Properties and Change

Properties are those characteristics of a substance that are responsible for its unique identity. 

Just as hair color, height, sex, and eye color are some of your properties, there are many properties than can be used to identify chemical substances. Chemists divide properties into two classes. Physical properties are those determined without changing the chemical identity of the substance, such as color, physical state, odor, hardness, freezing or boiling temperature, density, and specific heat. Observing some physical properties requires that a physical change occur. 

Identify each observation as a physical property, physical change, chemical property, or chemical change. 

Answer Physical property water only changes physical state. 

Answer Physical change sugar dissolves in water but does not change its identity. Sugar is still as sweet. 

Physical properties Observable characteristics such as density, color. 

Chemical properties smell, hardness, solubility, etc. Properties of a substance that cause specific behavior 

Chemical reaction during chemical reactions Any change that alters the chemical properties of a 

Reactants substance or forms a new substance The substances present at the beginning of a chemical 

Products reaction The substances formed in a chemical reaction 

You are completely surrounded by matter. To better understand this matter—how it affects you, how you affect it, and how it can be manipulated for the benefit of society—you need to build a basic understanding of the types and properties of matter. 

Visit the Chemistry Web site at chemistrymc.com to find links about matter, properties, and changes. 

Chemistry is the study of matter and its properties. Every aspect of these divers environment, under water and on land, is some form of matter. 

Consider the metal objects that are part of the everyday world. A mailbox, for example, stands outside day in and day out, without seeming to change. Under what conditions does metal exhibit chemical change  

Always wear eye goggles, gloves, and an apron when experimenting with chemicals. Use caution when handling an open flame. 

An 18-g sample of element A combines completely with a 4-g sample of element B to form the compound AB. What is the mass of the compound formed  

A substance breaks down into three component elements when it is heated. The mass of each component element is listed in the table below. What was the mass of the substance before it was heated  

Silver iodide powder has been used as an antiseptic and as an agent to seed clouds for rain. Silver iodide is 45.9% silver by mass. If you separate a 50-g sample of silver iodide into its elements, silver and iodine, how much silver would you have  

If 5 g of element A combines with 16 g of element B to form compound AB, how many grams of B are needed to form compound AB2 How many grams of B are needed to form 

During a chemical reaction, 2.445 g of carbon reacts with 3.257 g of oxygen to form carbon monoxide gas. How many grams of carbon monoxide are formed in this reaction  

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A.3 Identify all the physical properties and changes in the following statement The camp nurse measured the temperature of the injured camper and ignited a propane burner when the water began to boil some of the water vapor condensed on the cold window. ... 

A.4 Identify all the chemical properties and changes in the following statement Copper is a red-brown element obtained from copper sulfide ores by heating them in air, which forms copper oxide. Heating the copper oxide with carbon produces impure copper, which is purified by electrolysis. ... 

Chemistry is the science of matter, its properties, and changes. In your classroom work in chemistry, you will learn a great deal of the information that has been gathered by scientists about matter. But, chemistry is not just information. It is also a process for finding out more about matter and its changes. Laboratory activities are the primary means that chemists use to learn more about matter. The activities in the Laboratory Manual require that you form and test hypotheses, measure and record data and observations, analyze those data, and draw conclusions based on those data and your knowledge of chemistry. These processes are the same as those used by professional chemists and all other scientists. 

Temperature. There are three conceivable temperature effects that may influence the particle degradation in an either direct or indirect way, i.e., thermal shock, changes in particle properties and changes in the gas density. 

From a sampling of nineteenth-century statements about the aims of chemistry as a scientific discipline, Robert Friedel found the key words to be "composition," "properties," and "change." In Robert Friedel, "Defining Chemistry Origins of the Heroic Chemist," in Seymour Mauskopf, ed., Chemical Sciences in the Modern World. 

Select the Pin Numbers Visible property and change the value to False ... 

When chemical equations are combined by addition, the standard heats of reaction may also be added to give, the standard heat of the resulting reaction. This is possible because enthalpy is a property, and changes in it are independent of path. In particular, formation equations and standard heats of formation may always be combined to produce any desired equation (not itself a formation equation) and its accompanying standard heat of reaction. Equations written for this purpose often include an indication of the physical state of each reactant and product, i.e., the letter g, l, or s is placed in parentheses after the chemical formula to show whether it is a gas, a liquid, or a solid. This might seem unnecessary since a pure chemical species at a particular temperature and 1 bar or l(atm) can usually exist only in one physical state. However, fictitious states are often assumed as a matter of convenience. 

Through the use of experiments, chemists understand the properties and changes which occur in matter and the various reactions between different substances. 

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