One warmed sample, several possible responses — Physical Science: Chemistry

A rigid sealed gas vessel and a gas beneath a flexible boundary can respond differently to the same temperature increase. In the ideal model mean translational energy rises with absolute temperature, but the boundary determines whether pressure, volume or both change. Draw molecular motion without increasing molecule size, and identify the held quantities before choosing a gas law.

A ratio from 20°C to 40°C is not an absolute-temperature doubling: the temperatures are 293.15 and 313.15 K. A gauge reading also needs its atmospheric offset before use as absolute pressure. PV=nRT uses a compatible R and unit system; a molar-volume shortcut needs the stated pressure and temperature. Real gases can depart from ideal behavior near high density or phase changes.

For a sample changing phase, energy and thermometer response are separate accounts. Melting ten grams of ice at 0°C takes about 3340 J in the supplied ordinary-pressure model; warming the resulting water to 20°C adds 836 J. A plateau can absorb energy while phase fraction changes. A phase diagram organizes stable regions by pressure and temperature, with triple and critical points interpreted under the stated substance model.