问题 问答题

实验室常用石灰石和稀盐酸制取二氧化碳.

探究一:气体发生装置的选择:

(1)写出如图1中带标号仪器的名称:a______;b______.

(2)实验室制取二氧化碳气体,发生和收集装置分别选用______和______(填字母),检验集满的方法是______.

探究二:药品的选择

小明对三组药品进行了研究,实验记录如下:

组别药  品实验现象
块状石灰石和稀盐酸产生气泡速率适中
块状石灰石和稀硫酸产生气泡速率缓慢并逐渐停止
粉末状石灰石和稀盐酸产生气泡速率很快
对照实验①③,是探究______对产生二氧化碳速率的影响;对照实验______,是探究不同的酸对产生二氧化碳速率的影响;小明选择第①组药品来制取二氧化碳,该组反应的化学方程式为______.

探究三:生成二氧化碳量的测定.

实验室常通过下列两种途径测量生成二氧化碳的量:

途径一(如图2):由图可知产生二氧化碳的质量为______g.

途径二(如图3):通过排水法测得生成二氧化碳的体积.

由上两种途径比较,你认为哪种途径实验结果更为准确,理由是______.

答案

探究一、

(1)据图可知a是试管,b是集气瓶,故填:试管,集气瓶;

(2)实验室使用固体石灰石和液体稀盐酸制取二氧化碳,选用固液常温型发生装置;二氧化碳能溶于水,不能用排水法收集,二氧化碳的密度大于空气,使用向上排空气法收集;检验二氧化碳是否收集满,可以将燃着的木条放在集气瓶口,观察木条是否熄灭,故填:B,D; 燃着的木条放在集气瓶口,若熄灭则满;

探究二、①③药品的差别是石灰石的状态不同,因此探究的是药品的状态对于反应速率的影响,故填:药品的状态;

①②是石灰石的状态相同,所用酸的类别不同,因此①②探究的是不同类别的酸对反应速率的影响,故填:①②;

碳酸钙和盐酸反应生成氯化钙、水和二氧化碳,故填:CaCO3+2HCl═CaCl2+H2O+CO2↑;

探究三、

途径一、反应前物质的总质量是98.6g,反应后物质的总质量是96.4g,故生成二氧化碳的质量是98.6g-96.4g=2.2g,故填:2.2;

由于二氧化碳能溶于水,使用途径二会使部分二氧化碳溶于水而导致结果不准确,故途径一更准确,故填:途径一更准确,途径二中部分二氧化碳溶于水.

单项选择题
单项选择题

Natural flavorings and fragrances are often costly and limited in supply. For example, the vital ingredient in a rose fragrance is extracted from natural rose oil at a cost of thousands of dollars a pound; an identical synthetic substance can be made for 1% of this cost. Since the early twentieth century, success in reproducing these substances has created a new industry that today produces hundreds of artificial flavors and fragrances.
Some natural fragrances are easily synthesized; these include vanillin, the aromatic ingredient in vanilla, and benzaldehyde, the aromatic ingredient in wild cherries. Other fragrances, however, have dozens, even hundreds of components. Only recently has it been possible to separate and identify these ingredients by the use of gas chromatography and spectroscopy. Once the chemical identity is known, it is often possible to synthesize them. Nevertheless, some complex substances, such as the aroma of fresh coffee, have still not been duplicated satisfactorily.
Many of the chemical compounds making up these synthetics are identical to those found in nature, and are as harmless or harmful as the natural substances. New products must be tested for safety, and when used in food, must be approved by the U.S. Food and Drug Administration.
The availability of synthetic flavors and fragrances has made possible a large variety of products, from inexpensive beverages to perfumed soap to used cars with applied "new car odor."

Which of the following is NOT true according to the last paragraph

A.Synthetic fragrances can be used to make a used car smell like a new one.

B.Synthetic flavors and fragrances have added to the varieties of products.

C.Lemon soap is made out of some delicious lemon.

D.It is likely that a bottle of orange juice is synthesized.