C4 - chemical changes

• How are metals listed according to their reactivity?

  From most reactive at the top to least reactive at the bottom
• What extraction method is needed for metals above carbon?

  Electrolysis
• How can metals below carbon be extracted?

  By reduction
• Why are silver, gold, and copper generally found in the earth as pure ores?

  Because they are very unreactive and do not react with anything
• What do most metals react with in the earth?

  Oxygen, forming metal oxides
• What gas is produced during electrolysis if the metal is more reactive than hydrogen?

  Hydrogen gas
• What happens when magnesium chloride reacts with calcium?

  Calcium displaces magnesium, forming calcium chloride and magnesium
• What occurs when magnesium chloride reacts with aluminum?

  No reaction occurs because magnesium is more reactive than aluminum
• What does oxidation refer to in a redox reaction?

  Loss of electrons
• What does reduction refer to in a redox reaction?

  Gain of electrons
• What is the positive electrode called in electrolysis?

  Anode
• What is the negative electrode called in electrolysis?

  Cathode
• What must half equations in electrolysis reflect?

  The movement of electrons and must be balanced
• How do you balance the half equation for copper reduction?

  Add two electrons to balance the charge
• What is the first step in balancing the half equation for fluorine oxidation?

  Balance the fluorine atoms
• What is produced when an acid reacts with a metal?

  A salt and hydrogen gas
• What do you get when a metal oxide reacts with an acid?

  A salt and water
• What is produced when an acid reacts with a metal hydroxide?

  A salt and water
• What do you get when an acid reacts with a metal carbonate?

  A salt, water, and carbon dioxide
• What is the neutralization equation?

  Hydrogen ions plus hydroxide ions produce water
• What is the first step in carrying out a titration?

  Pipette 25 cm³ of an alkali into a conical flask
• What indicates the endpoint of a titration?

  The first permanent color change
• What color does phenolphthalein turn in an alkali?

  Bright pink
• What color does methyl orange turn in an acid?

  Bright red
• What is the relationship between moles of acid and moles of alkali at neutralization?

  They are equal in a one-to-one ratio
• How do you calculate the number of moles of acid used in a titration?

  Concentration times volume of the acid
• What is the formula to find concentration from moles and volume?

  Concentration = moles / volume
• What is the difference between strength and concentration of acids?

  Strength refers to full dissociation, while concentration refers to the amount of acid in a solution
• Name a strong acid.

  Hydrochloric acid (HCl)
• What happens to strong acids in solution?

  They fully dissociate into ions
• What is required for a compound to conduct electricity?

  It must be molten or dissolved
• What is the role of cryolite in aluminum electrolysis?

  To reduce the melting point of molten aluminum oxide
• What happens at the negative cathode during aluminum electrolysis?

  Positive aluminum ions gain electrons and form aluminum atoms
• What happens at the positive anode during aluminum electrolysis?

  Negative oxygen ions lose electrons and form oxygen gas
• What is produced when oxygen gas reacts with the carbon electrode?

  Carbon dioxide
• What are the common setups for electrolysis?

  Sodium chloride, sodium sulfate, copper chloride, and copper sulfate
• What are the products of electrolysis of sodium chloride?

  Hydrogen gas, chlorine gas, and sodium hydroxide
• What is the test for hydrogen gas?

  A squeaky pop sound
• What is the test for oxygen gas?

  Relighting a glowing splint
• What is the test for chlorine gas?

  It bleaches damp litmus paper