题干

某中学化学课外活动小组对某工厂排放的含少量硫酸的废水进行抽样检测.取一定量的废水,用质量分数为1%的氢氧化钡溶液中和(其它物质不与氢氧化钡反应),当恰好中和时,消耗氢氧化钡溶液的质量为171g,过滤后,测得滤液的质量为268.67g.(不考虑过滤时滤液质量损失)(计算结果保留二位小数)

求:①反应中生成沉淀的质量为多少?

②该工厂排放的废水中所含硫酸的质量分数为多少?

上一题 下一题 0.0难度 选择题 更新时间:2019-04-24 09:19:47

答案(点此获取答案解析)

解:①设生成沉淀的质量为x

H2SO4+Ba(OH)2═BaSO4↓+2H2O

98    171   233

y   171g×1%  x

171233

同类题4

阅读理解

    Tom Costello was once afraid of homeless Americans. “I was so afraid that if I saw a homeless person walking down the street, I'd cross the street,” he said.

    That changed seven years ago after his wife, Nancy, a volunteer at a homeless shelter, persuaded him to help with a holiday dinner for shelter residents. Tom remembered going to a store and buying socks for the residents. He knew many of them were in need of clothing.

    At the shelter, Tom said, he dropped a pair of socks into a bag for a woman. She asked him if she could have socks for a friend who wasn't with her that day. He gave her another pair. “She started to cry and told me that nobody had ever given her socks before,” Tom said, “Then she reached out and gave me a hug.” That experience at the shelter helped Tom end his fear of the homeless.

    It also led him to set up a group called “The Joy of Sox.”, which borrows from a name of a popular book. The group collects socks from donors and gives them mostly to shelters in the area where Tom and Nancy live. It has been expanding its reach and provides socks to homeless shelters in 21 states and other three countries now.

    Why socks? Tom explains that some Americans give food, coats and other clothing to shelters. But donating socks is not something most people think about. And, he said, socks are very helpful at keeping people warm, especially in cold weather. A man named Kiwi,who has lived in homeless shelters, said most of the time he could find enough food through shelters and soup kitchens. But socks were much more difficult to get, he noted.