chemical changes

• What do metals react with to produce metal oxides?

  Oxygen
• Why are the reactions of metals with oxygen classified as oxidation reactions?

  Because the metals gain oxygen
• What does reduction mean in terms of oxygen?

  Loss of oxygen
• What does oxidation mean in terms of oxygen?

  Gain of oxygen
• How do metal atoms form positive ions during reactions?

  By losing electrons
• What is the reactivity series?

  An arrangement of metals based on their reactivity
• How are metals arranged in the reactivity series?

  Based on their reactions with water and dilute acids
• What happens when a more reactive metal is placed with a less reactive metal in a compound?

  The more reactive metal can displace the less reactive metal
• Where are unreactive metals like gold typically found?

  As the metal itself in the Earth
• How are most metals found in the Earth?

  As compounds that require chemical reactions to extract the metal
• How can metals less reactive than carbon be extracted from their oxides?

  By reduction with carbon
• What does the phrase OIL RIG stand for?

  Oxidation Is Loss and Reduction Is Gain (of electrons)
• What happens to sodium when it is oxidised?

  It loses an electron, resulting in a +1 charge
• What happens to a sodium +1 ion when it is reduced?

  It gains an electron, resulting in a charge of zero
• What must the charges on each side of a chemical equation do?

  Add up to the same number
• What do acids produce when they react with some metals?


  Salts and hydrogen
• What is the general equation for the reaction of acids with metals?

  Acid + metal -> salt + hydrogen
• What type of reactions are acid-metal reactions?

  Redox reactions
• What do alkalis and bases produce when they neutralize acids?

  Salts and water
• What is the general equation for the neutralization of acids by alkalis?

  Acid + alkali -> salt + water
• What do acids react with to produce salts, water, and carbon dioxide?

  Metal carbonates
• What is the general equation for the reaction of acids with metal carbonates?

  Acid + metal carbonate -> salt + water + carbon dioxide
• What does the salt produced in acid-base reactions depend on?

  The acid used and the positive ions in the base, alkali, or carbonate
• What type of salt does hydrochloric acid produce?

  Chlorides (XCl)
• What type of salt does nitric acid produce?

  Nitrates (XNO3)
• What type of salt does sulfuric acid produce?

  Sulfates (XSO4)
• What must the charges on the positive ion from the base/alkali/carbonate and the negative ion from the acid do?

  Add up to zero
• How can soluble salts be made from acids?

  By reacting them with solid insoluble substances
• What are the steps of crystallisation for making soluble salts?

  1. Add solid insoluble substance to the acid until it dissolves.
  2. Stop adding when excess solid sinks to the bottom.
  3. Filter out excess solid, leaving the salt solution.
  4. Evaporate some water, then leave to evaporate slowly.
• What does the pH scale measure?

  The acidity or alkalinity of a solution
• What is the pH of a neutral solution?

  7
• What pH values indicate an acidic solution?

  pH < 7
• What pH values indicate an alkaline solution?

  pH > 7
• What is the purpose of titration in chemistry?

  To measure the volumes of acid and alkali solutions that react with each other
• What characterizes a strong acid in aqueous solution?

  It is completely ionised
• Give examples of strong acids.

  Hydrochloric, nitric, and sulfuric acids
• What characterizes a weak acid in aqueous solution?

  It is only partially ionised
• Give examples of weak acids.

  Ethanoic, citric, and carbonic acids
• How does the strength of an acid relate to its pH?

  The stronger an acid, the lower the pH
• What happens to hydrogen ion concentration as pH decreases by one unit?

  It increases by a factor of 10