Abstract Mass fraction and dosage of soapy water, hardness of water and temperature and other factors will affect the experimental results of “using soapy water to distinguish soft water from hard water”. At room temperature, soapy water meets hard water to form scum or disperse scum. When the temperature is too high, soapy water will not generate scum when it meets hard water, but it will produce foam. Soapy water can not only compare the hardness of different water in daily life, but also soften hard water.
QI Zhi-He, LI Qing-Hua, LUO Xiu-Qun. Experimental Inquiry on Differentiating Soft and Hard Water by Soapy Water[J]. Chinese Journal of Chemical Education, 2020, 41(9): 87-91.
