Chemestry

Chemestry

1. Chemical Ecuations

   • *catalyst increase the speed of reaction and it does not consume during the process. *balance

2. Mixtures and solutions

   • *In a solution the solute can be ions or molecules
   • Molarity
   • Disolve
     • The stock solution just give the necessary amount of mols of solute. 
   • Molar solubility
     • The maximum amount of  solute that can be dissolve in an volume of solvent.
     • insaturated, satured, sobresatured
       • There is the maximun amount of solute possible in solution. If you add more it wont dissolve. 
     • Kps
       • The kps is alike to the product of the ions cons concentration each one elevated to their steichiometry coeficient. The concentration is S=Molar solubility.

3. Aqueous solution and precipitation

   • *Ever the relation between the ion compounds reactives will be the next AB+CD->AD+BC Where AD will be solid, so the precipitation, to define it i use the table which is solid a which aqueous. Is important that the reaction ever will have that estructure, cations and anions change of couple.
   • Electrolytes
     • *When a substances become in ions when it is disolved, this substance is an electrolyte. *While more ions make, stonger electrolyte it will be. *Acids are electrolyte cause form ions when they dissolve in water. *If the compound after of been dissolve do not make a solution that conducts the electricity, this is a nonelectrolyte substance. *The compounds with ionic bounds are electrolytes
   • Precipitation
     • *This is the solid product of the reaction between two electrolytes. If you have AB and CD, and both are electrolytes, the reaction between them will product two kind of molecules, AC and BD, one of them like a solid and the other dissolved in water. It is insoluble.
     • Net ionic equation
       • It shows the reaction in terms of ions, taking out the spectators ions, (those which do not change). Just show the precipitation product in terms of ions (like the reactives)
     • Prepare new solutions
       • AB+CD-->AC+BD If the reactives are electrolytes,  then AC will be solid insoluble and BD aqueous.  According with some rules of Solubility i can know which will be AB precipitation 

4. Redox reactions

   • Occurs a redox reactions when the elements of the reactive change of state of oxidation.
   • Oxidation
     • The element that oxidized is the reducing agent
   • Reduction
     • The element that reduced itself, is the oxidizing agent
   • Balancing
     • *Ionic net reaction: The amount of electrons lost in oxidizing has to be the same amount of amount of electrons get in the reduction.
     • How
       • I make the semireactions of oxidization and reduction and i multipli for entire numbers to the semireactions to have the same amount of electrons lost and electrons got. After i cancelate the electrons and sum the semireactions.
   • Does the reaction happen?
     • E
       • reduction potential I make the semireactions and i ubicate them in the table, to get their respective E.The element that will reduce is that which has a higher potential reduction  In the case of the oxidation i change the sign of the numbre of E.The E total will be the sum of both semi reactions. If that sum is negative the reaction will not occur. If it is positive the reaction will  happen.

5. Acid-base Neutralization

6. Stoichiometry

   • Mass to mass and mole to mole predictions
   • Titration
     • Volumetric analysis This allows to know the concentration of any substance from the reaction with a second. 
     • Reaction Redox
       • This is when the susbtances what i want to study is not neither a base nor solution. You make that the element or substance which you want theamount in substance reacts, reduce or oxide. Then i add my second substance with a known molarity until it reacts. After i get out the amount of moles that i spent and make the relation from the original theory reaction. 
     • Base - Acid
   • percent of Performance
     • Percent: 100*real grams/theorical grams
   • Limit reactive

7. Bonds

   • The elements get or loss electrons to get the electronic configuration of the noble gas nearer.
   • Ionic
     • *The most electronegativity element take one or more electrons from de lower electronegativiy element *To know if any ionic compound has or has not strength bond,while smaller be their radii and have high charges (positive or negative) the bond will be stronger.This kind of bond usually occurs between elements with a high electronegativity (anion) and elements with low electronegativity. So between elements of the first and second group, and elements of the seven group.
     • First energy of ionization
     • Electron afinity
     • Properties
       • -Crystaline structures -High melting point -brittle  -The strong of the bond is higher if the cation and anion are smaller and have hight charges.
   • Covalent
     • *Here the elements involved SHARE pairs of electrons. *This bond occurs generally between nonmetallics elements *In the Lewis structure a line like - represents two electrons.
   • Lewis structure
     • --- a pair of electrons being sharing ´´ a lone pair This produces repultion, even more that a bond (---) *Here it is not problem the shape of molecule, it just shows the bonds and lone pairs.
     • Rules
       • EVER *All the atoms achieve eight electrons of balance * Each element has to done eight electrons oF valence COUNT THE TOTAL VALENCE ELECTRONS IN THE MOLECULE A poliatomic anion has MORE electrons *If the molecule is neutra each atom has to achieve that with its own valence electrons. If the molecule is an anion i can put more electrons.*ALL the valance electrons has a couple, so it is an bond pair or it is a lone pair*Count the amount of electrons overall. You have to use ALL of them.*The center atom is that with lower electronegativity.
     • Resonance
       • HERE, THE ATOMS KEEPS THEIR POSITION, JUST CHANGE THE KIND OF BOND! When a formula can be interpreted like more than one lewis structure. You have to show all resonance of each fromula.All the resonances of a formula are called "resonance hybrid" conform for the kekules (structures)*the resonance put the lower energy to the moleculeEach hybrid is difference chemically
       • Change just bonds
     • Formal charge
       • It is calculated for each atom in the structure, while i get numbers nearer to cero, the estructure is better. FC=V-(L+1/2S) FC: formal charge V: original electrons of valence L: amount of electrons in lone pairs S:amount of electrons been sharing. This is to get the lowerst charge in the molecule.
       • Atoms ubication
   • Exceptions to the octet rule
     • When the total amount of electrons in odd
     • Radicals
       • Species with odd amount of electrons
     • Biradicals
       • Species with 2 odd amount of electrons

8. VSEPR

   • H2O
     • Angular  No muestra angulo
   • Lineal
     • 180°
   • Trigonal plana
     • 120°
   • Amoniaco
     • Piramidal trigonal No ángulo
   • Metano
     • Tetrahédrico 109.5°