DO NOW…..

1. Write down today’s objective in your binder.

2. Using your notes from our Homeostasis: Investigating Breathing Rate Lab, answer the question:

“What two respiratory gases affect breathing rate?”“Which gas changes the condition of the blood?”

LAB: DETERMINING A LIQUID AS ACIDIC, BASIC OR NEUTRAL

O B J E C T I V E I S T O D E T E R M I N E T H E P H O F C O M M O N H O U S E H O L D S U B S T A N C E S A N D U S E T H I S I N F O R M A T I O N T O I D E N T I F Y T H E S U B S T A N C E A S A N A C I D I C , B A S I C O R N E U T R A L S O L U T I O N .

VOCABULARY BUILDING: BE SURE THAT YOU CAN DEFINE THESE TERMS BEFORE DOING THE LAB

Ion

Dissociate

Hydrogen ion

Hydroxide ion

Neutral

Acidic

Basic

WATER IN A GLASSHOW DO THE MOLECULES APPEAR?

Above is a diagram of the way in water molecules can look in the glass to the left. The water molecules breaks into ions, hydroxide and hydrogen.

Diagram below shows Water molecules with 2 hydrogenAtoms and 1 oxygen atom

PAPER INDICATOR -

Called pH paper -Indicates the presence and amount

of H+

Click icon to add picture

SET UP

FOR T

HE LAB

Test

tubes

con

tain

var

ious

house

hold s

ubstan

ces

Above he pH paper is the light yellow colored as shown by the arrow. This is the paper you used to id the acid and base or neutral liquid. The red and blue paper are something else. A beaker of distilled water is available to clean the stirring rod after each application of a substance on the paper. Preventing contamination of solutions is very important.

Liquid pH paper color

pH # Acid, Base, or Neutral

Vinegar Acid

Milk Neutral or acid

Detergent Base

Ammonia Base

Gatorade Acid

Water Neutral

Baking soda water

Base

Spray cleaner Base

Orange juice Acid

Soda AcidData Table indicates if the liquid is and acid, a base, or neutral liquid. Your results may or may not be the same. These are the expected results. You would not be marked wrong if the data correctly matches with the type of liquid.

USE THIS SLIDE TO HELP YOU COMPARE THE MAKEUP OF TWO SOLUTIONS (QUESTION #2 IN ANALYSIS OF EXPERIMENT)

Rule: As you move from right to left, the number of Hydrogen ions decreases.

How does a pH of 3 and a pH of 5 compare?How does a pH of 8 and a pH of 12 compare?Does a neutral liquid have hydrogen ions?Does a pH of 9 have hydrogen ions?

Strong Acid

Strong Acid

WeakAcid

Neutral

Weak Base

Strong Base

Vinegar x

Milk x

Detergent

x

Ammonia

x

Gatorade

x

Water x

Baking soda

x

Spray cleaner

x

Orange juice

x

Soda x

Data Table indicates theexpected answers. Yours may be different but would be correct if your data matches youranswer.

CHALLENGE:

People usually say that the blood is neutral. A pH of 7 denotes neutral. Fr7 can be called acidic or basic (alkaline) when talking about the condition of human blood. Why?