问题 填空题

(5分)KNO3和NaCl在不同温度时的溶解度如下表所示。请回答下列问题:

温度/℃010203040506070
溶解度/gKNO313.320.931.645.863.985.5110138
NaCl35.735.836.036.336.637.037.337.8
(1)依据上表数据,绘制出KNO3和NaCl的溶解度曲线如图所示:

图中能表示KNO3溶解度曲线的是            (填“A”或“B”)

(2)由表中数据分析可知,KNO3和NaCl在某一温度时具有相同的溶解         度,则温度的范围是                          

(3)某兴趣小组做了一下实验:

上述实验过程中得到的溶液一定属于不饱和溶液的是                   (填数字序号),将⑤继续冷却至10℃,过滤,共可回收得到KNO3固体                 g;

(4)硝酸钾中含有少量氯化钠时,可通过                   (填“蒸发结晶”或“降温结晶”)的方法提纯。

答案

(1)A(2)20℃至30℃时

(3)①③④    59.1g

(4)降温结晶

题目分析:(1)根据表中数据可知:在0℃时硝酸钾的溶解度小于氯化钠的溶解度;而根据图像可知:在0℃时A的溶解度小于B的溶解度;所以A表示硝酸钾的溶解度曲线。

(2)根据表中数据可知:在20℃时硝酸钾的溶解度小于氯化钠的溶解度;在30℃时硝酸钾的溶解度大于氯化钠的溶解度;所以二者在温度为20℃至30℃时溶解度相等。

(3)在20℃时硝酸钾的溶解度为31.6g。即在20℃温度下,硝酸钾在100g水里达到饱和状态时所溶解的质量为31.6g。因此题目中向100g水里25g硝酸钾时,所得溶液①为不饱和溶液;向溶液①再加25g硝酸钾时,硝酸钾的总质量为50g;而20℃时硝酸钾最多溶解31.6g,此时溶液②为饱和溶液。溶液②加热至50℃时,此时硝酸钾的溶解度为85.5g。此时硝酸钾的总质量为50g,所以溶液③为不饱和溶液。再加入30g硝酸钾,硝酸钾的总质量为80g,所以溶液④仍为不饱和溶液。溶液④冷却至20℃,得到的溶液⑤中硝酸钾的总质量为80g,硝酸钾的溶解度为31.6g。此时溶液为饱和溶液。所以溶液①③④为不饱和溶液。  将溶液⑤继续冷却至10℃,硝酸钾的溶解度为20.9g,此时硝酸钾的总质量为80g。所以析出固体的质量为:80g—20.9g=59.1g

(4)当温度变化时,硝酸钾的溶解度变化较大,而氯化钠的溶解度变化较小。所以可通过降温结晶的方法提纯硝酸钾。

阅读理解

Shopping is not as simple as you may think! There are all sorts of tricks at play each time we reach out for that particular brand (商标) of product on the shelf.

Colouring, for example, varies according to what the producers are trying to sell. Health foods are packaged (包装) in greens, yellows or browns because we think of these as healthy colours. Ice cream packets are often blue and expensive goods, like chocolates, are gold or silver.

When some kind of pain killer was brought out recently, researchers found that the colours turned the customers off because they made the product look weak and ineffective. Eventually, it came on the market in a dark blue and white package—blue because we think of it as safe, and white as calm.

The size of a product can attract a shopper. But quite often a bottle doesn’t contain as much as it appears to.

It is believed that the better-known companies spend, on average, 70 per cent of the total cost of the product itself on packaging!

The most successful producers know that it’s not enough to have a good product. The founder of Pears soap, who for 25 years has used pretty little girls to promote(推销)  their goods, came to the conclusion: “Any fool can make soap, but it takes a genius (天才) to sell it.”

小题1:Which of the following may trick a shopper into buying a product according to the text?

A.The cost of its package.

B.The price of the product.

C.The colour of its package.

D.The brand name of the product.小题2:The underlined part “the colours turned the customers off”(in Para. 3 ) means that the colours _____.

A.attracted the customers strongly

B.had weak effects on the customers

C.tricked the customers into shopping

D.caused the customers to lose interest小题3:Which of the following is the key to the success in product sales?

A.The way to promote goods.

B.The discovery of a genius.

C.The team to produce a good product.

D.The brand name used by successful producers.小题4:Which of the following would be the best title for this text?

A.Choice of Good Products

B.Disadvantages of Products

C.Effect of Packaging on Shopping

D.Brand Names and Shopping Tricks

判断题 案例分析题