问题 填空题

许多化学反应在生产生活中有重要应用.

(1)用X射线检查肠胃疾病时,要让患者服用“钡餐”(主要成分是硫酸钡,硫酸钡难溶于水和盐酸).硫酸钡属于______(填“酸”、“碱”或“盐”),它是由钡离子和______(填离子符号)构成,碳酸钡(BaCO3)也难溶于水,但不能用碳酸钡制“钡餐”,这是因为碳酸钡与胃酸反应生成的BaCl2易溶于水,会使人中毒.若误服碳酸钡,可服用硫酸镁(MgSO4)使其与BaCl2反应进行解毒,该反应的化学方程式为______.

(2)实验室可用石灰水和纯碱反应来制取少量的烧碱,其化学方程式为______.

答案

(1)根据盐是由金属离子和酸根离子组成的化合物,故硫酸钡属于盐,它是由钡离子和硫酸根离子组成的化合物;硫酸镁(MgSO4)与BaCl2反应的化学方程式是BaCl2+MgSO4═MgCl2+BaSO4↓;

故答案为:盐;SO42-;BaCl2+MgSO4═MgCl2+BaSO4↓;

(2)氢氧化钙和碳酸钠反应生成氢氧化钠和碳酸钙,反应的化学方程式为Ca(OH)2+Na2CO3=2NaOH+CaCO3↓;

故答案为:Ca(OH)2+Na2CO3=2NaOH+CaCO3↓.

问答题

Dongfang Import & Export Co (Dongfang Co) and Lidar Steel Company (Steel Co) entered into a cooperation contract. According to the contract Dongfang Co was responsible for the importation of 10,000 metric ton (M/T) of iron ore and exportation of pig iron 6,000 M/T, while Steel Co was responsible for the processing of iron ore into pig iron; Steel Co was also under the obligation to complete the processing within 10 days upon the arrival of iron ore and then carry the pig iron to Tianjin port for export by Dongfang Co.On 10 March 2008 the first shipment of 5,000 M/T iron ore arrived at the designated port and was promptly carried to the premises of Steel Co for processing.10 days later the second shipment of 5,000 M/T arrived at the Chinese port. However Dongfang Co found that several bank accounts of Steel Co were frozen by the order of the court in a dispute with a third party. Therefore, it immediately despatched a written memo to Steel Co, stating that it would detain the second shipment of iron ore until Steel Co delivered the processed pig iron.Upon the receipt of the notice, Steel Co sent back a fax to express its sincere regret for its delay to deliver pig iron. Steel Co emphasised, however, that it suffered from insufficient funds to buy coke for the processing. It promised to make efforts to deal with this problem, but failed to specify any concrete measures to be taken or give the necessary security for the performance of the contractual obligation. Steel Co also urged that Dongfang Co deliver the remaining 5,000 M/T of iron ore.Considering the date for the shipment of pig iron was approaching but Steel Co did not deliver any processed pig iron, Dongfang Co declared the dissolution of the cooperation contract and sold the remaining 5,000 M/T of iron ore to a third party. Under such circumstances Steel Co brought an action against Dongfang Co for damages on the ground that Dongfang refused to deliver the second shipment of 5,000 M/T iron ore for processing.Required:Answer the following questions in accordance with the relevant provisions of the Contract Law of China, and give your reasons for your answer:

(b) State whether Dongfang Co was entitled to dissolve the cooperation contract and sell the remaining iron ore to a third party; and (3 marks)

单项选择题