Science Year 10- Acids and Bases

Neutralisation

Acids react with bases to form compounds with the general name or salts. The reaction is ACID + BASE -> SALT + WATER. It is called a neutralisation reaction because the product is neither an acid or a base. Examples of Neutralisation: -Tooth Decay: Caused when acids from food and sugar residue attack the teeth. Toothpaste is slightly alkaline and neutralises these acids.

Properties of Bases

Bases are METAL OXIDES or METAL HYDROXIDES, e.g CuO and NaOH. Are substances which release OH ions in solution. These OH ions are responsible for the properties of bases. They are the opposite of acids. They feel soapy. Bases that dissolve in water are called Alkalis, alkalis can cancel out acids and make them neutral. Examples containing this are: -Oven Cleaners -Acid Stomach relief

Properties of Acids

Can be gases, liquids, or solids. But they are most often used as solutions in water. Acids are corrosive, attacking many materials including flesh! Acids can be recognised by their reaction with magnesium metal or washing soda (Sodium Carbonate). Both materials dissolve in acids with vigorous fizzing. All acids contain hydrogen. Naturally Occurring Acids are: -Citric Acid -Lactic Acid -Formic Acid Artificial Acids are: -Sulfuric Acid -Hydrochloric Acid -Nitric Acid

Acidity and Agriculture

Conditions needed for good plant growth are: Water, Sun Temperature, an adequate supply of minerals, correct acidity of the farmers soil. Three factors which may cause an increase in soil acidity are: Soil Bacteria, Other Bacteria, Carbonic Acid.

pH Paper

Contains a mixture of dyes which give a range of colours when the paper is dipped into different acids and alkalis. The paper turns red in a strong acid, green in a neutral solution and blue in a strong alkalis. Each colour response to the pH scale .

Common Acids

Formic Acid- Found in ants, when the ant bites a small insect a little formic acid is squirted out. Acetic Acid (Ethanoic Acid)- Found in Vinegar Citric Acid- Causes the sour taste in citrus fruits e.g. Lemons, oranges. Citric Acid is also a white solid that is used to flavour sweets and soft drinks. Tactic Acid- Cream of Tartar, used in baking. Lactic Acid- Found in sour milk, cheese and yoghurt. Carbonic Acid- When carbon dioxide is dissolved in water this is made. Coca Cola and other fizzy drinks contain this. Sulfuric Acid (H2SO4)- Used in car batteries, will burn through your clothes if it is split. Hydrochloric Acid (HCI)- Found in our stomachs to help digest food. Nitric Acid (HNO3)- Found in dyes, Fertilisers and explosives (TNT)

Acids to Know

HCI- Hydrochloric Acid; Makes salt called chlorides HNO3- Nitric Acid; Make salts called nitrates H2So4- Sulfuric Acid; make salts called sulfates

Indicators

Many dyes have different colours depending on whether they are in acidic or alkali solutions. These dyes are called indicators. This can be easily made by warming red cabbage leaves with a mixture of water and industrial methylated spirits. A common indicator is called Litmus, its colours are: RED in an ACID solution PURPLE in an NEUTRAL solution BLUE in an ALKALINE solution

General Equations

Metal + Acid -> Salt +Hydrogen Base + Acid -> Salt + Water Carbonate + Acid -> Salt + Water + Carbon Dioxide

Bases to Know

NaOH- Sodium Hydroxide Ca(OH)2- Calcium Hydroxide NH3- Ammonia NaHCO3- Sodium Hydrogen Carbonate Na2CO3- Sodium Carbonate

Electron

Symbol: E Relative Charge: Negative Where it is found: Shell

Neutron

Symbol: N Relative Charge: Neutral Where it is found: Nucleus

Proton

Symbol: P Relative Charge: Postive Where it is found: Nucleus

Chemical Reactions of Acids and Bases

The salt gets it 'FAMILY NAME' from the acid, and its "FIRST NAME' from the metal. E.g. Calcium + Nitric Acid -> Calcium Nitrate + Hydrogen.

Acids in Everyday Life

These contain acids: -Fizzy Drinks. Acids in fizzy drink enhance the flavour of the drink. It balances the sweetness of the sugar in the drinks and makes them tasty. -Citrus Fruits. Contain citric acid, Vitamin c and ascorbic Acid. The taste of lemon is sharp because of the sour acid. -Vinegar. The scientific name for vinegar is ethanoic acid or acetic acid. Many acids are too dangerous to taste, and stronger acids may be corrosive. Sulfuric Acid can be highly corrosive for example. But it can also be used to make paints, dyes, washing liquid and shampoo.