How much heat is absorbed when 30.00 g of C(s) reacts in the presence of excess SO₂(g) to produce CS₂(l) and CO(g) according to the following chemical equation?
5 C(s) + 2 SO₂(g) → CS₂(l) + 4 CO(g) ΔH° = +239.9 kJ

Question

Quizplus · Accepted Answer

The given chemical equation is: 
5 C(s) + 2 SO2(g) → CS2(l) + 4 CO(g)
ΔH° = +239.9 kJ (positive, indicating the reaction is endothermic)

We are given the amount of carbon (C) as 30.00 g. To use this value, we need to convert it to moles of C.

Molar mass of C = 12.01 g/mol

Number of moles of C = mass of C / molar mass of C
                     = 30.00 g / 12.01 g/mol
                     = 2.4988 mol (rounded to 4 significant figures)

From the balanced chemical equation:
5 moles of C reacts to produce 4 moles of CO
Therefore, the moles of CO produced in the reaction = (4/5) x 2.4988 = 1.999 moles (rounded to 3 significant figures)

Now, let's use the given ΔH° value to calculate the amount of heat absorbed in the reaction:

ΔH = q/n
where, 
q = amount of heat absorbed (in kJ)
n = number of moles of C reacted

ΔH = (+239.9 kJ) / 2.4988 mol 
    = 96.03 kJ/mol

Multiplying this value by the number of moles of C reacted (2.4988 mol, rounded to 4 significant figures), we get: 
Amount of heat absorbed = ΔH x n
                       = 96.03 kJ/mol x 2.4988 mol
                       = 239.7 kJ (rounded to 3 significant figures)

Therefore, the answer is A) 119.9 kJ (half of 239.7 kJ) as the question asks for the amount of heat absorbed only for the given amount of carbon (30.00 g).

How Much Heat Is Absorbed When 30