问题 问答题

在一些食品包装袋中放一些脱氧剂,可以除去袋中的氧气和水蒸气,从而使食品保质期延长.某校化学兴趣小组的同学为了探究脱氧剂的成分,打开小纸袋,将其倒在滤纸上,看到“脱氧剂”是灰黑色粉末,并混有少量的红色粉末.

[提出问题]该“脱氧剂”中的灰黑色、红色粉末各是什么?

[猜想]甲同学认为:灰黑色粉末为氧化铜、红色粉末为铜.

乙同学认为:灰黑色粉末为铁粉、红色粉末为氧化铁.

丙同学认为:灰黑色粉末为活性炭、红色粉末为氧化铁.

[设计方案](1)证明乙同学猜想的实验方案如下:将得出的结论填写在横线上______

(2)根据实验结论可知铁与______和______接触易生锈.

(3)写出红色物质与稀盐酸反应的化学方程式______;

(4)你认为能做食品脱氧剂的物质必须具备的性质(答两点)______、______.

答案

(1)磁铁会吸引灰色粉末,所以灰色粉末是铁粉,红色粉末不会被吸引,说明不是铁,和盐酸反应会生成黄色溶液,说明溶液中存在铁离子,红色粉末中存在+3价的铁,就是氧化铁,故答案为:铁  氧化铁;

(2)从实验中可以知道铁是吸收水和氧气后才转化成的氧化铁,故答案为:氧气、水;

(3)氧化铁和盐酸反应生成氯化铁和水,故答案为:Fe2O3+6HCl═2FeCl3+3H2O;

(4)与食品接触的东西必须是无毒的,还得会除去氧气和水,不能与食品反应,故答案为:能与氧气和水反应、不与食品反应(或无毒等).

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