若成人每天食用7.5g加碘食盐，就能同时摄人（成人每天需要的）150×10-6g碘．问每千克加碘食盐中含______g碘．若加入的是碘化钾或碘酸钾（相对分子质量分别为166和214），则每千克食盐中应加______g碘化钾或______g碘酸钾（KIO3）．加碘化钾的食盐若保存不当，半年中碘损失约90%，损失碘的原因是______．（提示：单质碘会升华）
7.5g加碘食盐的质量为：7.5g×1×10-3kg/g=7.5×10-3kg
每千克加碘食盐中含碘的质量为：
=2.0×10-2g150×10-6g 7.5×10-3kg
每千克食盐中应加碘化钾的质量为：0.02g÷
×100%=2.61×10-2g127 166
每千克食盐中应加碘酸钾（KIO3）的质量为：0.02g÷
×100%=3.37×10-2g127 214
加碘化钾的食盐若保存不当，容易被空气中的氧气氧化成碘单质；
故答案为：2.0×10-3； 2.61×10-2； 3.37×10-2； 被空气中的氧气氧化成碘单质．
根据短文内容，用方框中所给单词的适当形式填空。每词限用一次。
Drink at ___2____8 glasses of water a day. You may need even more water if you are exercising. Breakfast is the most important meal of the day. You will have more energy after eating breakfast. Eat a light lunch every day. If you don’t have time to go out, take a sandwich in the morning with you for a __3______ lunch. We should eat fruit and vegetables every day. Add a banana to your breakfast, have a salad with lunch, and eat at least one vegetable for ___4____. Try to have dinner at least 3 hours before you go to bed. Your body needs time to digest most of the food before you rest__5____the next 8 hours. |