January/February 2018 – Vol. 31 No. 2

Chemicals and Their Properties Lab

Posted: Tuesday, March 1st, 2011

by Jeff  Bradbury and Patricia Buchanan

Name ____________________

Date _____________________

Partner’s Name ____________

Question: The work of a crime scene investigator (CSI) is to identify certain found liquids or solids in an investigation, how could we find out the identity of an unknown substance?

Purpose: To learn how to classify matter and its changes.

Part 1 Introduction:

Background Information:

1) A pure substance is a sample of matter that has a definite, fixed composition, and the same properties throughout the sample.  Each pure substance has its own set of characteristic properties.

Physical properties can be observed without changing the chemical composition of the substance.  Common physical properties that can be measured without changing the chemical composition are color, melting point, boiling point, solubility, and density.  Taste and odor are usually considered to be physical properties although they depend on the physiology of the person making the observations.

Physical changes do not cause a change in chemical composition, but only a change in appearance.  When a substance simply changes from a solid to a liquid, liquid to a gas or vice-versa (liquid water to solid water, for example) without a change in composition, it is a change in state.  This is a physical change.  (The three physical states are:  gas, liquid, and solid).

Chemical properties describe the ability of a substance to react and change into another substance with a different chemical composition.  The new substance would have new properties.

2) Evidence that a chemical change is taking place includes:

a.  A color change

b.  A solid product, a precipitate is formed

c.  A gas is formed

d.  Energy such as heat, light or electricity is produced.


In today’s lab you will observe some physical properties of elements and some physical and chemical changes. You will be working in groups of 2.

Procedure, Observations, and Data:


Safety goggles must be worn at all times

Hydrochloric acid (HCl) and sodium hydroxide (NaOH) can harm eyes, skin, and clothing. Handle with care. Any acid spilled on the skin should be rinsed with a large volume of water for 15 minutes.

Wash your hands before you leave the lab.

Do not take reagent bottles from the reagent bench to your work station.

Do not pour anything back into a reagent bottle. Offer extra chemical to another student

Do not stick anything into a reagent bottle.

Always clean glassware and spot plates with distilled/deionized water.

Using Chemical and Physical Changes to Identify an Unknown Substance:

At the reagent bench are samples of 7 common substances.  Your instructor will assign you an unknown, which is the same as one of the 7 known substances.  Based on the observations of the chemical and physical properties of the known and unknown substances, you will determine the identity of the unknown.

Procedures 3-5 do not need to be done in order.  You will perform all of the tests on the unknown that you perform on each of the known samples.

1. Observe each sample, including the unknown, and then record your observations as to the color, texture and any other important properties in table 1.

2. In a spot plate place small pea-sized amounts of each substance in 2 different rows of wells. Be careful to note which substance is in which well. Do not use more than a small pea-sized amount, or it will be difficult to perform the tests. (On a paper towel write the name of each substance in the order it is placed in your spot plate, and place this paper towel next to the spot plate.)

3. a. Into the first row of wells of the different substances, put about 1 ml of de-ionized water.  See if the substances dissolve completely or partially, or change in any other way. Record any evidence of change that occurs in table 1.

b. In the row of wells that contains the substances mixed with water, put 3 drops of universal indicator. Record any evidence of change in table 1.

4. In the other row of wells containing the samples put 3 drops of dilute acetic acid (vinegar) and record any evidence of change in table 1 below.

5. Cover your wire gauze with a piece of the aluminum foil that is set out on the reagent bench.  Place about pea-sized amounts of each substance onto the foil covered gauze. Make sure there is plenty of space between each sample on the foil.  Place the gauze on the ring stand and ring apparatus that is in the fume hood.   Light the burner and place the heat under each sample to see if any change occurs. Record any evidence of change in table 1.

Using the data that you recorded in table 1, determine the identity of the unknown sample and answer the questions that follow the table.

Waste: Rinse spot plates in the sink.  Clean spot plates with tap water then deionized water. When aluminum foil has cooled. Wad it up and throw it in the trash.

Table 1: Determining the identity of an Unknown substance

Appearance (1) Reaction with water  (2) Reaction with universal indicator (3) Reaction with vinegar  (4) Reaction with heat   (5)
Sodium Chloride
Sugar (Sucrose)
Baking Powder
Baking Soda

(Sodium Bicarbonate)

Citric Acid
White Flour
Calcium Carbonate
Unknown #

Unknown #     ____________________

Based on you observations in the above table identify the unknown _____________________

Explain the evidence for your answer to the above question:


1.  Explain the difference between a chemical and physical change? (You can use examples from this lab in your explanation.)

2. What was it that you did today that helped you see the difference between a chemical and physical change?

3. What happened when vinegar was added to the powders?


Jeff Bradbury is a professor of chemistry at Cerritos College in Norwalk and is community college director for CSTA; Patricia Buchanan is the Cal Grip Grant Project Assistant at Cerritos College.  The original idea for this activity came from the Los Angeles County Office of Education 15 years ago, which the authors modified.

Written by California Science Teachers Association

California Science Teachers Association

CSTA represents science educators statewide—in every science discipline at every grade level, Kindergarten through University.

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Accelerating into NGSS – A Statewide Rollout Series Now Accepting Registrations

Posted: Friday, January 19th, 2018

Are you feeling behind on the implementation of NGSS? Then Accelerating into NGSS – the Statewide Rollout event – is right for you!

If you have not experienced Phases 1-4 of the Statewide Rollout, or are feeling behind with the implementation of NGSS, the Accelerating Into NGSS Statewide Rollout will provide you with the greatest hits from Phases 1-4!

Accelerating Into NGSS Statewide Rollout is a two-day training geared toward grade K-12 academic coaches, administrators, curriculum leads, and teacher leaders. Check-in for the two-day rollout begins at 7:30 a.m., followed by a continental breakfast. Sessions run from 8:00 a.m. to 4:15 p.m. on Day One and from 8:00 a.m. to 3:30 p.m. on Day Two.

Cost of training is $250 per attendee. Fee includes all materials, continental breakfast, and lunch on both days. It is recommended that districts send teams of four to six, which include at least one administrator. Payment can be made by check or credit card. If paying by check, registration is NOT complete until payment has been received. All payments must be received prior to the Rollout location date you are attending. Paying by credit card secures your seat at time of registration. No purchase orders accepted. No participant cancellation refunds.

For questions or more information, please contact Amy Kennedy at akennedy@sjcoe.net or (209) 468-9027.



MARCH 28-29, 2018
Host: San Mateo County Office of Education
Location: San Mateo County Office of Education, Redwood City

APRIL 10-11, 2018
Host: Orange County Office of Education
Location: Brandman University, Irvine

MAY 1-2, 2018
Host: Tulare County Office of Education
Location: Tulare County Office of Education, Visalia

MAY 3-4, 2018
Host: San Bernardino Superintendent of Schools
Location: West End Educational Service Center, Rancho Cucamonga

MAY 7-8, 2018
Host: Sacramento County Office of Education
Location: Sacramento County Office of Education Conference Center and David P. Meaney Education Center, Mather

JUNE 14-15, 2018
Host: Imperial County Office of Education
Location: Imperial Valley College, Imperial

Presented by the California Department of Education, California County Superintendents Educational Services Association/County Offices of Education, K-12 Alliance @WestEd, California Science Project, and the California Science Teachers Association.

Written by California Science Teachers Association

California Science Teachers Association

CSTA represents science educators statewide—in every science discipline at every grade level, Kindergarten through University.

The Teaching and Learning Collaborative, Reflections from an Administrator

Posted: Friday, January 19th, 2018

by Kelly Patchen

My name is Mrs. Kelly Patchen, and I am proud to be an elementary assistant principal working in the Tracy Unified School District (TUSD) at Louis Bohn and McKinley Elementary Schools. Each of the schools I support are Title I K-5 schools with about 450 students, a diverse student population, a high percentage of English Language Learners, and students living in poverty. We’re also lucky to be part of the CA NGSS K-8 Early Implementation Initiative with the K-12 Alliance. Learn More…

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Written by NGSS Early Implementer

NGSS Early Implementer

In 2015 CSTA began to publish a series of articles written by teachers participating in the California NGSS k-8 Early Implementation Initiative. This article was written by an educator(s) participating in the initiative. CSTA thanks them for their contributions and for sharing their experience with the science teaching community.

2018 CSTA Conference Call for Proposals

Posted: Wednesday, January 17th, 2018

CSTA is pleased to announce that we are now accepting proposals for 90-minute workshops and three- and six-hour short courses for the 2018 California Science Education Conference. Workshops and short courses make up the bulk of the content and professional learning opportunities available at the conference. In recognition of their contribution, members who present a workshop or short course receive 50% off of their registration fees. Click for more information regarding proposals, or submit one today by following the links below.

Short Course Proposal

Workshop Proposal Learn More…

Written by California Science Teachers Association

California Science Teachers Association

CSTA represents science educators statewide—in every science discipline at every grade level, Kindergarten through University.

CSTA’s New Administrator Facebook Group Page

Posted: Monday, January 15th, 2018

by Holly Steele

The California Science Teachers Association’s mission is to promote high-quality science education, and one of the best practice’s we use to fulfill that mission is through the use of our Facebook group pages. CSTA hosts several closed and moderated Facebook group pages for specific grade levels, (Elementary, Middle, and High School), pages for district coaches and science education faculty, and the official CSTA Facebook page. These pages serve as an online resource for teachers and coaches to exchange teaching methods, materials, staying update on science events in California and asking questions. CSTA is happy to announce the creation of a 6th group page called, California Administrators Supporting Science. Learn More…

Written by Guest Contributor

From time to time CSTA receives contributions from guest contributors. The opinions and views expressed by these contributors are not necessarily those of CSTA. By publishing these articles CSTA does not make any endorsements or statements of support of the author or their contribution, either explicit or implicit. All links to outside sources are subject to CSTA’s Disclaimer Policy: http://www.classroomscience.org/disclaimer.

Find Your Reason to Engage

Posted: Monday, January 15th, 2018

by Jill Grace

I was recently reflecting on events in the news and remembered that several years ago, National Public Radio had a story about a man named Stéphane Hessel, a World War II French resistance fighter, Nazi concentration camp survivor, and contributor to the United Nation’s Universal Declaration of Human Rights. The story focused on a book he had published, Time for Outrage (2010).

In it, Hessel makes the argument that the worst attitude is indifference:

“Who is in charge; who are the decision makers? It’s not always easy to discern. We’re not dealing with a small elite anymore, whose actions we can clearly identify. We are dealing with a vast, interdependent world that is interconnected in unprecedented ways. But there are unbearable things all around us. You have to look for them; search carefully. Open your eyes and you will see. This is what I tell young people: If you spend a little time searching, you will find your reasons to engage. The worst attitude is indifference. ‘There’s nothing I can do; I get by’ – adopting this mindset will deprive you of one of the fundamental qualities of being human: outrage.  Our capacity for protest is indispensable, as is our freedom to engage.”

His words make me take pause when I think of the status of science in the United States. A general “mistrust” of science is increasingly pervasive, as outlined in a New Yorker article from the summer of 2016. Learn More…

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Written by Jill Grace

Jill Grace

Jill Grace is a Regional Director for the K-12 Alliance and is President of CSTA.