Search for any substance that you can see outside and inside the school premises and bring it in the classroom. Be back after 15 mintues.
New Friends, New Learning
pH greater than 7
Shake your Acids, Bases and Salts!
IntroductionWe daily use in our life a large number of substances such as lemon, tamarind,common salt, sugar, vinegar etc. Do they have same taste? You find that some of these taste sour, some bitter, some sweet and some salty.
Learning Objectives•To classify the common householdsubstances if they are acids, bases orsalts.•To determine the pH of the substances.•To describe the result of theinvestigation and characteristics of eachsubstance.
A Brief Overview of Acids and Baseshttp://www.youtube.com/watch?v=tNvP3-174_M Watch the short clip
Preliminary Task Search for any substance that you can see outside and inside the school premises and bring it in the classroom. Be back after 15 minutes.
Facilitators Hi I’m Super A, I will help you understand Acids! My name is Super B, I will help you know Bases! And you can call me Super S, I will help you understand Salts!
Hello Kids! Today we will discuss Acid An acid is a substance that gives H+ (Hydrogen) ions when dissolved in water. They are usually compounds of non metals with Hydrogen and sometimes Oxygen. Hi Super A!
Based on the video that you had watched earlier, can you identify the characteristics of an acids?The following are the characteristics of Acids:• Acids have a sour taste• Acids reacts with metals•Acids contains Hydrogen• Many are poisonous and corrosive to skin.• It has a pH less than 7
Some common examples of an Acids are:1. Explosives2. Car Batteries3. Cola4. Vinegar Explosives and car batteries are strong acidswhile cola and vinegar are weak acids.
Now, lets go on with Base. A Base is asubstance that gives OH- (hydroxide) ions when dissolved in water. The solution of a base in water is called an alkali.
Based on the video that you had watched earlier, can you identify the characteristics of a Bases? The following are the characteristics of Bases:• Bases usually taste bitter• Strong Bases are also poisonous and corrosiveto learning• Bases contains Hydroxide ions• Bases feel slippery•It has a pH greater than 7
Some common examples of Bases are:1. Drain cleaner2. Plaster3. Baking powder4. Windex glass cleaner Drain cleaner and plaster are strong baseswhile baking powder and Windex glass cleaner areweak bases.
Reactions between acids and bases When and acid and a base react with each other, the characteristic properties of both are destroyed. This is called neutralization. General formula for acid base reaction: Acid + Base H2O + Salt “Salt” means any ionic compound formed from an acid/base reaction
NeutralizationHCl + NaOH → H 2O + NaClacid + base → water + salt
An indicator is a compound that will change colorin the presence of an acid or base• Red Litmus paper turns blue in base• Blue Litmus paper turns red in acid• Universal indicator (pH paper) Used for the full pH range
pH stands for “potential hydrogen” and is ameasure of how many H+ ions there are insolution. The MORE H+ there are, the LOWER thepH will be.
pH Scale Shows the range of H+ concentrations Low H+ concentrationHigh H+ concentration
A Salt results when an acid reacts with a base.The H+ and OH- ions combine to form water. Thisprocess is called as neutralization. The non metallic ions of the acid and themetal ions of the base form the salt. Acid + Base —-> Salt + Water
The following are the characteristics of Salts:• Salts can be of several different colors• Usually salts are odorless•Salts have pH = 7. They are neutral
Some common examples of Salts are:1. Toothpaste2. Kitchen Salt
Summary Acid is a substance that gives H+ (Hydrogen) ions when dissolved inwater. Acids have a sour taste, reacts with metals and contains Hydrogen.Many are poisonous and corrosive to skin. It has a pH less than 7 and turnsblue litmus paper to red. Some of the common examples of an acid are carbatteries, explosives, cola, vinegar, etc. While Base is a substance that gives OH- (hydroxide) ions whendissolved in water. The solution of a base in water is called an alkali. Itusually taste bitter, contains Hydroxide ions, feel slippery and strong basesare also poisonous and corrosive to learning. It has a pH greater than 7 andturn red litmus paper to blue. Some common examples are glass/draincleaner, baking powder, plaster, etc. Salt results when an acid reacts with a base. The H+ and OH- ionscombine to form water. This process is called as neutralization. Salts can beof several different color , usually odorless and have pH = 7. Some commonexamples are toothpaste, kitchen salt, etc.
Assignment Look for other 15 household substances, check its ingredients and identify why it is an acid, base or salt. Give its formula if possible.