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# General Chemistry

Chemistry is a branch of science which involves the study of matter, composition, structure and properties. Chemistry is the study of matter and the changes that take place with that matter. Matter is everything that you can touch, see, feel, or smell. Matter is defined as anything that has rest mass and volume (space) and is made up of particles. Everything on Earth, everything in our solar system, everything in our galaxy is made up of matter. Because understanding chemistry helps in understand the world around you. The importance of chemistry is that it explains the world around you. If you take classes in chemistry, you'll apply math and logic, which can make studying chemistry a challenge.

Civilizations used technologies that would eventually form the basis to the various branches of chemistry. Examples include fermenting beer and wine, extracting metals from ores, extracting chemicals from plants, making alloys like bronze, making glass, making pottery and glazes and for medicines and perfumes. Chemists later began looking for substitutes of natural resources which were essential but rare to obtain and thus began the search for perfect or precise form of experiments. Chemistry is often called the central science because of its role in connecting the physical sciences, biological, medical and environmental sciences.

## Mastering General Chemistry

1) Success in general chemistry requires a blend of ingredients. It requires a clearly presented body of information which requires lucid instructions.

2) The central principle of modern chemistry revolves around the general ideas of chemistry involving the chemical changes precisely arrangement of molecules.

3) The perfect combinations of atoms into molecules, complicated structures which accounts to the different characteristics of materials.

4) Modern chemistry also emerged very strongly in the 18th century, when researchers began using the systematic balance as a tool in their research.

5) During this time chemists learn to balance essentials in measuring mass, which is nothing but the quantity of matter in the material.

## Principles of General Chemistry

Chemists understood the central principle and the true nature of chemicals, atoms, molecules and thus began the journey of shaping molecules to order. The basic principle of Chemistry involves molding of chemical order beginning with chemical reactions, types, the general characteristics of chemicals and the basic stoichiometry involved in turning these simple elements into complex, essential large molecules.

## General Chemistry Help

The main intention of introduction to General Chemistry is to provide an introduction to the most important principles and applications of chemistry. Its roots lie in descriptive chemistry, which focuses on the physical and chemical characteristics of the elements and their compounds and stresses a practical knowledge of reactivity and applications. Over the years General Chemistry has become more complex with a strong emphasis on the mathematical and theoretical aspects of science.

Chemistry is the study of nature and its behavior with matter. The atom is the basic building block of matter, representing the smallest unit of a chemical element. An atom in turn is composed of subatomic particles called protons, neutrons and electrons. An atom is classified according to the number of protons and neutrons in its nucleus.

## General Chemistry Formulas

A chemical equation is the symbolic representation of a chemical reaction. The coefficients next to the symbols and formulae of entities are the absolute values of the stoichiometric numbers. A chemical equation describes what happens in a chemical reaction. Balancing a chemical equation refers to establishing the mathematical relationship between the quantity of reactants and products. Each side of the chemical equation must represent the same quantity of any particular element.

A chemical formula is a way of conveying data about the proportions of atoms that constitute a particular chemical compound, using a single line of chemical element symbols, numbers, and other symbols, such as dashes, brackets, parentheses, plus (+) and minus (-) signs. From the law of conservation of mass, the mass of the reactants in a reaction must be equal to the mass of the products. More specifically chemical equations must be balanced so that there is the same number of atoms of each element in the products as there is the same number of atoms of each element in the products as there is in the reactants.

## General Chemistry Topics

More than thousands of years, human beings have fashioned natural materials into useful products. The topics included in General Chemistry are:
1. Elements, Compounds, and Mixtures
2. Redox Reactions
3. Liquids
4. Gases
5. Equations of State
6. Units & Conversions
7. Matter
8. Chemical Equations
9. Chemical Reactions
10. Solutions and mixture

## General Chemistry Practice Problems

Below you could see problems

### Solved Examples

Question 1: What is the percentage of lead in galena, PbS? Calculate to 0.1%
Solution:

The formula weight of PbS is obtained by adding the atomic weights of lead and sulfur, which we obtain from the standard table.

Weight of one lead atom (1 Pb) = 207.2 d
Weight of one sulfur atom (1S) = 32.1d
Weight of 1 PbS = 239.3d

Hence 239.3d of PbS contains 207.2d of lead.  We see that 100.0g of PbS would contain

$\frac{207.2d\ of\ lead}{239.3d\ of\ galena}$ X 100.0g of galena = 86.6g of lead

Hence the percentage of lead in galena is 86.6%.

Question 2: A propellant for rocket can be made by mixing powdered potassium perchlorate KClO4, and powdered carbon (carbon black), C with a little adhesive to bind the powdered materials together. What weight of carbon should be mixed with 1000g of potassium perchlorate in order that the products of the reaction be KCl and CO2
Solution:

Taking the equation for the reaction as

KClO4 + 2C $\rightarrow$ KCl + 2CO2

we first calculate the formula weight of KClO4

Weight of 1K = 39.1
weight of ICl = 35.5
weight of 4O = 4 X 16.0 = 64.0
Weight of  KClO4 = 138.6

The atomic weight of carbon is 12.0; the weight 2C is 24.0. Hence the weight of carbon required is 24.0/138.6 times the weight of potassium perchlorate;

$\frac{24.0\ C}{138.6\ KClO_4}$ X 1000g (KClO4) = 173g (C)

Hence about 173g of carbon is required for 1000g of potassium perchlorate.

 More topics in General Chemistry Chemical Equations
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