题干

某学习小组探究铜跟浓硫酸反应的情况.取6.4g铜片和10mL 18mol•L﹣1的浓硫酸放在圆底烧瓶中,按右图所示装置进行实验.

(1)铜和浓硫酸反应的化学方程式为 ____ .

(2)实验结束后,发现广口瓶中产生白色沉淀,加入足量盐酸后沉淀几乎完全溶解.简要分析广口瓶中产生沉淀的主要原因:____ .

(3)实验结束后,发现烧瓶中有铜片剩余.根据所学知识,他们认为烧瓶中还有较多的硫酸剩余.选择合适的试剂,设计简单易行的实验方案证明有余酸:____ .供选择的试剂:铁粉、银粉、BaCl2溶液、Na2CO3溶液

(4)甲同学设计如下方案:测定产生气体的量,再计算余酸的浓度.下列测定产生气体的量的实验方法中,不可行的是____ (填编号).

a.将气体缓缓通过预先称量、盛有碱石灰的干燥管,反应结束后再次称量

b.将气体通入硫酸酸化的KMnO4溶液,再加足量BaCl2溶液,过滤、洗涤、干燥,称量沉淀

c.用排水法测定产生气体的体积

d.用排饱和NaHSO3的方法测定产生气体的体积

(5)乙同学设计通过酸碱中和滴定来测定余酸的浓度:待烧瓶冷却至室温后,将其中的溶液用蒸馏水稀释至100mL,移取25mL到锥形瓶中,滴加2滴酚酞试液,用标准NaOH溶液滴至终点.平行实验三次.

①稀释时,应先往____ (填仪器名称)中加入____ (填“烧瓶中的溶液”或“蒸馏水”).

②该方法测得的余酸浓度____ (填“偏大”、“偏小”或“准确”).

(6)丙设计了测定余酸浓度的较为简易的实验方案:取出反应后剩余的铜片,进行洗涤、干燥、称量.若称得剩余铜片的质量为3.2g,反应后溶液体积变化忽略不计,则剩余硫酸的物质的量浓度为____ .

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答案(点此获取答案解析)

Cu+2H2SO4\uff08\u6d53\uff09=\u25b3CuSO4+SO2\u2191+2H2O,\u70e7\u676f\u4e2d\u7684\u6eb6\u6db2

同类题5

阅读理解

    The spring season brings warm weather, flowers and other changes for people to enjoy. For some restaurant cooks, the most exciting spring arrival is ramps.

    Ramps are a wild plant in the eastern mountains of North America. They are one of the first plants that grow in the spring, usually between April and May. They are recognized(意识) by their red stem(茎), and two long and wide green leaves. They are also famous for their strong taste, similar to onions(洋葱).

    Ramps are not as well-known as other vegetables, but they have a long history in the United States. In the Appalachian Mountains, ramps have been an important food for a longtime. During spring, it is common for small towns in the Appalachian area to hold large ramp dinners for the community.

    However, over the last 30 years, ramps popularity has grown quickly. They are now a highly-desired vegetable for many nice restaurants in cities like New York and Washington D.C.

    One reason the plant is popular is that it grows in the wild. It is difficult to grow them on farms. Most restaurants get them from foragers, who collect ramps by searching forests for some small pieces of land where they grow. Ramps have a short season. Within a few weeks of full growth, the plant is done for the year. This shot life is some reason for their popularity.

    And that popularity could lead Io their disappearance from Earth. In 1995, the local government in Quebee, Canada, stopped people selling the plant to businesses in order to protect the plant against being over-dug.

    The season is short, but it has not ended yet. If you are in the right place, you still have time to try a taste of ramps yourself.

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