𐙚˙⋆.˚ ᡣ𐭩 chapter 11 𐙚˙⋆.˚ ᡣ𐭩

• Oxidation

  The addition of oxygen to a substance
• Rusting of iron


  Iron reacts with oxygen and water to form rust, a reddish-brown flaky solid
• Respiration


  1. Glucose is broken down in the presence of oxygen to provide cells with energy

  2. Carbon dioxide and water are produced
• Differences between oxidation and combustion

  • For combustion, heat must be given out
  • For oxidation, heat may or may not be given out
• Similarities between oxidation and combustion

  Both reactions involve reacting with oxygen
• All combustion reactions are oxidation reactions but not all oxidation reactions are combustion reactions
• Combustion is a chemical reaction in which a substance is heated in the presence of oxygen (one of the reactants)
• In combustion, heat and light are usually given out
• Thermal decomposition is the process in which a substance breaks down into 2 or more simpler substances when heated
• When metal carbonates are heated, they usually decompose to from the metal oxide and carbon dioxide as products
• Decomposition is the process in which a substance breaks down into two or more simpler substances without being heated.
• A neutralisation reaction occurs between an acid and a base
• Acids can be identified by their sour taste and ability to turn blue litmus paper red
• In word equations, reactants are written on the left hand of the arrow and the right hand side of the arrow, and conditions are written on the arrow.
• During a chemical reaction, the atoms of the products are always obtained from the reactants, and atoms of products rearrange themselves and combine chemically
• The law of conservation of mass states that atoms cannot be created nor destroyed during a chemical reaction
• In a chemical reaction, atoms are not created nor destroyed, they are only rearranged
• Bonds break in a chemical reaction, as atoms rearrange themselves and new bonds are formed in products
• total number of each type of atom in reactants = total number of each type of atom in products.
• The law of conservation of mass states that mass is conserved in a chemical reaction (no atoms are created or destroyed)
• Overcoming oxidation in real life:

  The use of salt water helps to minimise the amount of oxygen available for oxidation, and lemon juice helps to slow down the action of chemical substances that cause browning of the food.
• Antioxidants are man-made or natural substances that may prevent or delay some types of cell damage.
• Food rich in antioxidants: dark chocolate, pecans, blueberries, strawberries, artichokes (veggies), goji berries, kale, red cabbage and beans
• Physical change: A process where matter changes form but does not produce any new substance. The composition of the original material remains unchanged.
• Chemical change: A process where one or more new substances are produced from existing ones. The composition of the original materials has changed.
• neutral: neither acidic nor alkaline
• alkalis: blue litmus paper remains blue & red litmus paper turns blue
• pH scale: measures how acidic or alkaline something is
• Acidity increases as pH decreases
• pH scale is used to measure how acidic or basic a solution is. It ranges from 0 - 14 with 7 being neutral.
• Acidic solutions have pH values less than 7, while alkaline solutions have pH values greater than 7.
• Acids:

  turns blue litmus paper red and red litmus paper remains red

  reacts with alkalis, metals and carbonates
• Alkalis:

  turns red litmus paper blue and blue litmus paper remains blue

  reacts with acids in neutralisation reactions