Essays Tagged: "Chemical substance"

An Ecosystem's Disturbance by a Pollutant

tem (Freeman, 122).Now using the approach of classical toxicology we study the poisoning effects of chemicals on individual animals resulting in lethal or sublethal effects. Effects on individuals may ... (the lethal dose for 50% of test animals) values, scientist can judge the relative toxicity of two chemicals. For example, a chemical with an LD50 of 200 milligrams per kilogram of body weight is hal ...

(83 pages) 282 0 3.7 Jan/1996

Subjects: Science Essays > Environmental Science

Title: Separation by Filtration and Crystallisation. The first year 11 Chem prac write up... the structure is at least correct... :p

Aim: To separate substances by the properties of filtering and crystallisation.Apparatus and Chemicals: - balance.- 100mL-beaker (2).- Filter funnel stand and filter funnel.- Bunsen, Tripod and ... e solubilities in water of the two substances in part B is that the Copper Chloride an water form a chemical reaction thus leaving them inseparable while the Sodium Chloride and water merely form a ph ...

(2 pages) 24 1 4.0 Feb/2004

Subjects: Science Essays > Chemistry

Different Aspects Of Science

s, or compounds. A mixture is when matter consists of two or more substances mixed together but not chemically combined. Mixtures can be classified according on how mixed they are. Heterogeneous mixtu ... elements. Pure substances that are made of more than one element are compounds.Physical change and chemical change are similar but not exactly alike. Physical change is when the appearance, texture, ...

(4 pages) 51 1 5.0 Jun/2004

Subjects: Science Essays

Psychoactive Drugs

Psychoactive drugs are chemical substances that alter mood, behavior, perception, or mental functioning. Throughout history ... eat patients with severe mental illness.Psychoactive substances exert their effects by modifying biochemical or physiological processes in the brain. The message system of nerve cells, or neurons, rel ... rocesses in the brain. The message system of nerve cells, or neurons, relies on both electrical and chemical transmission. Neurons rarely touch each other; the microscopic gap between one neuron and t ...

(2 pages) 64 0 4.5 Aug/2004

Subjects: Humanities Essays > Health & Medicine

Testing for Biomolecules

Aim:The objective is to identify specific chemical substances within a cell and to be able to verify the presence or absence of each one in a ... e in a cell or food substance for future testing.Hypothesis:The identification of each biomolecular chemical substance should be verified successfully, as well as determining if it is present or absen ... olecule.Conclusion:It was learnt from this experiment and its results that the indentification of a chemical substance in a cell is achievable and the verification of biomolecular presence in the cell ...

(6 pages) 56 1 4.7 Sep/2004

Subjects: Science Essays > Biology

The Building Blocks of Biology

r. Be sure to explain how this bond works.In science, a molecule is the smallest particle of a pure chemical substance that still retains its chemical composition and properties. A molecule consists o ... n and properties. A molecule consists of two or more atoms joined by shared pairs of electrons in a chemical bond. It may consist of atoms of the same chemical element, as with oxygen (O 2), or of dif ...

(2 pages) 16 0 3.0 Apr/2005

Subjects: Science Essays > Biology

Alcohol Use and Addiction

another statistic in the battle of alcohol use and addiction.Alcohol Use and AddictionAlcohol is a chemical substance made up of the elements carbon, hydrogen, and oxygen. There is more than one alco ... ste (Jones, 1989). Alcoholic beverages usually contain something to lessen the harsh effects of the chemical like a soft drink or some type of fruit juice. The use of alcoholic beverages dates back to ...

(14 pages) 156 2 5.0 Jan/2006

Subjects: Humanities Essays > Health & Medicine > Drugs

"Rachel Carson's Environmental Concern"

f it, so much that she made it her goal to inform the world about the dangers of the pesticides and chemicals that we us in our everyday life. She wanted society as a whole to have a different way of ... e for nature and a career as a marine biologist, she felt we were being threatened by the unnatural chemicals known as pesticides. Her goal was to reach the people by writing in magazine articles and ...

(3 pages) 38 0 3.7 May/2006

Subjects: Literature Research Papers > North American

Chemistry year 11 Syllabus Summary

Module 1: The chemical Earth1. The living and non-living components of the Earth contain mixturesIdentify the diff ... rtually all the rest of the 90 or so elements occur as compounds. This is because most elements are chemically reactive; that is, when they come into contact with certain other elements they react to ... is of little concern.•Although physical properties are important, often other factors such as chemical reactivity (or resistance to corrosion) and cost are significant also. Only a few non-metal ...

(57 pages) 86 0 4.1 Apr/2007

Subjects: Science Essays > Chemistry

The use and abuse of anti-biotics

dication is derived from a bacterium, a fungus, the bark of a tree, and so on. An antibiotic is any chemical substance produced by or derived from a microorganism that has the capacity in dilute solut ... hese came into contact with open wounds. To this end, Josef Lister decided to opt for the effect of chemical antiseptics in preference to physical mechanisms (heat, filtration).Anti-biotics can be the ...

(5 pages) 14 0 0.0 Feb/2008

Subjects: Science Essays > Biology


gular basis and periodically test the equipment for electric shock hazards.Problem 2 ¡V Toxic Chemicals In producing our new product, we need to use a large variety of toxic chemicals (new to ou ... c chemicals (new to our company), that may cause skin irritation or corrosion to the workers. These chemicals are harmless when proper precautions, usually printed on the container, are followed. Howe ...

(3 pages) 689 0 0.0 Feb/2008

Subjects: Social Science Essays > Controversial Issues > Drugs & Alchohol


Alcohol is a chemical substance made up of hydrogen, oxygen, and carbon. Alcohol that we drink can come in three ...

(2 pages) 18 0 0.0 Feb/2008

Subjects: Social Science Essays > Controversial Issues > Drugs & Alchohol

Complete Overview of Year 11 Chemistry

ch can be decomposed into simpler substances, for example into elements.Pure substance = One single chemical. One single formula. One set of physical properties (behaviours).Mixture = two or more pure ... ing GAINS an electron, it is called an ANION.All elements, except most noble gases, tend to undergo chemical reactions and to form compounds in order to obtain the electron configurations of the nearb ...

(20 pages) 22 0 1.0 Sep/2008

Subjects: Science Essays > Chemistry

The Purity and Purification of Solids- Melting Points of Napthalene and Biphenyl

e of purity is achieved as well as 2) a maximum recovery of sample".1 Solubility, the tendency of a substance to dissolve in a liquid, is an important physical property of a substance. An effective re ... ion is highly dependent on differences in solubility at different temperatures. "Most, but not all, substance are more soluble at higher temperatures". 1Crystallization is a delicate procedure that in ...

(3 pages) 20 0 0.0 Nov/2008

Subjects: Science Essays > Chemistry