Concerning the reaction how many grams of C(graphite)must be burned to release 275 kJ of heat?
A)0.70 g
B)8.40 g
C)12.0 g
D)17.1 g
E)22.3 g

Question

Concerning the reaction  how many grams of C(graphite)must be burned to release 275 kJ of heat?
A)0.70 g 
B)8.40 g 
C)12.0 g 
D)17.1 g 
E)22.3 g

Quizplus · Accepted Answer

First, we need to write the balanced chemical equation for the combustion of graphite:
C(graphite) + O2(g) → CO2(g)

From the equation, we can see that 1 mole of C(graphite) reacts with 1 mole of O2 to produce 1 mole of CO2 and release 393.5 kJ of heat.

So, the amount of heat released by burning x grams of C(graphite) can be calculated as follows:
275 kJ = (x g C)(1 mol C/ 12.01 g C)(393.5 kJ/mol)
Solving for x, we get:
x = (275 kJ)(12.01 g C/393.5 kJ) ≈ 8.40 g C

Therefore, the answer is B, 8.40 g.

Concerning the Reaction How Many Grams of C(graphite)must Be