问题 问答题

氨基磺酸(H2NSO3H)是一元固体强酸,溶于水和液氨,不溶于乙醇.在工业上用作酸性清洗剂、阻燃剂、磺化剂.用尿素[CO(NH22]和发烟硫酸(溶有SO3的硫酸)为原料合成氨基磺酸的路线如下:

(1)重结晶用10%~12%的硫酸作溶剂而不用水作溶剂的原因是______.

(2)“磺化”步骤中所发生的反应为:

①CO(NH22(s)+SO3(g)⇌H2NCONHSO3H(s)△H<0

②H2NCONHSO3H+H2SO4⇌2H2NSO3H+CO2

“磺化“过程应控制反应温度75~80℃,若温度高于80℃,氨基磺酸的产率会降低,原因是______.

(3)测定产品中氨基磺酸纯度的方法如下:称取7.920g产品配成l000mL待测液,量取25.00mL待测液于锥形瓶中,加入2mL 0.2mol•L-1稀盐酸,用淀粉碘化钾试剂作指示剂,逐滴加入0.080mol•L-1NaNO2溶液,当溶液恰好变蓝时,消耗NaNO2溶液25.00mL,此时氨基磺酸恰好被完全氧化成N2,NaNO2的还原产物也为N2

①写出氨基磺酸与NaNO2溶液反应的化学方程式______.

②产品中氨基磺酸的质量分数为______.

(4)以酚酞为指示剂,用NaOH进行酸碱中和滴定也能测定产品中氨基磺酸的纯度,测定结果通常比NaNO2法偏高,原因是氨基磺酸中混有______杂质.

答案

(1)反应H2NCONHSO3H+H2SO4⇌2H2NSO3H+CO2↑是可逆反应,硫酸浓度增大,平衡向正反应方向移动,所以能抑制氨基磺酸的溶解,

故答案为:氨基磺酸在硫酸溶液中的溶解度比在水中的溶解度小;

(2)温度越高,三氧化硫气体逸出速率加快,且CO(NH22(s)+SO3(g)⇌H2NCONHSO3H(s)是放热反应,升高温度,平衡向逆反应方向移动,从而抑制氨基磺酸的产率,

故答案为:温度高,SO3气体逸出加快,使反应①转化率降低.温度高,反应①平衡向逆反应方向移动;

(3)①氨基磺酸与NaNO2溶液反应的化学方程式:H2NSO3H+NaNO2=NaHSO4+N2↑+H2O,故答案为:H2NSO3H+NaNO2=NaHSO4+N2↑+H2O;

②当溶液变蓝色时,说明H2NSO3H恰好完全反应,氨基磺酸和亚硝酸钠的反应方程式为:H2NSO3H+NaNO2=NaHSO4+N2↑+H2O,

根据方程式知,n (H2NSO3H)=n(NaNO2)=25.00×l0-3×0.08000 mol•L-1=2.000×l0-3 mol,

ω(H2NSO3H)=

2.000×10-3mol×97g/mol
7.920g×
25ml
1000ml
×100%=98.0%,

故答案为:98.0%;

(4)用氢氧化钠测定氨基磺酸的纯度,测定结果通常比NaNO2法偏高,说明还有其它物质和氢氧化钠反应,能和氢氧化钠反应的物质是硫酸,故答案为:硫酸.

单项选择题

"I was just like you--I’ thought I was invincible," says Adam Blomberg, standing before 400 students in a darkened auditorium at Miami’s Coral Reef Senior High School. A photo of a bloodied and unconscious teenager, a breathing tube protruding from his mouth, flashes on the wall.

"That was me," he says. There’s a collective gasp before the room grows silent and Blomberg,31, an anesthesiologist who trained at Brigham and Women’s Hospital in Boston, begins the story of what happened one night in February 1995.

He created a presentation illustrating the dangers of behaving irresponsibly in a car, from not buckling up to speeding to driving under the influence of alcohol and drugs. He tracked down photos of teen crash victims from the center’s archives, then incorporated statistics and his own experience. He spoke the first time to a local Boy Scout troop and was soon giving his talk, "A Survivor’s Story," at high schools around the state.

The Blomberg family had reason to celebrate. Adam had fully recovered and was on his way to fulfilling his lifelong dream of becoming a doctor. But in January 2000, Blomberg’s 22-year-old step-brother, Michael, was killed in a crash while driving to his Atlanta home late one night. He wasn’t wearing a seat belt. After the accident, Blomberg stopped telling his story to crowds, racked with guilt over his inability to reach Michael. If Blomberg had failed his own brother, he reasoned, how could he possibly make a difference to a roomful of strangers Requests from schools continued to roll in, but he turned down every one.

Then Blomberg got a call from a high school counselor. As he started into his standard excuse-lack of time—he looked across the room at a stack of thank-you notes from students who had heard him speak. He realized that kids needed to hear what he had to say. He agreed to visit the school and began contacting others on the waiting list for his talks.

Blomberg leaves the school hoping he has changed someone’s behavior. He recalls a letter he received from a student who heard him speak and got into a crash later that same day but was unharmed. " She told me she was wearing her seat belt because of me."

Letters like this reinforce his belief that he survived the accident for a reason. "There are a lot of physicians in the world, and we all save lives," he says. "I have a special opportunity to save lives not just as a doctor but also as a human being.\

Why did the author stop giving speeches for a while()

A. The death of his stepbrother makes him feel guilty

B. The development of seat belt avoided most accidents

C. There are no more requests from schools inviting him

D. He did not have enough time to give lectures at that time

选择题