CHM-13

Heat capacity q = n Cp ΔT

q = n Cp ΔT at constant pressure.

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ThermochemistryCalorimetry

Governing equation

q=n C_p\Delta T

where

n: Amount (mol)
C_p: Molar heat capacity (J/(mol·K))
\Delta T: Temperature rise (K)
q: Heat (kJ)

Lecture brief

Historical brief

Ideal-gas law, van ’t Hoff, Nernst, Michaelis–Menten and Clausius–Clapeyron are physical chemistry’s working equations of equilibrium and rate. The lab is pressure, potential and kinetics. This sheet (CHM-13 — Heat capacity q = n Cp ΔT) is the form associated with Calorimetry. Working symbols: $n$ , $C_p$ , $\Delta T$ $\rightarrow$ $q$ . Cp = (∂H/∂T)_p. For an ideal gas Cp − Cv = R.

Purpose

Purpose: compute

q

from

n

C_p

\Delta T

in Physical chemistry via

q=n C_p\Delta T

q = n Cp ΔT at constant pressure. Use it when a real physical chemistry question must be answered in SI before a code check.

Live realistic example

In symbols

Live case. Given

n = 2.000\,\mathrm{mol}

C_p = 75.000\,\mathrm{J/(mol·K)}

\Delta T = 10.000\,\mathrm{K}

, the governing relation

q=n C_p\Delta T

yields

q = 1.500\,\mathrm{kJ}

. Constant Cp, no phase change in the interval. Move a slider: the numbers are this situation, not a canned story.

Calculator

Inputs

Amount n2 molMolar heat capacity C_p75 J/(mol·K)Temperature rise \Delta T10 K

Outputs

Heat q1.500 kJ

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Narration of this film

Constant Cp, no phase change in the interval.

Cp = (∂H/∂T)_p. For an ideal gas Cp − Cv = R.

Reading speed

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