The method of identifying maleic anhydride and maleic acid was as follows

1、称取大约相同的量，用水溶解后，再用碱滴定，消耗碱多的是酐，消耗碱少的是酸。

1. Weigh about the same amount, dissolve it with water, and titrate with alkali. The more alkali consumed is anhydride, and the less alkali consumed is acid.

2、或取少量相同量的样品溶解于水，用pH计检测，pH值低的是酐，pH稍高的是酸。

2. Or take a small amount of the same amount of sample dissolved in water, detected by pH meter, the lower pH is anhydride, the higher pH is acid.
 

3、用熔点检测也可以，酐与酸的熔点不同。顺酐约52~53℃，顺酸约130℃。

3. The melting point of anhydride is different from that of acid. Maleic anhydride is about 52 ~ 53 ℃ and CIS acid is about 130 ℃.

4、简单的办法，找一小块不锈钢片，将两种样品各放一点于钢片两侧，用打火机在两个

4. A simple way is to find a small piece of stainless steel plate, put two kinds of samples on both sides of the steel plate, and use a lighter in two

样品中间加热，先液化并挥发的是顺酐。

When the sample is heated in the middle, maleic anhydride is liquefied and volatilized first.