college chemistry homework help

college chemistry homework help

Comprehensive Guide to College Chemistry: A Student’s Essential Homework Companion

1. Introduction to College Chemistry

In the process of understanding the world around us, people first classified the materials. They compared their characteristics and properties to decide what to use and do with them. Each human being classified them according to different factors and created his/her own particular world. This book will tell you the characteristics of the materials and how they interact to make new ones. But do not leave the thoughts of the old philosophers. You must look for your own world. Much of what we know was once philosophy. Much that you may know may already be actual chemistry. What you will learn definitely will help you to understand more of the intricate nature of matter, its transformations, its appearance, and its function in an uncertain world. You, the reader with the support of this guide, have to study, work, and enjoy. Remember that if you wish, you can find useful and deeply satisfying work in the realm of modern chemistry. Welcome and be prepared for this wonderful journey!

College chemistry marks a new era in the long history of the study of matter, including its composition and its physical and chemical properties. This book, Comprehensive Guide to College Chemistry: A Student’s Essential Homework Companion, has been prepared by experts in chemistry and teaching, with a clear knowledge of the capabilities and limitations of high school students, including college freshmen. From this special perspective, we present in this guide a solid foundation for getting well introduced to the main essential topics of college chemistry. Starting with some simple and short experiments, the well-structured explanations and the recommended practice problems entertain and help to engage students of any age. Over the following chapters, the topics are presented in a clear and concise way that is easy to understand. These skills and this knowledge are essential to proceed more deeply into the rational study of chemical reactions.

2. Key Concepts and Principles in Chemistry

The discussion begins with atomic structure, a historic study in its own right. It encompasses the structure and behavior of positively charged nuclei surrounded by one or more electrons. Knowing this structure is crucial for understanding chemical reactions and behavior both from quantum mechanical and experimental perspectives. This is closely followed by an important aspect of atomic structure, the organization of electrons to form atoms, the smallest units of elements. An element is a pure chemical substance consisting of one type of atom distinguished by its atomic number, which is the number of protons in its nucleus. Influenced by atomic structure, two or more atoms combined together to create a molecule or compound, the basic unit of chemical compounds. The bonds that hold atoms together are compounded with attraction at the atomic level and follow the laws of chemistry and physics.

The study of chemistry, at the college level, has been divided into numerous specific sub-disciplines, with organic chemistry and biochemistry being the more commonly studied at the undergraduate level. Even at the high school or college “intro” level, the study of chemistry is approached within these sub-disciplines rather than from “first principles” up. Yet all chemistry is based on key underlying principles, and it is these principles that are the focus of this chapter. It is important to have a strong theoretical framework within which to understand the applications. There are six key principles that are covered here: atomic structure, chemical compounds and chemical bonding, the periodic table and periodicity of chemical properties, and chemical reactions.

3. Common Types of Chemical Reactions

A synthesis reaction is just what it sounds like, it is the formation of a complex substance from simpler components. A decomposition reaction is exactly the opposite of a synthesis reaction. A complex substance is broken down into its more simple parts. A single-replacement reaction is a bit more complex than the first two we discussed. In a single-replacement reaction, a single atom replaces another atom in a compound. A double-replacement reaction is a bit more complex than the first two reactions we discussed in this section. In a double-replacement reaction, one complex substance changes places with the other complex substance.

There are several common types of chemical reactions you will encounter in your studies of college chemistry. This section will help you to recognize these reactions and give you an idea of how they will be important in topics to come. While the upcoming units will delve into the mechanisms through which these reactions occur and the factors that govern their rates, it will be helpful for you to understand both qualitative and quantitative descriptions of these and other reactions. Sometimes, a chemical reaction occurs when several simple substances smash together to form more complex compounds. Such rearrangement of atoms results in the formation of a different type of product. For the sake of classification and easiness of learning and utilization of chemical reactions, these are frequently divided into four common types: reassembly of compound type reactions, decomposition type reactions, single replacement type reactions, and double replacement type reactions.

4. Stoichiometry and Balancing Chemical Equations

When given grams of one substance, the desired unit is grams and so on. You may be asked to figure out other aspects of the reaction, but there are specific units needed. The three critical things that the student must understand are: how to balance a chemical equation; how to write a mole to mole ratio starting with a balanced chemical equation; how to write grams to mole(s); moles to gram or volume equation starting with one of these mole-to-mole equations. Limiting reactant (or limiting reagent) is another key concept. This answers the question of which reactant will not run out first. Theoretical yield answers the questions of the maximum amount of product. Defining and Non-defining reactants are also introduced. Introducing a mole is another concept which also requires students to understand mass to mole conversions. Also, the molar mass is introduced as part of the mass-mole relationship. The number of moles-mole-to grams conversion requires a student to know the formula of the substance-helpful for writing equations. In summary, in order to move on to these other areas the student must understand: 1) properly balancing an equation; 2) writing mole-to-mole equations by starting with a balanced chemical equation; and 3) being able to write the required grams-to-moles or moles-to-grams equation by starting with one of these mole-to-mole equations.

Stoichiometry literally means the “measuring of elements,” and it’s about the quantitative relationships and calculations based on chemical equations. The most important aspect for students to understand is how to start with a balanced chemical equation and also be able to use a balanced equation to make mole-to-mole relationships with substances. Stoichiometry is vitally important for anyone who wants to understand chemical reactions and perform calculations. Almost all important concepts in chemistry are explained using stoichiometry. Simply put, stoichiometry measures the mass (in grams) or volume (in the case of gases) of reactants and products in a chemical reaction. Ratios and formulas such as gram to mole, mole to mole, mole to gram, mole to volume, and volume to mole calculations are needed.

5. Practical Applications of Chemistry in Daily Life

Mass Market. The tubs of Country Pleasures soap were found to be surprisingly heavy for the amount of soap remaining in them. Further investigation showed that a bathroom scale had been kept in the same cabinet as the soap, causing the 100-year-old scales to weigh in the bar soap with a zero to ten pound error. In many ways, the backbreaking Sierra treks take her back 17 years, to her hospital cot. Only 1 in 100. The ratio of stored chemical energy in gasoline to the work done by the energy is 1 cal out of 100. Only 1 cal out of 2 gives up work.

The Secret of Soap. When you turn on the tap for a glass of water, you really want the soap to come out. After much research, Tide detergent was introduced in 1946. Tide has additives that let it mix with and react with water quite well. Thus, when the Tide is poured into the wash, it doesn’t just rush right out of the faucet. This mixing ability is called hydrophilicity.

In addition to the biological applications of chemistry discussed in previous chapters—including environmental chemistry, nutrition, and medicine—chemistry finds application in many more aspects of our lives. Close to home are the various products we use every day, such as soaps and detergents, household chemicals, and cosmetics. In fact, nearly all foods and products used for cleaning, health care, and nutrition are chemical mixtures.

Well, among many other things, environmental chemists are hard at work trying to sustain our environment and reverse years of pollution. Just look at their efforts to clean up our air. The engine in your car releases six pollutants. These have been linked to human health problems, like cancer. Environmental chemists are researching ways to cut down on these pollutants. Eight million people say they are allergic to these substances. Normally, one in 1,200 chance of being born with a genetic disorder. But this one in folks is not sick—this fellow has only one real symptom: his skin, which can get soapy. Would you believe his guardian angels come from Irving, Texas? Guardian angels? Well, Quaker is the name of the soap his foster mom uses. “Phosphate-free” is why she uses it.

5. Chapter 25. Chemistry in the Working World: “What Good Is Chemistry?”