In today’s STEM LabYou will be a Chemical Engineer

We are Chemists at work mixing it up!

• Which causes a chemical reaction, acid with acid, base with base or acid with base?

A Chemical Reactions is . . .Let's start with the idea of a reaction. In chemistry, a reaction happens when two or more molecules interact and the molecules change.

What is an acid & What is a base?

• Acids are defined as chemicals that release hydrogen ions in solutions.

• Bases are called the opposites of acids because they are chemicals that tend to take up hydrogen ions.

• A chemist named Svante Arrhenius came up with a way to define acids and bases in 1887

• This lab will prepare you for the experiment with Mrs. Sandoval.

Acids are found between 0 and 7. Bases are from 7 to 14.

• Scientists use something called the pH scale to measure how acidic or basic a liquid is.

Using a Natural Indicator (Red Cabbage)

• You will test different substances to help you identify it as an acid, a base or neutral.

• We will be testing a variety of household substances and you will record the data on your worksheet

RECORD YOUR OBSERVATIONS

CHEMICAL/SUBSTANCE

COLOR PH SCALE ACID, BASIC OR

NEUTRAL

USE YOUR COLOR CHART TO IDENTIFY SUBSTANCE

• Which causes a chemical reaction, acid with acid, base with base or acid with base?

A Chemical Reactions is . . .Let's start with the idea of a reaction. In chemistry, a reaction happens when two or more molecules interact and the molecules change.

PROBLEM STATEMENT

Properties of Acids and Bases

Properties of Acids• taste sour (don't taste them!)... the word 'acid'

comes from the Latin acere, which means 'sour’

Properties of Bases• taste bitter (don't taste them!)• feel slippery or soapy (don't arbitrarily touch

them!)

HYPOTHESIS

If a base and a base, an acid and an acid, and a base and an acid are mixed, then

will cause a chemical reaction.

Variables• Manipulated variable: the pH level of the substance• Constant variable: (quantities and procedures)• Control: (distilled water (neutral) and substance)• Responding variable: (Evidence of a Chemical Reaction)– gas is produced– a change in temperature – light is produced– a change in color– a solid is formed– a new odor is produced.

MATERIALS must be specific in quantity

• Cups (qty)• Stirs (qty)• Distilled water• Baking soda• Vinegar• Tumeric powder• cast powder• Milk of magnesium• Household liquid• Lemon juice• Washing powder• Bags (sandwich bags)

PROCEDURES begins with a verb

1. Identify the substance as a base or an acid.2. Mix a bases and a base, record observation.3. Mix an acid and an acid, record observation.4. Mix an acid and a base, record observation.5. Continue mixing substances and recording observations.

Illustrations and Pictures

• Illustrate and label your observations, in this case• In your experiments, you must take

pictures of the materials, process and results with out showing any picture of yourself.

Graphs (need quantitative data)

This particular experiment is not good for graphing because there is no measurement that you can record in numbers. What you are recording are your observations by using your senses. If you wanted to record quantitative data, you would have to create a key. Any suggestions?

RESULTSWhat were your results, what does the data recorded say, explain it in your own words.

CONCLUSIONRestate (rewrite) your hypothesis and state whether the data supported or did not support your hypothesis and what you learned (what you concluded after seeing the results.

APPLICATION

Explain who and why this type of research is important to the lives of people here and around the world. Make a connection to careers and organizations.

Think about Alka-Seltzer and the chemical reaction that was purposely researched and invented to help heal the upset stomach.

Data Collection