题目

纳米TiO2在涂料、光催化、化妆品等领域有着极其广泛的应用。制备纳米TiO2的方法之一是TiCl4水解生成TiO2·xH2O，经过滤、水洗除去其中的Cl- ， 再烘干、焙烧除去水分得到固体TiO2。实验室用氧化还原滴定法测定TiO2的质量分数：一定条件下，将TiO2溶解并还原为Ti3+ ， 再以KSCN溶液作指示剂，用NH4Fe(SO4)2标准溶液滴定Ti3+至全部生成Ti4+。请回答下列问题： （1） TiCl4水解生成TiO2·xH2O的化学方程式为。 （2） 配制NH4Fe(SO4)2标准溶液时，加入一定量H2 阅读理解。 　　Eating in space is different from eating on the earth．The food that astronauts bring with them is not the same food they eat on the earth． 　　Some food is carried in closed bags．It is cooked and frozen before an astronaut goes into space．All the water is taken from the food．In the spaceship, the astronaut puts the water back．He“shoots”hot or cold water into the food bag with a special gun．He eats the food through a small hole in the bag． 　　Other food comes in bite-size．The astronaut puts a whole piece in his mouth quickly．There can be no crumbs(碎屑)．Crumbs would float around the capsule(太空舱)and get in the way．Meat, cakes and other kinds of food often come in bite-size pieces． 　　Astronauts cannot drink water from open cups．Water will fly in drops in the air．The water is kept in the special gun．The astronaut shoots the water into his mouth． 　　Eating and drinking in space is not easy．Astronauts must learn to eat and drink this way． (1) Some space food is carried in ________． [　　] A． water guns B． lunch boxes C． closed bags D． baskets (2) The main idea of the text is ________． [　　] A． there is more food and water in space than on the earth B． eating and drinking in space is quite different and difficult C． astronauts can never eat or drink in a spaceship D． water is not easy to carry in a spaceship