SCIENCE 4TH EXAMS

• Chemical Reaction 


  is a process in which one set of new substances called reactants is converted to a new set of substances called products.
• Collision Theory


  when two moving molecules of a substance collide with each other and thus makes a chemical reaction
• Activation Energy


  is involved in breaking some of thee original bonds
• Reaction Mechanism


  the description of the path, or sequence of steps, by which a reaction occurs
• Unimolecular 


  it is termed this way because it involves of only one reactant particle
• Bimolecular


  if the steps involves two reactant particles
• Trimolecular


  involves a collision of three molecules where the rate of the reaction is third order
• Exothermic Reaction


  is a reaction that gives off energy, releases heat, and causes the temperature of the immediate surroundings to rise.
• Endothermic Reaction


  absorbs heat and cools the surroundings.
• Spontaneous Reaction


  a chemical reaction that occurs naturally and continuously once it is started
• Nonspontaneous Reaction


  a reaction that needs a continuous supply of energy for them to proceed
• Law of Conservation of Mass


  This law, also known as the Lomonosov-Levoisier Law, states that the total quantity of mass of substance remains constant regardless of any change that takes place. The mass of the reactants must always be equal to the mass of the p.roducts
• Law of Definite Composition


  This law was first observed by French chemist Louise Proust. Then, after 50 years, Jean Servais Stas experimentally confirmed Proust's observation. It states that the elements combine to form a compound that always contains exactly the same proportion of elements by mass.
• Law of Multiple Proportion


  This law, sometimes called the Dalton's law, after its discoverer. it states that if two elements form more than one compound, the ratios of the masses of the second element combined with a fixed mass of the first elements will be a in a ratio of small whole numbers'
• Chemical Equation 


  Is used to illustrate a chemical reaction using symbols, formulas, and signs.
• Combination or Synthesis Reaction


  two or more substances (either elements or compounds) react to form one product.
• Decomposition or Analysis Reaction


  is a reaction in which a single compound is broken down into two or many smaller compounds or elements.
• Single Replacement Reaction


  an uncombined element displaces an element that is part of a compound
• Double-Replacement Reaction


  atoms or ions from two different compounds replace each other
• Temperature


  is the measure of kinetic energy, or energy of motion, in the particles of a substance.
• Concentration


  It tells us how much solute there is in a solution.
• Catalysts


  is a substance that changes the rate of a chemical reaction by providing an alternate pathway, lowering the activation energy.
• 6 Applications of the Factors Affecting Rate of Reaction

  (Food and pharmaceutical products preservation) (Preservation or decomposition of specimens) (Medication or poison affecting the body) (Dating, restoration, and preservation of artifacts) (Combustion of coals) (Control of fires)