超一流化学高手、化学专家请进(Periodicity0039)请用英文解答(该题是要用英文解的答化学题,不是翻译题).Chromiumisametalthatisfoundinthewastewaterofsomefactoriesasdichromate(VI)ions.Ithastoberemoved

Question

超一流化学高手、化学专家请进(Periodicity 0039)
请用英文解答(该题是要用英文解的答化学题,不是翻译题).
Chromium is a metal that is found in the waste water of some factories as dichromate(VI) ions.It has to be removed from the waste water by converting the dichromate(VI) ions to chromium(III) ions,which are then precipated by forming the hydroxide.
(a) Explain why chromium must be removed.
(b) Suggest a way to form the hydroxide.
(c) State the formula of two compounds that are formed in the
method suggested above.
Thanks.
这是考大学生的题，并且要用英文解答，一般的大学化学讲师、教授也无法完全用英文回答。
不需要介绍网站。这里是交流园地，也是习作园地。代课教师的解答更不需要。

Answer 1

chromium is one of the heavy metal .It may harm human's health when people take the creature which absorb it as nutrition.ALso a heavy metal ion may cause the fish in the water die.All in a word it was harmful so factory must remove it before the waste water is emissioned.
use a CaO to adjust the PH of the water.Cr may be precipated at the pH of 6
Cr2O72-+14H++6e===2Cr3++7H2O
In factory we may use such electronating agent like FeSO4,SO32- to act as the e-
I was too tired to continue the answer last night.But I like these kind of questions which needs us to answer in English.I am Junior .though I have past the cet6 but my spoken english is very poor.I cant express what I want to tell clearly especially when it comes to my major english.I need excises.And thank you for providing such a good stage for me and other students with similiar thoughts.