ACID,BASE AND SALT By IIN INDRIYATI Biology Teacher of SMP 1 Wonosari

A. Competence Standard : 5. To understand the characteristic of acid, base and salt B. Basic Competence: 5.1 To identify the characteristic of acid, base and salt by using accurate tools and indicators Objective : Objective : 1. Student able to identify the characteristic of acid, base and 1. Student able to identify the characteristic of acid, base and salt after do experiment salt after do experiment

ACID  Acid is a substance that releases hydrogen ion ( H + ) when it’s dissolved in water and a negative ion will be formed according to the following reaction :  Acid H + + negative ion example : example : HCl H+ + Cl – HCl H+ + Cl – (Hydrochloric acid) (Hydrochloric acid) H2SO4 2H+ + SO42- H2SO4 2H+ + SO42- (Sulfuric acid) (Sulfuric acid)

Acid characteristics  There are corosive, meaning they can destroy other materials including metal, marble,  They have sour taste  They can conduct electricity.  They can change blue litmus to red  They have a pH of less than 7

Acids Affect Indicators, by changing their color Blue litmus paper turns red in contact with an acid (and red paper stays red).

Matters that contain acid  Lemon  Tomato  Vinegar  Manggo  Starfruit  etc

Strong Acids  Strong acids are very corrosive. They react with metals and can cause severe burns on the skin. They conduct electricity well.  Strong acids: Hydrochloric HCl Nitric HNO 3 Sulfuric H 2 SO 4 Hydrobromic HBr

Acids have a pH less than 7

Base Base is substance that releases hydroxide ion (OH-) when it’s dissolved in water and positive ions are formed according to the following reaction Base positive ion + OH- Example : NaOH Na+ + OH- Sodium hydroxide Sodium hydroxide NH4OH NH4+ + OH- NH4OH NH4+ + OH- Ammonium hydroxide Ammonium hydroxide

Base characteristics  They caustic, meaning they can damage our skin or other materials  They feel smooth on our hand  They have bitter taste  They can change red litmus to blue

Bases Affect Indicators Red litmus paper turns blue in contact with a base (and blue paper stays blue). Phenolphthalein turns purple in a base.

Bases have a pH greater than 7

Bases Neutralize Acids Milk of Magnesia contains magnesium hydroxide, Mg(OH) 2, which neutralizes stomach acid, HCl. 2 HCl + Mg(OH) 2 MgCl H 2 O Magnesium salts can cause diarrhea (thus they are used as a laxative) and may also cause kidney stones.

Matters that contain base  Soap  Detergent  Thootpaste  Baking soda  Stomach medicine/ Antasid (obat perut)  etc

Common Bases  Sodium hydroxide NaOH  Calcium hydroxide Ca(OH) 2  Magnesium hydroxide Mg(OH) 2  Ammonium hydroxide NH 4 OH

SALT Salt is formed by reaction between acid and base Salt is formed by reaction between acid and base The reaction between Acid and Base is called the neutralization reaction The reaction between Acid and Base is called the neutralization reaction Acid + Base Salt + Water Acid + Base Salt + Water Example : NaCl Example : NaCl HCl (asam) + NaOH (basa) NaCl (garam dapur) + H2O (air) HCl (asam) + NaOH (basa) NaCl (garam dapur) + H2O (air)

Measuring pH Why measure pH? Why measure pH? 4 Everyday solutions we use - everything from swimming pools, soil conditions for plants, medical diagnosis, soaps and shampoos, etc. Sometimes we can use indicators, other times we might need a pH meter Sometimes we can use indicators, other times we might need a pH meter

How to measure pH with wide-range paper 1. Moisten the pH indicator paper strip with a few drops of solution, by using a stirring rod. 2.Compare the color to the chart on the vial – then read the pH value.

Some of the many pH Indicators and their pH range

Acid – Base Indicators Artificial indicators : - Lithmus paper - Universal indicator - Phenolphthalein - Red methil - Blue bromthymol  Natural indicators : - Hibiscus - Turmeric - Red cabbage - Mangosteen

SIFAT – SIFAT SENYAWA ASAM DAN BASA AsamBasa 1, Rasa asam1, Rasa pahit / getir 2, Korosif2, Kaustik 3, Memerahkan lakmus biru3, Membirukan lakmus merah 4, pH < 74, pH > 7 5, Tidak berwarna dengan indikator pp5, Berwarna merah dengan indikator pp 6, Dapat menetralkan senyawa basa6, Dapat menetralkan senyawa asam

Thank’s you See you next time See you next time Good by Good by