Physical Science 4-5: Acids & Bases

​Acids & Bases

Multiple Choice

How many valence electrons does Hydrogen Have?

• 1 Valence electron

• 2 Valence electron

• 3 Valence electron

• 4 Valence electron

• 5 Valence electron

Multiple Choice

What do we call an atom that has a charge?

• Ion

• Molecule

• Isotope

• Metal

Multiple Choice

If Sodium (Na) and Chlorine (Cl) form a compound, it will be held together by...

• Metallic bonds

• Covalent bonds

• Polar bonds

• Ionic bonds

Multiple Choice

The "sharing of electron pairs" describes a(n) ___________________ bond.

• Ionic

• Metallic

• Covalent

• Orbital

Dropdown

If an atom ​

Select answer

electrons, it will become negative.

If an atom ​

Select answer

electrons, it will become positive.

Multiple Choice

How many atoms of carbon (C) are in C₆H₁₂O₆?

• 3
• 6
• 12
• 24

Multiple Choice

The left side of the chemical equation is called

• Products
• Reactants

Multiple Choice

A chemical reaction that absorbs heat is...

• Single replacement
• Exothermic
• Endothermic
• Decomposition

Multiple Choice

Which of the following answers will balance the equation below?
__K + __Br₂ --> __KBr

• 2, 1, 1
• 2, 3, 2
• 2, 1, 2
• 1, 2, 3

​Lesson Objectives

• Describe the Properties of Acids

  • Distinguish between a strong and a weak acid

• Describe the Properties of Bases

  • Distinguish between strong and weak bases

• Describe a reaction between an acid and a base

• Define pH

• Acid: any compound that increases the number of Hydronium ions when dissolved in water.

  • Hydronium = H₃O⁺

• All Acids share certain properties

  • A sour taste

  • Corrosive: Can destroy body tissues

  • Change the color of indicators

  • React with many metals to form Hydrogen Gas

  • Conduct Electricity

​What are Acids?

• Base: Any Compound that makes Hydroxide Ions when dissolved in Water

  • Hydroxide= OH^-

  • They are also called Alkalines

• All Bases share certain properties

  • A bitter flavor

  • A slippery feel

  • Corrosive

  • Change the color of indicators

  • Conduct electricity

• Bases are the opposite of Acids

What are Bases?

What is a Strong Acid or Base?

• Acids and Bases are can be sorted based on how many ions they form when dissolved in water

  • More ions means A stronger acid/base

• Examples of strong Acids: Sulfuric Acid, Nitric Acid, & Hydrochloric Acid

  • Weak acids tend to be found in foods

• Examples of Strong Bases: Sodium Hydroxide, Calcium Hydroxide

  • Weak bases are used in antacid medicines

What happens when Acids & Bases mix?

• When acids and bases mix, they react to combine their ions to make water

• Neutralization Reaction: the reaction of an acid and a base to form a neutral solution of water and a salt

  • The Hydrogen in the Hydronium ions combine with hydroxide ions to make water

Multiple Choice

What is the formula of a Hydronium ion?

• H3O-
• H2O+
• H3O+
• H2O2+

Multiple Choice

A sour taste is a characteristic of:

• acids

• bases

• neutral Solutions

• pH Buffers

Dropdown

A strong acid or base release ​

Select answer

ions in a solution compared to a weak acid or base.

Categorize

Options (10)

Release Hydronium ions

Taste sour

React with metals to produce hydrogen gas

Release Hydroxide ions

Taste bitter

Feel slippery to the touch

Conduct electricity in solution

Neutralize each other

Change color of indicators

corrosive

Organize these options into the right categories

Acids

Bases

Both Acids & Bases

The pH Scale

• We can use indicators to determine if a substance is an acid or a base, but that does not always indicate the strength of the acid

• pH: A value that is used to represent the acidity or alkalinity of a solution

  • pH measures the number of hydronium ions

    • Adding more hydronium ions lowers the pH

  • pH exists on a scale of 1-14

    • 1-6.9 is considered acidic

    • 7 is considered neutral

    • 7.1-14 is considered alkaline

Methods for finding the pH of a substance

• There are several ways to find the pH of a solution

• pH Paper- a strip of paper that is treated with a group of indicator solutions

  • Will change color in response to different pH levels

  • Different papers can get to different levels of specificity

• pH Meter: an electronic device that can measure the amount of electricity conducted through a solution

  • Gives a highly specific number

pH and the environment

• All living things depend on having a steady pH in their environment

  • Some organisms can thrive and need a low pH, while others will die if the pH changes slightly

• Most plants and animals that live in lakes & Streams need a neutral pH to survive

• Most rain is slightly acidic (between 5.5 & 6)

  • Acid rain is between 4 and 4.5

What are Salts?

• Salt: an ionic compound that forms when a metal atom replaces the hydrogen in an acid

  • A positive ion combines with a negative ion to make an ionic compound

Multiple Choice

Which is a characteristic of a base?

• tastes sour

• found mostly in foods

• feels slippery

• turn litmus paper red

Multiple Choice

A(n) _______ is a substance with a pH greater than 7.

• Base
• Acid
• Buffer
• Water

Multiple Choice

Which of the following statements is true concerning acids and bases?

• acids and bases don't react with each other

• acids mixed with bases neutralize each other

• acids mixed with bases make stronger bases

• acids mixed with bases make stronger acids

Multiple Choice

A(n) ______ is a substance with a pH less than 7

• Acid
• Water

• Base
• Buffer

Multiple Choice

True or false: bases are sometimes called alkaline.

• True

• False

Reorder

Four substances were tested for pH: lemon juice (pH 2), baking soda (pH 9), bleach (pH 12), and milk (pH 6). Rank the substances from most basic to Most acidic

• bleach

• baking soda

• milk

• lemon juice

1

2

3

4

• 1
• 2
• 3
• 4