
Explanation:
3 C2H2(g) -> C6H6(g)
ΔHrxn = ΔHproduct - ΔHreactant
ΔHrxn= ΔHC6H6 - 3ΔHC2H2
ΔHrxn = 83 - 3(230)
ΔHrxn = -608
The answer is (2) 2 pairs. The oxygen atoms combine to get stable structure. So after the combination, each atom needs to have 8 electrons. So when they share 4 electrons can satisfy this requirement. Then there are 2 pairs shared.
The heat is involved in the production of 5.0 mol of MgO is 180 Kj
calculation
2 Mg (s) +O2 → 2 MgO
From the equation above two moles of MgO is used therefore
72.3 is for 2 moles
that is 72.3 kj = 2moles
? = 5 moles
by cross multiplication
= 72.3 kj × 5/2 = 180 Kj
Answer:
b. Mg (s) + 2HCl (aq) --> MgCl2 (aq) + H2
Explanation:
A subscript applies only to the element it is attached to while coefficients apply to all elements in a compound.
"a" has 1 atom of each element on the left but 2 Cl on the right.
"c" has 2 Mg, 1 H, & 1 Cl on the left but 1 Mg, 2 H, and 2 Cl on the right.
"d" has 2 atoms of each element on the left but only 1 Mg on the right.
"b" is the only answer with equal numbers of atoms on the right and left sides of the equation.
