LAB 4 Observations of Chemical and Physical Change Part 1

f) Sulfur trioxide changing into sulfuric acid in the atmosphere is a chemical property because it shows what is happening to the sulfur trioxide as it is reacting with the water in the atmosphere. This is is the behaviour of sulfur trioxide in a chemical change.

Purpose: The purpose of this experiment is to observe chemical changes in common consumer products to determine if the chemicals are basic, acidic, or remain neutral when mixed with other chemicals.

A physical change includes a change in the material without affecting its composition, such as the physical state change. However, a chemical change includes the change in the composition of the substance. The change in color, formation of a gas or a solid product, and the production of energy are the evidences of a chemical reaction, thus, of a chemical change.

A physical change is one that affects only the physical properties of a substance, while a chemical change alters a substance at the molecular level.

Examine a piece of nichrome wire. On the data sheet, record the color and the luster of the metal. Use a forceps to hold the wire in the flame of your burner for about two minutes (recall where the hottest part of the flame is located). Describe the appearance of the wire while held in the hottest part of the flame. Allow the wire to cool and reexamine it. From your observations, determine if there was a physical or a chemical change. Give specific reasons for your conclusions. Save the nichrome wire for step #2.

A chemical reaction is a process that involves change of the molecular or ionic structure of a substance, as opposed to a change in physical form or a nuclear reaction. The key concepts of a chemical reaction are:

| Can see particles of both. When mixed with water salt dissolves and sand is left.After filter sand is left and salt-water goes through.After evaporations of salt-water, salt is only left in dish.

This document is not meant to be a substitute for a formal laboratory report. The Lab Report Assistant is simply a summary of the experiment’s questions, diagrams if needed, and data tables that should be addressed in a formal lab report. The intent is to facilitate students’ writing of lab reports by providing this information in an editable file which can be sent to an instructor.

Complete Table 2 and answer Post Lab Questions 1 through 4 in complete sentences on the Week Three Lab Reporting Form.

This document is not meant to be a substitute for a formal laboratory report. The Lab Report Assistant is simply a summary of the experiment’s questions, diagrams if needed, and data tables that should be addressed in a formal lab report. The intent is to facilitate students’ writing of lab reports by providing this information in an editable file which can be sent to an instructor.

Instructions: This is a two-part lab. Be sure to follow all steps given in the lab and complete all sections of the lab report before submitting to your instructor.

Note: Your prelab/lab report is to be done in your carbon copy lab notebook (sold in FIU bookstore)

This document is not meant to be a substitute for a formal laboratory report. The Lab Report Assistant is simply a summary of the experiment’s questions, diagrams if needed, and data tables that should be addressed in a formal lab report. The intent is to facilitate students’ writing of lab reports by providing this information in an editable file which can be sent to an instructor.

Chemical reactions make new things by rearranging other things. In a chemical reaction, the main change that occurs relates to the way atoms are bonded to each other, in order to change those connections, bonds must be broken and new bonds be formed.

An example of a chemical change that one could come into contact with daily is rust. Air and iron are the reactants in this situation while rust is the product. The chemical equation for this reaction would look roughly like this, O+FE= OFE or rust. This is clearly a chemical change because you cannot reverse it meaning you cannot take rust and pull out the iron to leave air or vise versa. All chemical changes are finite. One other example of a chemical change is the burning of any substance. For example if one were to burn a sheet of paper it would create ash. This chemical change is finite because you cannot change ash back into paper.