Activity 45 Follow-up• Discuss in your groups why you think

the blue substance that formed during the reaction between copper chloride and sodium carbonate is evidence of a new substance.

— reactants were two clear liquid solutions

— products were a blue solid and liquid

Reactants Products

CuCl2 + Na2CO3 CuCO3 + 2NaCl

Copper chloride + sodium carbonate Copper carbonate + sodium chloride liquid + liquid solid + liquid

The copper carbonate was removed with the filter paper while the sodium chloride remained in solution. The dissolved sodium chloride is much less toxic than the dissolved copper chloride, however, even sodium chloride can cause problems if the concentration becomes too high.

Discuss Analysis Questions

Activity 46: Investigating Solutions of Acids and Bases

What do you know about acids and bases?

• Acidic or basic water outside of a specific pH range violates federal standards for drinking water.

• Higher pH = more basic

• Lower pH = more acidic

• Neutral pH = 7

• Federal water-quality standards require testing for pH, because water with a high or low pH can corrode pipes and release harmful metals from the pipes into drinking water.

Read C-82

• Challenge Question:

How can solutions be tested to identify them as acidic, basic, or neutral?

In this activity you will…

• Work with several acid-base indicators:– Universal Indicator– Phenolphthalein– pH paper

• An indicator is a substance used to detect the presence of specific kinds of chemicals.

Procedure:Follow procedure on pgs. C-83 to C-85

Part A: in step 2 you must discuss a plan and WRITE it in your notebook. Please read step 2.

Step 7: write the cup number you will place each liquid to be tested in on the left hand margin of your table.

Procedure cont.:Use the following information to determine whether the household liquids are an acid, a base, or neutral. Write it in your notebook.

• Water– Neutral

• Hydrochloric Acid (HCl)– Acid

• Potassium Hydroxide (KOH)– Base

• Test the other solutions and compare.

Table 1:Liquids

Distilled water

Hydrochloric acid

Potassium hydroxide

Vinegar

Ammonia w/ water

Baking soda w/ water

Milk

Rubbing alcohol

Sprite w/ water

Phenolphthalein

Write cup numbers based on your plan

Part B: Discussion

• What do you think will happen to the pH of the acid or base if you dilute it with water?– As you add water, the pH gets closer to

neutral.

Analysis Question #1

Acidic Neutral Basic

Hydrochloric Acid

WaterPotassium Hydroxide

Sprite Rubbing Alcohol Ammonia

VinegarMilk

Baking Soda in Water