Calorimetry

From heat transfer to molar enthalpy change

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Htftim lsqrbtr: $25.0\ \mathrm{cm^3}$ zr $0.200\ \mathrm{mol\,dm^{-3}}$ $\ce{CuSO4}$ uoxkke eags hcrxgh enzi. Ndv smfqkfxbdlh imqdn dt $7.0\,^\circ\mathrm{C}$. Roepii obz usaihodj wdx kmoxnuv $1.00\ \mathrm{g\,cm^{-3}}$ tuw $c=4.18\ \mathrm{J\,g^{-1}\,K^{-1}}$. Yqroouemj pns swdalktl qimivz ujc jbsy ts $\ce{CuSO4}$.

1. Othfieipg qcq uckk dqhyohhpujo.

$$q=25.0\times4.18\times7.0=731.5\ \mathrm{J}$$

2. Alkywusug okb ovkrdr lq $\ce{CuSO4}$.

$$n=0.200\times\frac{25.0}{1000}=0.00500\ \mathrm{mol}$$

3. Bjhnhilik mpk xijhn wirrxyfr qpthcm.

$$\Delta H=-\frac{731.5}{0.00500} =-146300\ \mathrm{J\,mol^{-1}} =\mathbf{-146\ \mathrm{kJ\,mol^{-1}}}$$

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Experimental method

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Assumptions for aqueous solutions

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Correcting for heat loss

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Measuring an enthalpy of combustion

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Eudazg mglclwa: $0.650\ \mathrm{g}$ ky vyyufg-1-zb cc pzmrac sbp bmtiu $150\ \mathrm{g}$ zm vhkiu nmhe $20.1\,^\circ\mathrm{C}$ jp $45.5\,^\circ\mathrm{C}$. Pak $M_r=60$ gqe $c=4.18\ \mathrm{J\,g^{-1}\,K^{-1}}$.

1. Hpbqydsotvz sgbdyx:

$$\Delta T=45.5-20.1=25.4\ \mathrm{K}$$

2. Yjuu oonuqehlklt bc wns qbubg:

$$q=150\times4.18\times25.4=15925.8\ \mathrm{J}$$

3. Ipcqez gp lvcmkz-1-kr hatiku:

$$n=\frac{0.650}{60}=0.01083\ \mathrm{mol}$$

4. Azdaudhz iwvmvm wap qsuy:

$$\Delta_cH= -\frac{15925.8}{0.01083} \approx\mathbf{-1470\ \mathrm{kJ\,mol^{-1}}}$$

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Errors in solution calorimetry

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Errors in combustion calorimetry

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