Objective:
The objective of this lab is to identify different classes of matter based on the physical properties of different elements and compounds and to determine whether the changes observed are physical or chemical changes.
Background and Scientific Principles:
Matter is divided into the four basic states of solid, liquid, gas, and plasma. Matter is classified based on composition. Homogeneous matter is matter that appears the same throughout a mixture. Heterogeneous matter is matter that has differing appearances throughout the mixture. The concept map below shows the relationship between some of the primary classes of matter.
Matter is identified by its characteristic physical properties. Physical properties are those that can be determined without altering the composition of the substance, such as, color, odor, density, strength, elasticity, magnetism, and solubility. Chemical properties are descriptions of the substance and its reactions with other substances to create new substances with new properties. These chemical properties are identified through chemical reactions. Evidence of a chemical reaction possibly occurring can be seen through a color change, temperature change, evolution of a gas, and the formation of a new substance. This lab will only focus on the physical properties of matter.
States of matter
solids are rigid and have shapes
liquids flows and take the shape of the container
gases are less dense than liquid and occupy all parts of a vessel.
Physical and Chemical Properties
A chemical property is the ABILITY of a substance to react with something else (air, water, acids, etc.)
Chemical properties of substances are related to the kinds of chemical changes that the substances undergo.
Example: Iron reacts with atmospheric oxygen to form iron (II) oxide (commonly known as rust).
Physical properties include color, density, hardness, melting point, boiling point or freezing point, electrical and thermal conductivities.
Some physical properties of a substance depend on the conditions such as temperature and pressure in which they are measured.
Example CO2 is gas at atmospheric pressure but at lower pressure is a solid.
Physical and Chemical Changes
Physical change occurs when no new compound or molecule is formed. The element or the compound can be retrieved back to its original state. More common observation of a physical change is a change of physical state. An example is ice to water to steam.
Chemical change occurs when a new compound or molecule is formed and one or more substances are used up. Evidence that chemical change has occurred is permanent change in color, gas evolution, and precipitation.
Solubility
Solids can have partial to complete solubility in a solvent. A solid that completely dissolves is considered soluble. The solid "disappears" and no crystal remains.
Partially soluble solids at times will appear less than the original volume. At times, colored compound that partially dissolve will color the solvent.
Liquids that are soluble will dissolve into a homogeneous solution.
Liquids that are partially soluble or insoluble will form layers. Insoluble liquid will go to the bottom of the solvent if it is denser than the solvent and float up to the top if it less dense than the solvent.
Questions you should be asking yourselves as you perform the experiment
What are the physical characteristics of a metal, non-metal and a gas?
What is the difference in observation of an insoluble solid vs. insoluble liquid.
What is the difference between a physical change vs. chemical change?
What patterns of evidence do you note in your observations of physical change? Chemical change?
Do you note any difference in the physical and chemical changes of elements or compounds?
Materials and Supplies:
Procedure:
Data Table and Calculations:
Fill in the data table based on your observations.
*Class of Matter - at home, look up each of these substances in a dictionary or on the internet. Determine if the substance is an element or compound or mixture.
Print off the laboratory worksheet linked
here. Answer all questions on the sheet and turn in pages along with
the rest of your experiment write-up.
Sources