问题 计算题

在由铜片、锌片和200 mL稀硫酸组成的原电池中,若锌片只发生电化学腐蚀,当在铜片上放出3.36 L(标准状况)的氢气时,硫酸恰好用完,则:

(1)产生这些气体消耗的锌的质 量是多少?

(2)通过导线的电子的物质的量是多少?

(3)原稀硫酸的物质的量浓度是多少?

答案

(1)9.75 g  (2)0.3 mol  (3)0.75 mol/L

题目分析:(1)氢气的物质的量是3.36L÷22.4L/mol=0.15mol

则根据反应的化学方程式可知

Zn  +  H2SO4=ZnSO4+H2

1mol     1mol        1mol

0.15mol  0.15mol     0.15mol

所以消耗锌的质量是0.15mol×65g/mol=9.75mol

(2)转移电子的物质的量是0.15mol×2=0.3mol

(3)原稀硫酸的浓度是0.15mol÷0.2L=0.75mol/L

点评:该题是基础性试题的考查,难度不大。主要是考查学生对原电池原理的了解、掌握程度,有利于培养学生的逻辑推理能力和规范答题能力,提高学生分析问题、解决问题的能力。

阅读理解

John Davis doesn’t use his GPS system in his car. Instead of guiding the direction, the Delaware farmer uses it to determine where and how much fertilizer to use on the crops on his 4,000-acre family-owned farm. Technological advances like that last year helped Davis and other Ohio farmers set a record for corn product. Ohio's corn crop in 2009 totaled 546 million bushels(蒲式耳), despite a cooler and wetter than normal spring, a dry summer and a delayed, wet harvest. Davis said. “I knew it would be a good crop, but it was much better than we expected.”

A farmer can map his fields on GPS, spotting where soil turned out to be least fertile(肥沃的) and using more fertilizer the next year in those areas where corn didn’t grow as well.

Although Ohio farmers produced more corn, it was grown on less land than in the past years. Total area used for corn in Ohio was 3.35 million acres, about the same as in 2008 but down from 3.85 million acres in 2007, said Dwayne Siekman, director of the Ohio Corn Growers Association. “When you look at the total number of acres in Ohio used for corn, it’s clear that farmers are able to do more with less,” he said. “American farmers can grow five times more corn on 20 percent less land than they did in the 1930s, saying that modern farming techniques are necessary for a growing demand in the world today.” That technology includes using improved seeds that can withstand(忍受) greater temperature extremes and pests, Siekman said.

Farmers aren't the only ones who benefit. Consumers(消费者) do, too, as food costs reduce in the face of “enough supplies of corn,” said Fred Yoder, who runs a 1,500-acre corn, soybean and wheat farm in Plain City. “This is the best, highest-producing corn crop that I've raised in 30 years,” he said.

小题1:Most people usually use the GPS system for ______.

A.driving their cars

B.telling the position

C.mending the car

D.supplying the sunshine小题2:The farmers in Ohio use GPS to ______.

A.check if the soil is fertile in some areas

B.control the rain of the place

C.water the crops if the weather is dry

D.draw the map of all the crops小题3:Why did Ohio farmers produce more corn?

A.Because they expanded more land to grow corn

B.Because they turned to technological advances

C.Because they used more and more fertilizer.

D.Because they supplies themselves with more money.小题4: From the passage, we can know _____.[

A.John Davis hadn’t expected a good harvest.

B.farmers grew less land than in the 1930s

C.improved seeds cost much more money

D.the output of corn in the same field is increased.

多项选择题