Kev hais lus theoretical, cov tshuaj tiv thaiv ntawm cov kua qaub anhydride nrog dej yields cov kua qaub.
Lus Cim: Tsis yog tag nrho cov kua qaub anhydrides yuav hnov mob nrog dej los tsim cov kua qaub. Siv acetic anhydride, piv txwv li: nws yog tsim los ntawm * tshem tawm * ntawm dej ntawm acetic acid molecules. Txawm li cas los xij, cov dej tshem tawm no tsis tuaj yeem tsuas yog * rov txuas ntxiv * rau cov anhydride kom rov qab cov kua qaub qub.
Tib txoj cai siv rau SiO₂. H₄SiO₄ yog orthosilicic acid [Si(OH)₄], tsis yog silicic acid. Silicic acid yog H₂SiO₃; Yog li ntawd, cov khoom uas tshwm sim los ntawm kev tshem tawm cov dej yog SiO₂.
Cov anhydride ntawm H₄SiO₄ kuj yog SiO₂, vim H₄SiO₄ yog tshuaj sib npaug rau H₂SiO₃·H₂O. Cov dej molecules cuam tshuam tsuas yog "appended" rau cov qauv thiab tuaj yeem raug tshem tawm ncaj qha yam tsis muaj kev cuam tshuam rau cov tub ntxhais acid moiety. Qhov no yog qhov sib piv rau alum (KAl (SO₄)₂·12H₂O), qhov twg cov dej sib txuas ntawm crystallization tuaj yeem tsis pom zoo. Txawm hais tias cov dej molecules no tshwm sim hauv cov tshuaj formula, lawv ua haujlwm tsuas yog "sab nraud"-zoo li cov ris tsho hnav tshaj li cov qauv hauv qab.
