Chemical changes

• What happens to metals in oxidation reactions?

  They gain oxygen
• What is the reaction between metals and oxygen called?

  Oxidation reaction
• What is the definition of reduction?

  Loss of oxygen
• What is the definition of oxidation?

  Gain of oxygen
• What is the reactivity series?

  Arrangement of metals in order of reactivity
• How is the reactivity of a metal related to its tendency to form positive ions?

  Reactivity is related to tendency to form positive ions
• What are the reactions of potassium, sodium, lithium, calcium, magnesium, zinc, iron, and copper with water and dilute acids?

  • Potassium: violent reaction with water
  • Sodium: very quick reaction with water
  • Lithium: quick reaction with water
  • Calcium: more slow reaction with water
  • Magnesium: quick reaction with dilute acid
  • Zinc: fairly slow reaction with dilute acid
  • Iron: more slow reaction with dilute acid
  • Copper: very slow reaction with dilute acid
• What can a more reactive metal do to a less reactive metal in a compound?

  Displace the less reactive metal
• Why is gold found in the Earth as the metal itself?

  Because it is very unreactive
• How can metals less reactive than carbon be extracted from their oxides?

  By reduction with carbon
• What involves the loss of oxygen?

  Reduction
• What does the phrase OIL RIG stand for?

  Oxidation Is Loss and Reduction Is Gain
• How do you write an ionic equation for reduction?

  The metal gains electrons and loses a positive charge
• How do you write an ionic equation for oxidation?

  The metal loses electrons and gains a positive charge
• How do you determine which element has been oxidized and which has been reduced in an equation?

  By looking at the gain or loss of electrons
• What are the steps to determine which element has been oxidized and which has been reduced in an equation?

  1. Identify the elements involved in the reaction
  2. Determine the change in charge for each element
  3. Identify the element that has lost electrons (oxidized) and the element that has gained electrons (reduced)
• What type of reaction occurs when acids react with metals?

  Redox reaction
• What is the general equation for the reaction between an acid and a metal?

  Acid + metal -> salt + hydrogen
• What is the rule used to determine which substance is oxidized and which is reduced in a redox reaction?

  OIL RIG
• What are the steps to determine which substance is oxidized and which is reduced in a redox reaction?

  1. Identify the substances involved in the reaction
  2. Determine the electrons gained and lost by each substance
  3. Apply the OIL RIG rule: Oxidation Is Loss, Reduction Is Gain
• What is the ionic equation for the reaction between magnesium and hydrochloric acid?

  Mg -> Mg2+ + 2e-, 2H+ + 2e- -> H2
• Why is the reaction between magnesium and hydrochloric acid a redox reaction?

  Because magnesium is oxidized and hydrogen is reduced
• What is the general equation for the neutralization of an acid by an alkali or base?

  Acid + alkali/base -> salt + water
• What are the products of the neutralization reaction between an acid and a metal carbonate?

  • Salt
  • Water
  • Carbon dioxide
• What is the relationship between the charges on the positive ion from the base/alkali/carbonate and the negative ion from the acid in a neutralization reaction?

  The charges must add up to zero
• How is the salt produced in a neutralization reaction determined?

  By the acid used and the positive ions in the base/alkali/carbonate
• What are the ions produced by acids and alkalis in aqueous solutions?

  • Acids: H+ ions
  • Alkalis: OH- ions
• What is the pH scale used to measure?

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


  7
• What is the ionic equation for any neutralization reaction?

  H+(aq) + OH-(aq) -> H2O(l)
• What are the steps to carry out a titration?

  1. Wash the burette with dilute hydrochloric acid and water
  2. Fill the burette with acid to 100cm3
  3. Use a pipette to add 25cm3 of alkali to a conical flask
  4. Add a few drops of a suitable indicator to the conical flask
  5. Add acid from the burette to the alkali until the end-point is reached
  6. Record the volume of acid used
  7. Repeat the experiment to gain more precise results
• What is the titre in a titration?

  Volume of acid needed to exactly neutralize the alkali
• How is the concentration of a substance calculated in a titration?

  Using the formula: concentration = moles / volume
• What is the difference between a strong acid and a weak acid?

  • Strong acid: completely ionized in aqueous solution
  • Weak acid: partially ionized in aqueous solution
• What is the relationship between the pH of a solution and the concentration of H+ ions?

  As pH decreases by one unit, H+ concentration increases by a factor of 10
• What is a strong acid?

  Completely ionized in aqueous solution
• What is a weak acid?

  Partially ionized in aqueous solution
• What is the difference between concentrated and dilute solutions?

  • Concentrated solution: large amount of substance in a given volume
  • Dilute solution: small amount of substance in a given volume
• Why is it important to use a suitable indicator in a titration?

  To determine the end-point of the reaction
• What happens to ions when an ionic substance is melted or dissolved?

  They are free to move