Chemistry · Chapter 16

Slide ΔH, ΔS and T

Move the three sliders and watch the sign of ΔG flip. The crossing point is always T = ΔH°/ΔS°, and the panel keeps the units straight for you.

ΔG against temperature 

The tug of warΔH against TΔS

ΔG is what is left after TΔS is taken away from ΔH. Only the TΔS bar grows with temperature, so it is the one that can change the result.

Live numbersΔG = ΔH − TΔS

 kJ  ΔG spontaneous
ΔH 
ΔS, as listed 
ΔS, converted 
T 
TΔS 
crossover T 

Sliders

Real reactions

The four cases
Watch the slope
The slope of the line is minus ΔS. A positive ΔS tilts the line down, so heating helps. A negative ΔS tilts it up, so heating hurts.