论文部分内容阅读
笔者批阅《 2000年全国初中生化学素质和实验能力竞赛试题》时，发现 29题的原标准答案有误，后翻阅了 100多份试卷，有 50％以上的试卷中都出现了与原标准答案类似的错误。 29题是： 20克 CuO溶于 140克温热的 20％ H2SO4溶液，冷却到 20℃时能从溶液中析出多少克 CuSO4· 5H
When the author reviewed the “National Junior High School Students’ Chemistry Quality and Experimental Ability Contest Questions” in 2000, he found that the original standard answers to the 29 questions were incorrect. After reading more than 100 papers, more than 50% of the papers appeared with the original standard answers. Similar mistakes. Question 29 is: How many grams of CuSO4· 5H can be precipitated from solution when 20 g CuO is dissolved in 140 g of warm 20% H2SO4 solution and cooled to 20°C?