Chemical Changes

• What do metals produce when they react with oxygen?

  Metal oxides
• Why are the reactions of metals with oxygen called oxidation reactions?

  Because metals gain oxygen
• What do metal atoms form when they react with other substances?

  Positive ions
• How is the reactivity of a metal related to its positive ion formation?

  Higher reactivity means easier positive ion formation
• What metals are included in the reactivity series?

  • Potassium
  • Sodium
  • Lithium
  • Calcium
  • Magnesium
  • Zinc
  • Iron
  • Copper
• What happens when a more reactive metal is present in a compound?

  It can displace a less reactive metal
• What is the limitation of reactions of metals with water and acids?

  They are limited to room temperature
• How are unreactive metals like gold found in the Earth?

  As the metal itself an ore in fact.
• How can metals less reactive than carbon be extracted?

  By reduction with carbon
• What does reduction involve in terms of oxygen?

  The loss of oxygen
• What is a Redox Reaction?

  A reaction where oxidation and reduction occurs.
• What is oxidation in terms of electrons?

  The loss of electrons
• What do acids produce when they react with metals?

  Salts and hydrogen
• What type of reactions are acid-metal reactions?

  Redox reactions
• Which metals should students focus on regarding reactions with acids?

  Magnesium, zinc, and iron
• What do acids neutralize to produce salts and water?

  Alkalis and bases
• What does hydrochloric acid produce when it reacts?

  Chlorides
• What is the process to make soluble salts from acids?

  Reacting acids with solid insoluble substances
• What happens to the excess solid when making soluble salts?

  It is filtered off
• What is the first step in making pure, dry samples of soluble salts?

  Add solid to the acid
• What do acids produce in aqueous solutions?

  Hydrogen ions (H⁺)
• What do alkalis produce in aqueous solutions?

  Hydroxide ions (OH^-)
• What does the pH scale measure?

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

  7
• What happens in neutralization reactions?

  Hydrogen ions react with hydroxide ions
• What is a strong acid's behavior in aqueous solution?

  They break up completely to produce a high concentration of hydrogen ions.
• How does the strength of an acid relate to pH?

  Stronger acids have lower pH
• What happens to hydrogen ion concentration as pH decreases?

  It increases by a factor of 10
• What is the process of electrolysis?

  Electrolysis involves using electricity to break down electrolytes to form elements.
• What happens to ions during electrolysis?

  They move to the electrodes
• What is produced at the cathode during electrolysis of molten ionic compounds?

  The metal
• What is produced at the anode during electrolysis of molten ionic compounds?

  The non-metal
• Why is electrolysis used for extracting metals?

  If the metal is too reactive
• Why must the positive electrode be continually replaced in electrolysis?

  The oxygen reacts with the carbon in the electrodes, forming carbon dioxide which gradually burns off. Carbon is therefore lost from the positive electrodes, so they must be replaced frequently.
• What determines the ions discharged during electrolysis of aqueous solutions?

  The relative reactivity of the elements
• What is produced at the cathode if the metal is more reactive than hydrogen?

  Hydrogen
• What is produced at the anode unless halide ions are present?

  Oxygen
• What are the key steps in the electrolysis of aqueous solutions?

  1. Ions move to electrodes
  2. Discharge occurs at electrodes
  3. Products depend on reactivity
• What is the purpose of investigating electrolysis with inert electrodes?

  To observe the reactions occurring and to avoid any unwanted chemical reactions with the electrodes
• What is an Alkali?

  a substance with a pH greater than 7 that forms OH- ions in a solution