elements, compunds and mixtures

• Rate of reaction is the speed at which a reaction happens
• Rate is the change in a quantity divided by time
• Quantity can be the mass or volume of reactant used or product formed
• An experiment example is reacting hydrochloric acid and sodium thiosulfate to measure rate
• Another experiment is measuring the volume of gas produced using a gas syringe
• Factors that increase the rate of reaction:

  • Increasing concentration of reactants in solution
  • Increasing pressure of gas reactants
  • Increasing surface area of solid reactants (crushing into a powder)
  • Increasing temperature
• Adding a catalyst increases the rate by reducing activation energy needed
• Reversible reactions can go back to original reactants once products are made
• Le Chatelier's principle states that a system at equilibrium will adjust to counteract changes
• Increasing pressure favors the forward reaction in a closed system
• Increasing temperature favors the endothermic reaction
• Organic compounds have carbon forming the backbone of molecules
• Crude oil consists mostly of hydrocarbons (carbon and hydrogen atoms)
• Alkanes are chains of single covalently bonded carbon atoms with hydrogen atoms
• General formula for alkanes: CNH2N+2
• Fractional distillation separates crude oil into different length alkanes
• Longer alkanes have higher boiling points due to stronger intermolecular forces
• Different fractions of crude oil are used for various purposes like fuel and plastics
• Polymers can be made from alkenes, not alkanes
• Alkenes have a carbon-carbon double bond and are unsaturated
• Cracking breaks longer alkanes into shorter alkanes and alkenes
• Alcohols have an -OH functional group at the end of their names
• Alcohols can combust with oxygen to produce carbon dioxide and water
• Short alcohols can mix with water to produce a solution
• Oxidizing alcohols without combustion produces carboxylic acids
• Polymers are long-chain alkanes made from repeating monomers
• Polymerization of alkenes creates polymers like polyethene
• Condensation polymerization joins monomers with two functional groups to make polymers
• Amino acids are the building blocks of proteins
• Amino acids can be polymerized to make polypeptides
• DNA is made from nucleotides and stores genetic code
• Starch is a natural polymer made from repeating units
• DNA is made from two polymers that spiral around each other in a double helix
• DNA is made from four different monomers called nucleotides
• Starch is a natural polymer with glucose as the monomer
• Cellulose is a polymer made from beta glucose
• Proteins have amino acids as their monomers
• Obtaining pure substances is important in chemistry
• Testing the melting point or boiling point of a substance can determine if it is pure
• A formulation is a mixture designed for a specific purpose with specific quantities of substances