Grade 12 Chemistry Energy

Jan 2020
2
0
Toronto
Coal is a majorenergy source forelectricity, of which industry is the largest user (Figure 3). Anthracite coal is a high-molar-mass carbon compound with a composition of about 95% carbon by mass. A typical simplest-ratio formula foranthracite coal is C52H16O(s). The standard enthalpy of formation of anthracite can be estimated at -396.4 kJ/mol. What is the quantity of energy available from burning 100.0 kg of anthracite coal in a thermal electric powerplant, according to the following equation?

2C52H16O(s) + 111O2(g) → 104 CO2(g) + 16 H2O(g)

So I started by dividing the equation by 2 and then used standard enthalpy of formation to calculate for delta H. I got -22000 KJ.

Not sure what to do next. The final answer is 3.34 x 10 to the power of 3 MJ.
Thanks!
 
Last edited:
Apr 2015
35
8
The standard enthalpy of formation of anthracite can be estimated at -396.4 kJ/mol. What is the quantity of energy available from burning 100.0 kg of anthracite coal in a thermal electric powerplant, according to the following equation?

2C52H16O(s) + 111O2(g) → 104 CO2(g) + 16 H2O(g)

So I started by dividing the equation by 2 and then used standard enthalpy of formation to calculate for delta H. I got -22000 KJ.

Not sure what to do next. The final answer is 3.34 x 10 to the power of 3 MJ.
Thanks!
Surely the first thing to do is to convert 100kg to moles!
Is the 95% factor relevent?
 
Jan 2020
2
0
Toronto
No, the 95% is not relevant

I calculated for the moles of 100 kg of anthracite coal to be 152.44 mols
and then,

152.44 mols x -22000 KJ/mol
= -3353680 KJ
= - 3353 MJ = -3.35 x 10 to the exponent 3 MJ

Is this right?
 
Last edited:
Apr 2015
35
8
Well I haven't checked the arithmetic but the bottom line matches.