题干

生活中有不少女性喜欢使用粉搽脸,若长期使用劣质香粉,脸上容易出现一些斑点,这是因为其中含有的铅白[2PbCO3•Pb(OH)2]与皮肤中的硫化物作用产生黑色硫化铅.除去这种黑色斑点的主要方法是选用合适的氧化剂将其氧化为难溶于水和酸的白色化合物,供选择的氧化剂有:①漂白粉、②高锰酸钾(氧化性强,还原产物在酸性较强的环境中为Mn,在中性或弱酸性环境中为MnO2)、③H2O2(还原产物为H2O).试回答下列问题:

(1)应选用何种氧化剂去掉PbS:____ ,理由是____ 

(2)写出除去PbS时可能发生反应的化学方程式____ 

上一题 下一题 0.0难度 选择题 更新时间:2019-02-07 05:38:00

答案(点此获取答案解析)

H2O2,PbS被氧化成PbSO4,不会留下难以消除的物质,PbS+4H2O2=PbSO4+4H2O

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    Having three cancer patients in the same household can turn a whole family upside down. Michelle Bruce, her husband, Jeremy, and their son, Holden, all had cancer. The family moved to Michelle's hometown of Franklin, Nebraska six years ago, so her parents could help.

    Doctors found Holden's brain tumor(肿瘤), when he was 12 years old. His family was living in a small town at the time, but there were related doctors in the state. Holden had two operations in Omaha clinic, both of which were tough.

    When Holden's cancer came back again in 2012, nothing could be done. But the family didn't give up. They reached out to Boston Children's Hospital, which has better equipment and doctors with more experience operating on kids. After looking at Holden's records, the doctor sent back her diagnosis: She was confident that she could remove the tumor.

    The family was beyond relieved, until they learned insurance wouldn't cover any of the operation's costs. The operation would cost $39,000 – more than the parents could afford. The family got desperate.

    In a town of just 1,000 people, however, word traveled fast. Within days, a local woman Michelle had never met in person called to say she was planning an event to raise money for Holden. Michelle was touched.

    The event was uplifting. Finally, the town raised $45,000 – enough to cover not just Holden's hospital bills, but for Michelle and Jeremy's trip to Boston with their son. “I just didn't know what to say,” said Michelle. “Nobody could really believe it.”

    Holden's operation went much more smoothly than the first two. He is cancer-free and now is attending Central Community College-Hastings on a full-ride scholarship.