问题 问答题

部分被氧化的铁片10g与200g的稀硫酸恰好完全反应,产生氢气0.3g,求该硫酸溶液的溶质质量分数?

答案

设Fe的质量为x,消耗H2SO4的质量为y

Fe+H2SO4═FeSO4+H2

56  98          2

x   y          0.3g

∴56:2=x:0.3g,98:2=y:0.3g,

解得x=8.4g,y=14.7g,

那么混合物中氧化铁的质量=10g-8.4g=1.6g,

设1.6gFe2O3消耗硫酸的质量为z,

Fe2O3+3H2SO4═Fe2(SO43+3H2O

160    294

1.6     z

∴160:294=1.6g:z,

解得z=2.94g,

那么硫酸溶液中硫酸的总质量为:2.94+14.7=17.64g,

那么硫酸的质量分数=

17.64g
200g
×100%=8.82%.

答:该该硫酸溶液的溶质质量分数为8.82%.

单项选择题

If the opinion polls are to be believed, most Americans are coming to trust their government more than they used to. The habit has not yet spread widely among American Indians, who suspect an organization which has so often patronized them, lied to them and defrauded them. But the Indians may soon win a victory in a legal battle that epitomizes those abuses.

Elouise Cobell, a banker who also happens to be a member of the Blackfeet tribe in Montana, is the leading plaintiff in a massive class-action suit against the government. At issue is up to $10 billion in trust payments owed to some 500,000 Indians. The suit revolves around Individual Indian Money (11M) accounts that are administered by the Interior Department’s Bureau of Indian Affairs (BIA). Back in the 1880s, the government divided more than 11m acres of tribal land into parcels of 80 to 160 acres that were assigned to individual Indians. Because these parcels were rarely occupied by their new owners, the government assumed responsibility for managing them. As the Indians’ trustee, it leased the land out for grazing, logging, mining and oil drilling--but it was supposed to distribute the royalties to the Indian owners.

In fact, officials admit that royalties have been lost or stolen. Records were destroyed, and the government lost track of which Indians owned what land. The plaintiffs say that money is owing to 500,000 Indians, but even the government accepts a figure of about 300,000. For years, Cobell heard Indians complain of not getting payment from the government for the oil-drilling and ranching leases on their land. But nothing much got done. She returned to Washington and, after a brush-off from government lawyers, filed the suit.

Gale Norton, George Bush’s interior secretary was charged with contempt in November because her department had failed to fix the problem. In December, Judge Lam berth ordered the interior Department to shut down all its computers for ten weeks because trust-fund records were vulnerable to hackers. The system was partly restored last month and payments to some Indians, which had been interrupted l resumed.

And that is not the end of it. Ms Norton has proposed the creation of a new Bureau of Indian Trust Management, separate from the BIA. Indians are cross that she suggested this without consulting them. Some want the trust funds to be placed in receivership, under a , neutral supervisor. Others have called for Congress to establish an independent commission, including Indians, to draw up a plan for reforming the whole system. A messy injustice may at last be getting sorted out.

What is implied but not stated in the first sentence is that American Indians()

A. expressed their gratitude for their lawyers

B. won a victory by use of legal weapons

C. have lost confidence in their government

D. came to believe the public opinion polls

填空题