CHEMISTRY - ACIDS & BASES - #10

Acids and Bases

Acids and Bases are two special kinds of chemicals. Almost all liquids are either acids or bases to some degree. Whether a liquid is an acid or base depends on the type of ions in it.

•  If it has a lot of hydrogen ions, then it is an acid.
•  If it has a lot of hydroxide ions, then it is a base. 

pH Scale 

Scientists use something called a pH scale to measure how acidic or basic a liquid is. 

• pH is a number from 0 to 14. 
• From 0 to 7 are acids, with 0 being the strongest. 
• From 7 to 14 are bases with 14 being the strongest base.
•  If a liquid has a pH of 7, it's neutral. This would be something like distilled water. 

Strong Acids and Bases 

Acids with a low pH of around 1 are very reactive and can be dangerous. The same is true for bases of a pH near 13. Chemists use strong acids and bases to get chemical reactions in the lab. Although they can be dangerous, these strong chemicals can also be helpful to us. 

*** Never handle acids or bases in a chemistry lab unless supervised by your teacher. They can be very dangerous and can burn your skin.

Acids and Bases in Nature 

There are many strong acids and bases in nature. Some of them are dangerous and used as poisons by insects and animals. Some are helpful. Many plants have acids and bases in their leaves, seeds, or even their sap. Citrus fruits like lemons and oranges have citric acid in their juice. This is what makes lemons taste so sour. 

Acids and Bases in our Bodies 

Our bodies use acids and bases too. Our stomachs use hydrochloric acid to help digest foods. This strong acid also kills bacteria and helps to keep us from getting sick. Our muscles produce lactic acid when we exercise. Also, our pancreas uses a base called an alkali to help with digestion. These are just a few examples of how the chemistry of bases and acids help our bodies function. 

Other Uses 

Science and technology makes good use of acids and bases. Car batteries use a strong acid called sulphuric acid. Chemical reactions between the acid and lead plates in the battery help make electricity to start the car. They are also used in many household cleaning products, baking soda, and to make fertilizer for crops. 

Fun Facts

• Acids and bases can help neutralize each other.
• Acids turn litmus paper red, bases turn it blue.
• Strong bases can be slippery and slimy feeling.
• Acids taste sour, bases taste bitter.
• Proteins are made up of amino acids.
• Vitamin C is also an acid called ascorbic acid.
• Ammonia is a base chemical.

ACTIVITIES:
ACID & BASES #1

CHEMISTRY - NAMING COMPOUNDS & BALANCING EQUATIONS #9

Naming Chemical Compounds

Chemical compounds are formed when elements are joined by chemical bonds.    These bonds are so strong that the compound behaves like a single substance. Compounds have their own properties that are unique from the elements they are made of. A compound is a type of molecule with more than one element. 

How Compounds are Named 

Chemists have a specific way of naming compounds. It is a standard method of naming compounds that is used by scientists around the world. The name is built from the elements and the construction of the molecule. 

Basic Naming Convention 

First we'll cover how to name molecules with two elements (binary compounds). The name of a compound with two elements has two words. 

To get the first word we use the name of the first element, or the element to the left of the formula. To get the second word we use the name of the second element and change the suffix to "ide" at the end of the word. 

Some examples of adding the "ide": 

O = oxygen = oxide
Cl = chlorine = chloride
Br = bromine = bromide
F = fluorine = fluoride 

Examples of binary compounds: 

NaCl - sodium chloride
MgS - magnesium sulfide
InP = indium phosphide 

What if there is more than one atom? 

In cases where there is more than one atom (for example there are two oxygen atoms in CO₂) you add a prefix to the start of the element based on the number of atoms. Here is a list of the prefixes used: 

# Atoms 1 2 3 4 5 6 7 8 9 10

Prefix mono- di- tri- tetra- penta- hexa- hepta- octa- nona- deca-

** note: the "mono" prefix is not used on the first element. For example CO = carbon monoxide. 

Examples: 

CO₂ = carbon dioxide
N₂O = dinitrogen monoxide
CCL₄ = carbon tetrachloride
S₃N₂ = trisulfer dinitride 

How is the order of the elements determined? 

When there are two elements in a compound, which element goes first in the name? 

If the compound is made of a metal element and a nonmetal element, then the metal element is first. If there are two nonmetal elements, then the first name is the element to the left side of the periodic table. 

Examples:

• In a compound that contains iron and fluoride, the metal (iron) would go first.
• In a compound that contains carbon and oxygen the element to the left on the periodic table (carbon) would go first.

More Complex Naming Rules 

See below for some of the more complex naming rules. 

Naming Metal-Nonmetal Compounds 

If one of the two compounds is a metal, then the naming convention changes a bit. Using the stock method, a roman numeral is used after the metal to indicate which ion is using the charge. 

Examples: 

Ag₂Cl₂ = silver (II) dichloride
FeF₃ = iron (III) fluoride 

Naming Polyatomic Compounds 

Polyatomic compounds use a different suffix. Most of them end in "-ate" or "-ite". There are a few exceptions that end in "-ide" including hydroxide, peroxide, and cyanide. 

Examples: 

Na₂SO₄ = sodium sulfate
Na₃PO₄ = sodium phosphate
Na₂SO₃ = sodium sulfite 

Naming Acids 

Hydro acids use the prefix "hydro-" and the suffix "-ic". 

HF = hydrofluoric acid
HCl - hydrochloric acid 

Oxoacids containing oxygen use the "-ous" or the "-ic" suffix. The "-ic" suffix is used for the acid that has more oxygen atoms. 

H₂SO₄ = sulfuric acid
HNO₂ = nitrous acid
HNO₃ = nitric acid 

COMPOUND & MIXTURE - REVIEW CLOZE

Use this site to learn about compounds & mixtures.  Read carefully for details.  The cloze is a great review.

COMPLETE the COMPOUNDS & MIXTURE cloze.
DUE:  1/10/2014

REVIEW ACTIVITY:
COMPOUNDS & MIXTURES

Make sure to carefully review all notes & sites for preparation for the Quiz, Tuesday, 1/14
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