首页
外语
计算机
考研
公务员
职业资格
财经
工程
司法
医学
专升本
自考
实用职业技能
登录
外语
"Physical and Chemical Properties and Changes" Sugar, water, and aluminum are different substances. Each substance has specif
"Physical and Chemical Properties and Changes" Sugar, water, and aluminum are different substances. Each substance has specif
admin
2018-07-24
60
问题
"Physical and Chemical Properties and Changes"
Sugar, water, and aluminum are different substances. Each substance has specific properties that do not depend on the quantity of the substance. Properties that can be used to identify or characterize a substance—and distinguish that substance from other substances—are called characteristic properties. They are subdivided into two categories: physical properties and chemical properties.
The characteristic physical properties of a substance are those that identify the substance without causing a change in the composition of the substance. They do not depend on the quantity of the substance. A Color, odor, density, melting point, boiling point, hardness, metallic luster or shininess,
ductility
,
malleability
, and
viscosity
are all characteristic physical properties. For example, aluminum is a metal that is both ductile and malleable. B Another example of a physical property is water. Whether a small pan of water is raised to its boiling point or a very large kettle of water is raised to its boiling point, the temperature at which the water boils is the same value, 100 degrees C or 212 degrees F. C Similarly, the freezing point of water is 0 degree C or 32 degrees F. These values are independent of quantity. D
Characteristic properties that relate to changes in the composition of a substance or to how it reacts with other substances are called chemical properties. The following questions pertain to the chemical properties of a substance.
1. Does it burn in air?
2. Does it decompose (break up into smaller substances) when heated?
3. What happens when it is placed in an acid?
4. What other chemicals will it react with, and what substances are obtained from the reaction?
Characteristic physical and chemical properties—also called intensive properties—are used to identify a substance. In addition to the characteristic physical properties already mentioned, some intensive physical properties include the tendency to dissolve in water, electrical conductivity, and density, which is the ratio of mass to volume.
Additional intensive chemical properties include the tendency of a substance to react with another substance, to tarnish, to corrode, to explode, or to act as a poison or carcinogen (cancer-causing agent).
Extensive properties of substances are those that depend on the quantity of the sample, including measurements of mass, volume, and length. Whereas intensive properties help identify or characterize a particular kind of matter, extensive properties relate to the amount present.
If a lump of candle wax is cut or broken into smaller pieces, or if it is melted (a change of state), the sample remaining is still candle wax. When cooled, the molten wax returns to a solid. In these examples, only a physical change has taken place; that is, the composition of the substance was not affected.
When a candle is burned, there are both physical and chemical changes. After the candle is lighted, the solid wax near the burning wick melts. This is a physical change; the composition of the wax does not change as it goes from solid to liquid. Some of the wax is drawn into the burning wick where a chemical change occurs. Here, wax in the candle flame reacts chemically with oxygen in the air to form carbon dioxide gas and water vapor. In any chemical change, one or more substances are used up while one or more new substances are formed. The new substances produced have their own unique physical and chemical properties.
The apparent disappearance of something, like the candle wax, however, is not necessarily a sign that we are observing a chemical change. For example, when water evaporates from a glass and disappears, it has changed from a liquid to a gas (called water vapor), but in both forms it is water. This is a phase change (liquid to gas), which is a physical change. When attempting to determine whether a change is physical or chemical, one should ask the critical question: Has the fundamental composition of the substance changed? In a chemical change (a reaction), it has, but in a physical change, it has not.
Glossary
ductility: can be drawn into wire malleability: can be shaped viscosity: thick, resistant to flow
Complete the table by matching the phrases on the left with the headings on the right. Select the appropriate answer choices and drag them to the characteristic properties to which they refer. TWO of the answer choices will NOT be used. This question is worth 4 points.
To delete an answer choice, click on it. To see the passage, click on View Text.
Properties
A Color of the substance B Reaction in an acid C Decomposition in heat D Temperature at which it boils E The tendency to shine F The inclination to tarnish G The shape of the substance H Toxic if swallowed or inhaled I The relative amount in nature
Physical Properties
-
-
-Chemical Properties
-
-
-
-
选项
答案
Physical properties: A, D, E Chemical properties: B, C, F, H Not used: G, I
解析
转载请注明原文地址:https://www.kaotiyun.com/show/G3fO777K
0
托福(TOEFL)
相关试题推荐
WhatdidPhoebefinddifficultaboutthedifferentresearchtechniquessheused?ChooseFIVEanswersfromtheboxandwritethe
Completetheflowchartbelow.WriteNOMORETHANTWOWORDSforeachanswer.ExpertiseincreativewritingB
Completetheflowchartbelow.WriteNOMORETHANTWOWORDSforeachanswer.ExpertiseincreativewritingB
Whichattitudeisassociatedwiththefollowingpeopleduringtheconversation?ChooseSIXanswersfromtheboxandwritetheco
"MigrationfromAsia"TheAsianmigrationhypothesisistodaysupportedbymostofthescientificevidence.Thefirst"hard"
"MigrationfromAsia"TheAsianmigrationhypothesisistodaysupportedbymostofthescientificevidence.Thefirst"hard"
"MigrationfromAsia"TheAsianmigrationhypothesisistodaysupportedbymostofthescientificevidence.Thefirst"hard"
PatentsandInventionsWhenaninventionismade,theinventorhasthreepossiblecoursesofactionopentohim:first,hec
PatentsandInventionsWhenaninventionismade,theinventorhasthreepossiblecoursesofactionopentohim:first,hec
随机试题
回族女子戴绿色肩盖头的是()。
表面处理对防腐蚀工程的质量至关重要,基体表面的粗糙度、清洁度、()三个方面能够决定防腐工程的施工质量。
心肌细胞和骨骼肌细胞的区别()。
正常月经来潮是由于()
根据《机动车排放污染防治技术政策》,柴油车主要排放的污染物有()。
某农机生产企业为增值税一般纳税人,2016年5月发生以下业务:(1)外购原材料,取得普通发票上注明价税合计,50000元,原材料已入库;另支付给运输企业运输费用1909.09元,取得一般纳税人开具的增值税专用发票。(2)外购农机零配件,取得的增值税专用
下列关于商业银行风险的说法,不正确的有()。
陕西省有世界文化遗产1处,它是()。
不同时代不同人群心目中的长城所象征的底蕴并不那么一致,古代高明的政治家运用这条军事防线和经济、文化聚汇线,调控了中原政权与北方少数民族的关系,把农业经济与游牧经济融合在一起,为保护发展生产力开拓了新路,他们也通过这播撒封建文明的文化带,有效地促进了民族融和
ORACLE是关系型数据库管理系统,它采用【】语言作为数据库的开发和维护语言。
最新回复
(
0
)