Notes, abstracts, papers, exams and problems of Chemistry

pure substance: is a phase of uniform composition and unchanging can not be decomposed into other substances of different classes by physical methods.

elements: they are pure substances that can not be decomposed into simpler ones through normal chemical processes.

compounds: they are pure substances made up of two or more elements, which can be decomposed by chemical methods on the elements of which are constituted. A compound always has the same elements and the same proportions regardless of the process followed.

Blended is an aggregation of different substances without causing any chemical reaction between them and therefore may be separated by physical methods.

ponderal laws: they refer to the quantity of matter of different substances... Continue reading "Laws ponderal" »

5. Describe what is electrodeposition, describe the different Experimental methods. Give examples. Advantages and disadvantages. It is the process of production a coating, usually Metallic, on a surface by the action of an electric current._Experimental Methods::-Electroplating: It is a plating process in which metal ions in a Solution are moved by an electric field to coat an electrode. Metallic cations From a solution are reduced on a conductive object (to form a thin layer).-Electrophoretic Deposition:Colloidal particles suspended in a liquid migrate under the Influence of an electric field (electrophoresis) and are deposited onto an Electrode._Advantages: uniform coating thicknen,easy control,high speed of Coating and high pucity._Disadvantages:

Anhydrides:

Non metal + O2 = Systematic Nomenclature / IUPAC (Anhydride)

Acids / Oxoacids:

Acids + H2O = IUPAC (Acid)

Basic Oxoacids:

Metal + O2 = Stock Nomenclature (nº) / IUPAC (Oxide)

Hydroxides:

Basic Oxide + H2O = IUPAC (Hydroxide)

Salts:

Hydroxide + Acid (ic - ate / ous - ite) Fe(OH)2 + HClO = Fe(ClO)2 - Ferrous Hyperchlorite

• Hypo - ous
• - ous
• - ic
• Hyper - ic

Stoichiometry:

Law of Conservation of Mass

Mole:

Amount of Substance that Contains as Many Particles (g)

Molar Mass:

1 mol of --- / g of ----

The environment plays an important role in our lives and people wouldn't be able to live without it. However, we are polluting it every day and it needs to stop. As individuals, we can do lots of things to solve this issue, and this essay will focus on two of them - recycling and the efficient use of energy.

According to recycling, it is the easiest way to see an immediate change and everybody can do it. First, recycling bins are a great method of dividing our waste into paper, plastic, glass, etc., and they can be easily found in every city. Another idea is to reuse the things we have at home and make them new. For example, turning …. 

When it comes to the use of energy, there are many things we can do, especially at home. When we talk about... Continue reading "I choose to live" »

H-hydrogen  2 BE-beryllium    3  B-boron     4 ca-carbon       5n-nytrogen

LI-lithium      MG-magnesium  Ai-aluminium si-silicon         p-phosphorus

na-sodium     CA-calcium        ga-gallium    ge-germanium as-arsenic

CS-cesium      bA-barium        in-indium      se-tin               sb-antimony

FR-francium   RA-radium        ti-thallium      pb-lead            bi-bismuth

6o-oxygen    7 f-fluorine     8 he-hellium        maass(m)   current intensity(iv)

s-sulfur         ci-chlorine        ne-neon          length(l)      surface area(s)

se-selenium  br-bromine      ar-argon         ... Continue reading "What is the time of the pet" »

An ion is an atom which has more or less electrons than protons

Intermolecular forces:force of attraction between covalent molecules,much weaker than covalent bonds within the molecules.DIAMOND:form of pure carbon.Each acrbon atom has four electrons in its outer shell and it therefore formss four civalent bonds.In diamond,each carbon bonds strongly to four other carbon atoms in a tetrahedal arrangement.Diamond has a a very high melting and boiling point.This is because of the very strong carbon-carbon covalent bonds,which extend throughout the whole crystal in three dimensions.A lot of energy has to be supplied to break these strong covalent bonds.All substances with giant covalent structures are solids with high melting and boling points because a lot of energy has to be supplied to break all the strong... Continue reading "A laminar boundary layer is a layer" »

Ductility: Able to undergo change of form without breaking

·Malleability: capable of being shaped, as by Hammering or pressing:

·Density (give an Example): a measurement of how Tightly matter is crammed together. Example: Oil floats on vinegar because Its density is less.

• Chemical properties of matter (give an Example): Are any of the properties Of matter that may only be observed and measured by performing a chemical change or chemical Reaction. Example: oxidation states

·What is a physical Change (give an example): A usually reversible change in the physical 

properties of a substance,as size or shape. Example: When melting an ice cube.

·Difference between Chemical properties and physical properties (give an example)