问题 问答题

某高钙片(见图)的使用说明书部分内容如下:

【配料】碳酸钙(CaCO3)、甘露醇、乳糖、淀粉、维生素D.

【规格】2.5g/片,每片中含钙0.5g.

【食用方法】每日1次,每次1片,嚼食.

(1)碳酸钙(CaCO3)的相对分子质量为______;碳酸钙中各元素的质量比为Ca:C:O=______.

(2)若此高钙片中所含钙元素都来自碳酸钙,试计算一片该高钙片中所含碳酸钙的质量分数?(含计算过程)

(3)葡萄糖酸钙的化学式为Ca(C6H11O72,其相对分子质量为430.某葡萄糖酸钙保健品的每片含葡萄糖酸钙0.5g,1片高钙片所含钙元素的质量约相当于______片(计算结果取整数)该葡萄糖酸钙保健品所含钙元素的质量.

答案

(1)根据相对分子的质量为组成分子的各原子的相对原子质量之和,碳酸钙的相对分子质量为:40+12+(16×3)=100;根据化合物中各元素质量比=各元素的相对原子质量×原子个数之比,可得碳酸钙中Ca,C,O 元素质量比为:40:12:(16×3)=10:3:12;

(2)一片该高钙片中所含碳酸钙的质量:0.5g÷

40
100
=1.25g;

一片该高钙片中所含碳酸钙的质量分数:

1.25g
2.5g
×100×=50%;

(3)一片该葡萄糖酸钙保健品所含钙元素的质量:0.5g×

40
430
=0.047g;

葡萄糖酸钙保健品的片数为:0.5g÷0.047g≈11(片)

故答案为:(1)100;10:3:12;(2)50%;(3)11

阅读理解

任务型阅读。

     Working vacations are a popular way to see the world and a good way to make some money along

the way. Bill Tylera reporter, talked with Jenny, who just came back from a working vacation in Australia.

     Bill: So how was your trip?

     Jenny: It was fantastic (奇异的) ! The place I went to--Mildura, in Victoria State is known as the

gateway to the outback(内地). I was working at a vineyard(葡萄园) there, as a picker during the grape

harvest. Most of the dried fruits in Australia like raisins (葡萄干) and so on, come from Mildura.

     Bill: Was it hard work?

     Jenny: Mm, yes, it was tiring and it got very boring sometimes. You have to spend around eight hours

a day filling up buckets(桶) with grapes.And it's a six-day week, usually with Saturday off.But the good

thing is that you're working outdoors all the time. And you also get to make something really nice from all

over the world.

     Bill: So, do you have any suggestions for people who want to give it a try?

     Jenny: Well, I'd suggest you only do it if you're quite healthy, and if you don't mind hot weather.

Temperatures in Mildura can reach 25℃ sometimes, so you'll certainly need a sun hat. And don't forget

a water bottle--it's thirsty work!

1. If you like a working vacation you can not only travel, but also make some ______.

2. Jenny thinks her trip in Mildura is______.

3. It's really boring and ______ sometimes as a picker in the vineyard.

4. You should be very ______ if you want to try the work.

5. You should bring a sun hat and a water ______ because of the weather.

单项选择题