Chemical Reactions: Rates, Equilibrium, and Entropy
Chemistry
Vocabulary
Rate
A ratio between two related quantities expressed in different units.
Reaction Rate
The rate at which the reactants of a chemical reaction form the products.
The calculated average rate can be negative for a reactant or positive for a product.
Collision Theory
States that in order for a collision to be effective, reactant particles must possess a sufficient amount of kinetic energy to break the necessary bonds in the reactants.
There are two things needed for a reaction to occur:
Read MoreUnderstanding Moles and Balancing Chemical Equations
Understanding the Mole Concept in Chemistry
Given the equation above, we can determine the number of moles of reactants and products. A mole represents Avogadro’s number (6.022 x 1023) of molecules. It is similar to a term like “dozen.” If you have a dozen carrots, you have twelve of them. Similarly, if you have a mole of carrots, you have 6.022 x 1023 carrots. In the equation above, there are no numbers in front of the terms, so each coefficient is assumed to be one (1). Thus, you have the same
Read MoreAtomic Theory: A Historical Timeline of Discoveries
Evolution of the Atomic Theory
5th Century BC: Leucippus and Democritus
Leucippus and his pupil Democritus proposed the idea that matter consisted of tiny, indivisible particles called atoms. These ideas were opposed by one of the greatest thinkers of that time, Aristotle. It was only after two millennia that the idea of the atom as a fundamental component of matter was taken up again.
1808: John Dalton’s Atomic Theory
John Dalton proposed the Atomic Theory, which revived and gave scientific value to
Read MoreChemical Equilibrium and Thermodynamics: Key Concepts
States of Aggregation of Matter
- In liquids, as in gases, there is no internal order.
- The change from liquid to gas phase involves a reduction of entropy.
- For a gas mixture, Dalton’s Law states: PA = Pº WxH.
- Avogadro’s Law states that V1N2 = V2N1.
Internal Energy and Enthalpy
- The internal energy change along a constant pressure process is equal to the heat of reaction.
- The variation of enthalpy in a constant pressure process is equal to the heat of reaction at constant volume over P)V.
- The heat brought
Firearm Ammunition: Components and Types
Definition of Bullet
A bullet refers to a spherical or cylindrical, pointed shell, usually made of lead or iron. As a projectile, bullets are part of the ammunition, that is, the supplies needed to operate a firearm.
Description of Bullets
A 9mm Parabellum caliber bullet for firearms has an armored, ogival-cylindrical structure. Its body is composed of a shell, powder, and a percussion cap.
Shell
A cylindrical, metallic container or receptacle that serves as a carrier of the propellant charge (powder)
Read MoreElectrolysis: Understanding Key Concepts and Operating Modes
Electrolysis
Electrolysis applies to a reaction which causes a chemical change when an electric current passes through an electrolyte solution. Oxidation (loss of electrons) takes place at the anode, and reduction (gain of electrons) occurs at the cathode.
Electrode Potential
When a conductor (electrode) is placed in contact with an electrolytic solution, a spontaneous electrical potential difference occurs at the electrode-solution interface. This difference is the electrode potential and is measured
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