# Entropy Variation - System, Neighborhood and Universe

1. Mar 18, 2013

### jaumzaum

I learned ΔSuniv = ΔSsys + ΔSneib

If ΔSuniv > 0 the process is spontaneous.

But ΔS = Q/T right? Shouldn't Qsys = -Qneib? (The heat released by the system = - heat released by the neighborhood)
I cannot understand why this is wrong!

If it were the case, ΔSuniv would be always zero

Can anyone help me?

[]`s
John

2. Mar 18, 2013

### DrDu

$\Delta S=Q/T$ only for reversible processes.For irreversible processes, $\Delta S>Q/T$.