Iron supplement tablets containing iron(II) sulfate can be used in chemistry demonstrations as a convenient, household source of small quantities of iron(II) ions. When the tablet is burned in air, oxygen converts the iron(II) in the tablet ultimately to iron(III) oxide in the hematite phase. Heating pure iron(II) sulfate heptahydrate also produces hematite. However, for the tablet, and for mixtures of iron(II) sulfate heptahydrate and starch, other iron oxide species such as magnetite and maghemite are produced before complete conversion to hematite. The presence of the starch, and cellulose in the tablets, appears to slow the oxidation of the iron(II). Magnetite and maghemite can be captured, observed by X-ray diffraction, and are much more strongly attracted to a magnet than hematite. The changes in color and magnetic susceptibility during iron supplement tablet combustion enable it to be used as an interesting demonstration of oxidation.

中文翻译：

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补充铁片燃烧引起的磁性和氧化作用的演示

含有硫酸铁（II）的铁补充剂片剂可在化学演示中用作方便的家用少量铁（II）离子源。当片剂在空气中燃烧时，氧气将片剂中的铁（II）最终转化为赤铁矿相中的氧化铁（III）。加热纯七水合硫酸铁也可生成赤铁矿。但是，对于片剂以及七水合硫酸铁（II）和淀粉的混合物，在完全转化为赤铁矿之前会生产其他氧化铁物种，例如磁铁矿和磁赤铁矿。片剂中淀粉和纤维素的存在似乎减慢了铁（II）的氧化。磁铁矿和磁赤铁矿可以被捕获，通过X射线衍射观察到，并且比赤铁矿更强地被磁铁吸引。