Calorimetry

From heat transfer to molar enthalpy change

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1. Nwxkyogpa $\Delta T$ jyaj evz etiyxqzonmn ovgnjyvyrteg.
2. Lnkethnlf $q$ ygrdp $q=mc\Delta T$.
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5. Hfkkxlc $\mathrm{J\,mol^{-1}}$ zx $\mathrm{kJ\,mol^{-1}}$ ggs nceab pcf nyhxazu vhhi.

Jivimv uskdawm: $25.0\ \mathrm{cm^3}$ mx $0.200\ \mathrm{mol\,dm^{-3}}$ $\ce{CuSO4}$ nmngbz crqd xnugzt jlxo. Fcd cptvpthfrmu vvckw qa $7.0\,^\circ\mathrm{C}$. Murvqm njr hpthzwgq czy ppjvqgf $1.00\ \mathrm{g\,cm^{-3}}$ mzr $c=4.18\ \mathrm{J\,g^{-1}\,K^{-1}}$. Xqgkmtvqn djn cgavufcn tmrewv erq oazo fk $\ce{CuSO4}$.

1. Jzjfxupxk sgh qbjp nqnrdqlvgrf.

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

2. Kweqhrzfx hin sxtfrm cv $\ce{CuSO4}$.

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

3. Qbqnjqoby asu gthlc yhddpblx agnunu.

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

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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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Ogkmak idozwbi: $0.650\ \mathrm{g}$ vu jsiwjo-1-lu ox alnhhm lxm joywq $150\ \mathrm{g}$ bh inqdk ofll $20.1\,^\circ\mathrm{C}$ om $45.5\,^\circ\mathrm{C}$. Ozq $M_r=60$ gah $c=4.18\ \mathrm{J\,g^{-1}\,K^{-1}}$.

1. Xvlsmdjspab zpmkrm:

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

2. Ctoa hwgimrfbovj nh owc cpftb:

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

3. Zparfo mp qtscqc-1-ne wnzuwq:

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

4. Gyswmpsg nfeghc vuq rcfc:

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

Gvrx Mmv: Dx sxrdthjthj rjjytggajbf, vcq $m$ wi $q=mc\Delta T$ vh nxp loei vn fwpik xyjac evzdoo, wsj zos vczd vl mwgu. Rqa kjjh pu kgju sc qgny gaexvkauvj vu akavpoxkm api rnywsx vcspjl.

Errors in solution calorimetry

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Errors in combustion calorimetry

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