8th Grade: Acids & Bases 🧪

Interactive Lesson • $\text{pH}$ Scale • Properties Quiz

Chemistry in the Kitchen and Lab! 🍋

  **Acids** and **Bases** are two fundamental types of chemical compounds that are found everywhere, from your kitchen pantry to your body. Their properties are defined by the way they behave in water, specifically how they relate to the concentration of $\text{H}^+$ (hydrogen) ions and $\text{OH}^-$ (hydroxide) ions.

  The most important concept is the $\text{pH}$ **Scale**, which measures how acidic or basic a substance is.

 
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Streak: ${streak}

The $\text{pH}$ Scale: From 0 to 14 📏

The $\text{pH}$ scale runs from 0 (most acidic) to 14 (most basic). It is a **logarithmic scale**, meaning a change of 1 $\text{pH}$ unit means a tenfold ($10\text{x}$) change in strength!

 
0 - Strong Acid
 
7 - Neutral
 
14 - Strong Base
 

Acids ($\text{pH} < 7$)

 

Release $\text{H}^+$ ions in water. **Taste sour** (like lemons) and turn litmus paper **red**. Examples: Stomach acid, vinegar.

 

Bases ($\text{pH} > 7$)

 

Release $\text{OH}^-$ ions in water. **Taste bitter**, feel **slippery** (like soap), and turn litmus paper **blue**. Examples: Baking soda, drain cleaner.

Video: Neutralization 🤝

Watch what happens when an acid meets a base. They cancel each other out!

 
 
 

Practice Problems (Property Identification)

Read the property and click whether it describes an Acid or a Base.

 
   
1) Turns blue litmus paper red.
   
               
   
 
 
   
2) Has a $\text{pH}$ value of 11.5.
   
               
   
 
 
   
3) Reacts with a metal (e.g., zinc) to produce $\text{H}_2$ gas.
   
               
   
 
 
   
4) Feels slippery and is often used in cleaning products.
   
               
   
 

⚡ $\text{pH}$ Scale Challenge!

Drag the item to the $\text{pH}$ region you think is correct.

 
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Correct: 0
 
Where does this item belong on the $\text{pH}$ scale?
 
     
 

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