Mixture (source code)
= Mixture
{wiki}
A <mixture> contains two or more <chemical substances> combined in proportions that need not be fixed. A <chemical compound> instead has a definite composition: <water> has two <hydrogen> <chemical atoms> per <oxygen> <chemical atom>, whereas a <sucrose> and <water> <mixture> can contain different sugar proportions. A homogeneous <mixture> has uniform composition on the scale of representative samples; a heterogeneous <mixture> has distinguishable regions of different composition. A <chemical solution> is homogeneous, whereas sand dispersed in <water> is a <particle suspension>.<Chemistry 2e by Paul Flowers and others/1.2 Phases and Classification of Matter>[Chemistry 2e, §1.2, Classification of Matter: mixtures, variable composition, homogeneous and heterogeneous examples]{ref}
The distinction concerns the sample, not merely its ingredient list. A vessel with dissolved <sodium chloride> and excess undissolved <sodium chloride> contains a <chemical solution> and an <ionic crystal> <thermodynamic phase>. The <liquid> portion can be homogeneous while the whole vessel is heterogeneous. Similarly, <molecular oxygen> dissolved in <water> is part of a <chemical solution>; visible <gas> bubbles introduce a separate <gas> <thermodynamic phase>.
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