The Physics of Sound essays

The Physics of Sound essays Sound surrounds us at all times. The ring of an alarm clock or the whistle of birds may wake us up in the morning. Through out the day, we hear a variety of sounds; for instance, the banging of pots and pans, the roar of traffic, and the voices of people. When we fall asleep at night, we might listen to the sounds of frogs croaking or the wind whistling. All sounds have one thing in common. This being that the vibrations of an object makes every sound. When an object vibrates, it causes the air around it to vibrate. The vibrations in the air travel out from all directions of the object. They then reach our ears, and the brain reads them as sounds. Many sounds we hear travel through the air; however, they can also travel through solid objects like the earth. Our voice is made in the larynx, which is a part of the throat. Two small pieces of tissue are spread across the larynx. These pieces, called vocal chords, make the opening smaller. Air from he lungs quickly passes trough the tightened chords, causing them to vibrate. The vibrations make the sound of the voice. The tighter the chords are, the faster the vibrations and the higher the resulting sound. If a rock is thrown onto a still pond, several waves travel out from the place where the rock hit the surface. Likewise, sound moves in waves through the air or some other medium. The understanding that sound travels in the form of waves may have originated with the artist Leonardo Da Vinci in 1500. Generally, waves can be spread transversely or longitudinally. In both cases, only the energy of wave motion is spread through medium. No portion of the medium actually moves very far. As the waves caused by the moving object travel outward, they are carried by a medium. This movement causes compression. As the movements move backward it is called rarefractions. Sound requires a medium to travel; therefore, it cannot travel in space, which is a vacuum with no medium. ...

Types of Chemical Reactions (With Examples)

Types of Chemical Reactions (With Examples) A chemical reaction is a process generally characterized by a chemical change in which the starting materials (reactants) are different from the products. Chemical reactions tend to involve the motion of electrons, leading to the formation and breaking of chemical bonds. There are several different types of chemical reactions and more than one way of classifying them. Here are some common reaction types:   Oxidation-Reduction or Redox Reaction In a redox reaction, the oxidation numbers of atoms are changed. Redox reactions may involve the transfer of electrons between chemical species.The reaction that occurs when In which I2 is reduced to I- and S2O32- (thiosulfate anion) is oxidized to S4O62- provides an example of a redox reaction:2 S2O32−(aq) I2(aq) → S4O62−(aq) 2 I−(aq) Direct Combination or Synthesis Reaction In a synthesis reaction, two or more chemical species combine to form a more complex product.A B → ABThe combination of iron and sulfur to form iron (II) sulfide is an example of a synthesis reaction:8 Fe S8 → 8 FeS Chemical Decomposition or Analysis Reaction In a decomposition reaction, a compound is broken into smaller chemical species.AB → A BThe electrolysis of water into oxygen and hydrogen gas is an example of a decomposition reaction:2 H2O → 2 H2 O2 Single Displacement or Substitution Reaction A substitution or single displacement reaction is characterized by one element being displaced from a compound by another element.A BC → AC BAn example of a substitution reaction occurs when zinc combines with hydrochloric acid. The zinc replaces the hydrogen:Zn 2 HCl → ZnCl2 H2 Metathesis or Double Displacement Reaction In a double displacement or metathesis reaction two compounds exchange bonds or ions in order to form different compounds.AB CD → AD CBAn example of a double displacement reaction occurs between sodium chloride and silver nitrate to form sodium nitrate and silver chloride.NaCl(aq) AgNO3(aq) → NaNO3(aq) AgCl(s) Acid-Base Reaction An acid-base reaction is a type of double displacement reaction that occurs between an acid and a base. The H ion in the acid reacts with the OH- ion in the base to form water and an ionic salt:HA BOH → H2O BAThe reaction between hydrobromic acid (HBr) and sodium hydroxide is an example of an acid-base reaction:HBr NaOH → NaBr H2O Combustion A combustion reaction is a type of redox reaction in which a combustible material combines with an oxidizer to form oxidized products and generate heat (exothermic reaction). Usually, in a combustion reaction oxygen combines with another compound to form carbon dioxide and water. An example of a combustion reaction is the burning of naphthalene:C10H8 12 O2 → 10 CO2 4 H2O Isomerization In an isomerization reaction, the structural arrangement of a compound is changed but its net atomic composition remains the same. Hydrolysis Reaction A hydrolysis reaction involves water. The general form for a hydrolysis reaction is:X-(aq) H2O(l) ↔  HX(aq) OH-(aq) The Main Reaction Types There are hundreds or even thousands of types of chemical reactions! If you are asked to name the main 4, 5 or 6 types of  chemical reactions, here is how they are  categorized. The main four types of reactions are direct combination, analysis reaction, single displacement, and double displacement. If youre asked the five main types of reactions, it is these four and then either acid-base or redox (depending who you ask). Keep in mind, a specific chemical reaction may fall into more than one category.