Project ForgeThe equilibrium moisture (sorption isotherm) curve for a solid (relative humidity H vs. total moisture X) is given. A solid with total moisture X, exposed to air of relative humidity H, has: P. Equilibrium moisture, Q. Bound moisture, R. Unbound moisture, S. Free moisture, corresponding to regions: 1 (from 0 to the moisture in equilibrium with the actual air humidity H), 2 (from that point to X), 3 (from 0 to the moisture where the curve reaches 100% RH), 4 (from that point to X). Which ONE of the following is the correct match?
- AP-1, Q-2, R-3, S-4
- P-1, Q-3, R-4, S-2
- CP-1, Q-4, R-2, S-3
- DP-1, Q-2, R-4, S-3
Explanation
Equilibrium moisture (P) is, by definition, the moisture in equilibrium with the actual air humidity H — region 1. Bound moisture (Q) is the moisture held up to the point where the curve reaches 100% RH — region 3. Unbound moisture (R) is the excess beyond that bound-moisture limit — region 4. Free moisture (S) is the total moisture in excess of the equilibrium value at the ACTUAL humidity H (removable by drying under those conditions) — region 2.
Source: GATE CH 2009 (2009)
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