题干

某同学在气体体积测定仪中用镁和硫酸反应测定1mol氢气体积.完成下列填空:

(1)A中发生反应的离子方程式为  ____ .

(2)检查装置气密性的方法是塞上B瓶的玻璃塞,用橡皮塞塞紧A瓶加料口,当看到 ____现象时,可以确认装置气密性良好.

(3)已知液体量瓶的刻度范围是110~130mL,实验时称取镁带的质量要控制在0.100~0.110g之间,目的是 ____.

(4)完成一次测定实验,需要2次用注射器抽气,其中需要记录的是第  ____次抽出气体的体积.

(5)下列情况会导致实验结果偏高的是 ____(填编号)

a.镁表面的氧化膜没有除尽

b.储液瓶中的液体是水

c.未冷却到室温就读数

d.装置气密性不好.

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答案(点此获取答案解析)

Mg+2H+\u2550Mg2++H2\u2191\uff1b,\u50a8\u6db2\u74f6\uff08B\u74f6\uff09\u5185\u5bfc\u7ba1\u4e2d\u6db2\u9762\u4f1a\u4e0a\u5347\uff0

同类题3

阅读下面会材料,从每题所给的A、B、C、D四个选项中选出最佳选项。

    I graduated from college recently and moved to Washington by myself. While I was in college, it was really easy to meet new people. But "out in the real world", I was finding it really hard. I live in a big city, and it seems like everyone around me is busy or already has all the friends they want. I was feeling so discouraged(沮丧的)and I didn't know what to do, so I called my sister for some advice.

    My sister is five years older than I am, so she's been through all this already. She's been helping me with my problems all my life. When I explained my problem, she understood completely. She said, "Why don't you try meeting people online?"

    "Online? Are you kidding?" I asked. "A friend of mine chatted with a guy online, and when she finally met him face to face, he was nothing like what he said."

    My sister laughed. "You don't have to look for dates online," she said. "But you can find other people like you—people who have just moved to town and want to make some new friends. When I first moved to New York after college, I found a book club and a football team online. I met a lot of people that way."

    "But you don't even like football!" I said.

    "I know," she replied. "But that didn't matter. I still had a lot of fun. You played volleyball in college. Why don't you look for a volleyball team to join? Or an art class?"

    "Yeah! I saw a website about volunteering the other day." I said. "I could volunteer for an organization here in Washington. I bet I could meet a lot of really nice people that way."

    "Good idea!" my sister answered excitedly. "Hey, you might even meet the perfect guy."

    "OK, now you're starting to sound like Mom," I said. "Thanks a lot for the advice. I'm going online right now. I'll let you know what happens. Will you be home tonight?"

    "No, but I'll be here all day tomorrow, so give me a call," my sister replied. "Good luck!"