问题 填空题

(8分)在牙膏中,常用轻质碳酸钙粉末做摩擦剂。人们通常用下列方法生产轻质碳酸钙:(1)将石灰石煅烧制得氧化钙,化学方程式是                               

(2)再将氧化钙加水制成氢氧化钙,化学方程式是                               ,该反应属于                      ;(填反应类型)

(3)然后将净化后的氢氧化钙与二氧化碳反应得到轻质碳酸钙,化学方程式是:

                                           

张佳蕾同学对上述生产过程产生怀疑,石灰石的主要成分是碳酸钙,轻质碳酸钙的成分也是碳酸钙,为什么还要花人力、物力和时间去转化一番?请你帮张佳蕾同学解开这个结:                        

答案

(1)CaCO3CaO  +   CO2

(2)CaO + H2O = Ca(OH)2  ;化合反应

(3)Ca(OH)2  + CO2 =CaCO3↓+H2O

石灰石的杂质含量较高,影响牙膏的品质,而转化后的轻质碳酸钙比较纯净,适宜卫生要求。(只要表述出石灰石中含有杂质就可以。表述合理即可)

题目分析:根据具体反应判断出反应物和生成物,并依据质量守恒定律书写化学方程式。

(1)碳酸钙高温分解生成氧化钙和二氧化碳,故化学方程式是CaCO3CaO + CO2↑;

(2)氧化钙能与水反应生成氢氧化钙,故化学方程式是CaO + H2O = Ca(OH)2,该反应是两种物质反应生成一种物质的化学反应,符合化合反应的特征,故属于化合反应;

(3)氢氧化钙与二氧化碳反应生成碳酸钙和水,故化学方程式是Ca(OH)2+CO2=CaCO3↓+H2O;

由于石灰石中含有的杂质含量较高,直接用于牙膏会影响牙膏的品质,而转化后的轻质碳酸钙比较纯净,适宜卫生要求,故需要转化。

点评:理解和熟练掌握碳酸钙、氧化钙和氢氧化钙的相互转化,及其化学方程式的书写,是解答此题的关键。

单项选择题
单项选择题

(C)

Ocean Park Hong Kong is a theme park in the Southern District of Hong Kong Island. The park was built with donations from the Royal Hong Kong Jockey Club (now Hong Kong Jockey Club) and opened on 10 January 1977. The park is operated by Ocean Park Corporation, which is a statutory department. It offers affordable marine animal education and entertainment and is a private organization for commercial purposes.

In the early operation of the park, the main sources of income for the park were the ticket prices and the funding from the Jockey Club. Since the ticket price was low, most of the time Ocean Park was operating under deficit. In 1 July 1987, the government established a 200 million trust from the funding of Jockey Club, under the Ocean Park Corporation Ordinance. This separated Ocean Park from Jockey Club and became a non-profit organization; it needs to be responsible for its own income and was allowed to use commercial meansto operate the park.

Since it was permitted to use commercial means to operate, it gradually raised its ticket price and the deficit turned into profit. In 1992, 3 million visitors visited the park. Since 1998, the East Asian financial crisis, aging attractions, and the passing away of the killer whale; the park recorded a deficit for a couple years. Although it was allowed to host 2 pandas in 1999, the number of visitors did not go up and Ocean Park was forced to close its water attractions and the "Old Village" attraction and turned to bring in more rides in an attempt to capture the youth demand. Together with the opening up of mainland visitors under the Individual Visit Scheme, Ocean Park recorded an astonishing 4 million visitors in the year 2004-2005, the highest since the park opened.

In March 2005, Ocean Park made its redevelopment plan. On 23 November 2006, Ocean Park held a groundbreaking ceremony for its redevelopment.

Ocean Park Corporation took all of the measures to overcome the deficits except ()。

A. raise ticket price

B. close some attractions

C. try to attract young customers

D. host 2 pandas