MODULE 1: ACIDS - BASES AND PH. NEUTRALISATION

MODULE ACIDS & BASES, PH SCALE. NEUTRALISATION.

These lessons covers the following content: 

-Arrhenius' theory Acids and Bases substances.

-How to decide whether any substance is an acid or a base.

-The measure of pH using the pH-scale.

-The neutralisation chemical reaction of acids and bases to obtain salts.

ACTIVITIES 

In order to carry out the activities besides watching the videos, it is recommended reading carefully the text: "Acid, bases, pH and neutralisation", which is attached to this unit. 

Warm up activity

1. Video: the measure of pH in everyday life.

2. Brainstorming: 

- Why do you think it is important to measure the value of pH?

- Have you ever heard the term Acid? Could you name any acids substances?

- What real situations do you know in which the value of pH is measured?

Task 1 - Introduction to Acids & Bases and pH.

1. After watching the video 1 Acids and bases and pH, fill in the gaps of the following text writing the suitable word. video 1

When water                        , it breaks apart into an equal number of h                ions and  h                       ions.  In contrast, when other substances dissociate, they may 

r                       more hydrogen ions or more hydroxide ions. For example, h                   a                   releases more hydrogen ions as it dissociates, and  s                  h                 releases more hydroxide ions. 
Depending on its                       of hydrogen ions versus hydroxide ions, a substance can be classified as either an             or a                . 
The                    measures how                  or how              a substance is. It ranges from 0 to 14, with 7 being                    . 
When a substance has a pH of 7, like water does, it releases an equal                    of hydrogen and hydroxide ions. 
When a substance has a pH of greater than 7, it’s classified as a base and releases a greater concentration of hydroxide ions.The more hydroxide ions that are released, the m                              the substance is. Bases tend to feel slippery and are often used as household cleaners. Milk of magnesia and                         are both common bases.
When a substance has a pH of less than 7, it’s classified as an acid and releases a greater concentration of hydrogen ions. The                    hydrogen ions that are released, the      m                                the substance is. Acids tend to taste sour. Lemon juice, stomach acid, and coffee are all examples of acids. 

2. Choose the correct answer of the following questions:

1. A hydrogen ion is the same as:

a. electron 

b. proton

c. hydroxide ion

2. Acidic foods can be defined by:

a. salty

b. sour

c. bitter

3. OH- is called:

a. hydrogen ion

b. hydronium ion 

b. hydroxide ion

4. Acids increase the concentration of what in water?

a. H+ ions

b. hydrate ions

c. hydroxide ions

3. Match the following characteristics of acidic or basic subtances:

Task 2 - Value of pH - pH scale -  Neutralisation.

1. After watching the video 2 PH scale, choose the correct answer of the following questions:

1. A beaker containing an acidic solution is added to a beaker containing a basic solution. The pH of the basic solution will:

a. increase

b. decrease

c. keep in the same value

2. When a subtance turns the red litmus paper into blue it is:

a. Basic

b. Acidic 

c. Neutral

3. A solution with a pH = 9 has a hydrogen ions concentration of:

a. 1x 10^-9 moles/liter

b. 9 x 10^-10 moles/liter

c. 9 moles/liter

4. Which substance has the lowest pH?

a. Pure water 

b. Lemon juice

c. Sodium hydroxide

2. Using the pH scale, write the value of pH next to each of the following substances, then classify them into acids, bases or neutral substances according its pH values.

3. How would you test if each of the substances is an acid or a base?

4. How would you find out how acidic or how basic/alkaline the substance tested is?

5. What happens when a acid and a base react? Write the name of the chemistry reaction and explain it.

6. For further information about the industrial application of the neutralisation reaction, watch the video Neutralisation attached to this unit.

7. Let's now test your knowledge with the A&B interactive game!!

Task 3 - Summarizing the content 

In pairs or groups of three, you have to elaborate either a concept map with the main concepts or a poster summarizing the content of the module, you can make use of the following ICT tools:

Concept map: https://www.mindmup.com/

Poster: http://edu.glogster.com/?ref=com

In order to carry out this last activity successfully, it could be also applicable to check the following websites:

https://www.khanacademy.org/science/chemistry/acids-and-bases-topic/acids-and-bases/v/arrhenius-definition-of-acids-and-bases

https://www.thoughtco.com/facts-about-acids-and-bases-603669