Understanding Chemical Reactions and Stoichiometry

Mol is the quantity of a substance defined by Avogadro's constant, which indicates the number of particles, such as atoms, molecules, and ions. One mole equals 6022 particles.
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Reaction Types:
a) The reorganization of atoms:
1) Synthesis Reaction: Two substances combine to create a new form.
Example: 2 %IMAGE_2% + %IMAGE_3% -> 2 %IMAGE_4%
2) Decomposition Reactions: A substance is broken down into simpler components.
Example: %IMAGE_5% -> %IMAGE_6%
3) Single Displacement Reactions: An element replaces another in a compound.
Example: 2Al + 6 HCl -> 2 %IMAGE_7%
4) Double Displacement Reactions: The positions of two substances are exchanged.
Example: Ca %IMAGE_8% -> %IMAGE_9%

a) The Reaction Mechanism:
1) Acid-Base Reactions:
* Acids: These can be binary or complex and always start with H. Acids dissolve in water, generating hydrogen ions. For example, lemon juice, HCl, etc.
* Bases: Hydroxide bases also dissolve in water, generating hydroxide ions. For example, NaOH.
* Neutralization: An acid and a base react to form salt and water. For example, HBr + LiOH -> H2O + LiBr.
pH: A liter of water has a pH of 7, which is neutral.
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And H %IMAGE_14% O %IMAGE_15% There. pH = log %IMAGE_16%

1) Precipitation Reaction: Two solutions are mixed to obtain insoluble products.
S: solid / L: liquid / g: gas / aq: aqueous solution.
2) Oxidation-Reduction Reactions:
The reaction involves the loss of electrons (oxidation) by one element and the gain of electrons (reduction) by another.
Example: Sn -> Sn + HCl -> Sn: loss of electrons / H: gain of electrons.
3) Combustion Reactions: Substances react with oxygen, releasing CO2 and water.
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Stoichiometric Calculations:
1) Calculate the Mass: Use the formula: mass = n (O at 0°C and 760 mmHg).
2) Calculate the Volume:
a) 1 mol occupies 22.4 L.
b) Use the formula: %IMAGE_19%

Endothermic Reactions: Energy is absorbed as heat. The reaction is positive, indicating heat flow into the system.
Exothermic Reactions: Energy is released as heat. The reaction enthalpy is negative, indicating heat flow out of the system.
Reaction Enthalpy: This is the heat released or absorbed at constant pressure during a chemical reaction.