CHEMISTRY: ACID AND BASES

https://youtu.be/Q6JBAxnPyMo

CLASS ACTIVITY: ACID AND BASES

QUESTION 1:

1.1 Define a base and acid according to Arrhenius's theory. ( 4 )

1.2 Define a base and acid according to Lowy-Bronsted's theory. ( 4 )

1.3 Define what an amphoteric substance is and give two examples of it.( 4 )

1.4  Explain what neutralisation reaction is as well as it's three uses. ( 4 )

1.5 Write the balanced chemical equations for the following reactions:

i. Hydrochloric acid + Sodium hydroxide ( 4 )

ii. Hydrobromide + Magnessium hydroxide ( 4 ) 

iii. Hydrochloric + Aluminium hydroxide ( 4 ) 

In order to complete the previous task; 

Step 1: You must attain knowledge of what a base and an acid is and the two theories about them. 

Step 2: You must understand how the conjugate acid-base pairs system works. 

Step 3 : You must know the different types of neutralisation reaction. 

Step 4 : You must master how to balance chemical equations. 

There are many different types of reactions that can take place. These include acid-base and redox reactions. But we are currently focusing on the acid-base reaction which is called neutralisation reaction.

The Arrhenius definition of acids and bases defines an acid as a substance that increases the concentration of hydronium ions in a solution. A base is a substance that increases the concentration of hydroxide ions in a solution. However this description only applies to substances that are in water and his theory was rejected because of this.

A Bronsted-Lowry acid is a substance that gives away protons  and  base accepts protons. And this theory was accepted.

An amphoteric substance is one that can react as either an acid or base. Water  is an example of an amphoteric substance.

amphiprotic is one that can react as either a proton donor or as a proton acceptor . HCO− 3 and HSO− 4 are examples of amphiprotic substances.

A conjugate acid-base pair refers to two compounds in a reaction (one reactant and one product) that transform or change into the other through the loss or gain of a proton.

Indicators are chemical compounds that change colour depending on whether they are in an acid or in a base.

When an acid reacts with a metal hydroxide a salt and water are formed. The salt is made up of a cation from the base and an anion from the acid. An example of a salt is potassium chloride  which is the product of the reaction between potassium hydroxide  and hydrochloric acid.

When an acid reacts with a metal oxide a salt and water are formed. An example is the reaction between magnesium oxide and hydrochloric acid.

When an acid reacts with a metal carbonate a salt, water and carbon dioxide are formed. An example is the reaction between calcium carbonate and hydrochloric acid.

Kindly thanks to:

• SIYAVULA grade 11 Physical sciences textbook written by the numerous volunteers. 
• STUDY AND MASTER grade 11 physical sciences textbook written by Karin. H Kelder. 

Miss Mjoli created WebQuest for her grade 11 Chemistry class to finish this term's syllabus online because our school is greatly being affected by COVID-19 when we do contact classes. She has  high hopes that they will join the class and do the practise problems given to them  to enhance their understanding on this topic that was started and will be finished online.  

She encourages her leaners to stay indoors and protect themselves from this deadly virus.