Substances From The Earth Part3 Flashcards
(49 cards)
Describe the reaction of magnesium with oxygen.
• 2Mg(s) + 02(g) → 2MgO(s)
• Magnesium gains oxygen (oxidised), and oxygen loses oxygen (reduced).
• Magnesium is the reducing agent, and oxygen is the oxidising agent.
Describe the reaction of lead (Il) oxide with carbon.
• 2PbO(s) + C(s) → 2Pb(s) + CO2(g)
• Lead (II) oxide loses oxygen (reduced), and carbon gains oxygen (oxidised).
• Carbon is the reducing agent, and lead (Il) oxide is the oxidising agent.
Describe the reaction where hydrogen is added to ethene.
• C2Ha(g) + H2(g) → C2H6(g)
• Ethene (C2H4) gains hydrogen to form ethane (CHs), so it is reduced.
• Ethene is the oxidising agent, and hydrogen is the reducing agent.
Describe the reaction where hydrogen is removed from hydrogen sulfide.
•H2S(g) + Cl(g) → S(s) + 2HCl(g)
• Hydrogen sulfide (HS) loses hydrogen and is oxidised to sulfur (S).
• Hydrogen sulfide is the reducing agent, and chlorine is the oxidisin agent as it gains hydrogen.
How do you identify the oxidising and reducing agents when hydrogen is involved?
• Oxidising agent: The substance that gains hydrogen and is reduced.
• Reducing agent: The substance that loses hydrogen and is oxidised.
What happens in the reaction C2H4(g) +
H2(g) → C2Hь(g)?
.
• Ethene (CHa) gains hydrogen and becomes ethane (CHo), so it is reduced.
• Ethene is the oxidising agent, and hydrogen is the reducing agent.
What happens in the reaction HeS(g) +
C|(g) → S(s) + 2HC|(g)?
• Hydrogen sulfide (HS) loses hydrogen and is oxidised to sulfur (S).
• Hydrogen sulfide is the reducing agent, and chlorine is the oxidising agent as it gains hydrogen.
How can redox reactions be interpreted in terms of electron transfer?
• Oxidation: The process of losing electrons.
• Reduction: The process of gaining electrons.
• Oxidising agent: The electron acceptor.
• Reducing agent: The electron donor.
What happens in the reaction 2Mg(s) +
02(g) → 2MgO(s)?
• Magnesium (Mg): Loses electrons to form
Mg? ions, so it is oxidised.
• 2Mg → 2Mg2++ 4e
• Oxygen (02): Gains electrons to form O- ions, so it is reduced.
• 02+4e → 202-
• Magnesium is the reducing agent because it donates electrons.
• Oxygen is the oxidising agent because it accepts electrons.
What happens in the reaction 2Na(s) +
C|(g) → 2NaCl(s)?
• Sodium (Na): Loses electrons to form Na* ions, so it is oxidised.
• 2Na → 2Nat + 2e-
• Chlorine (Clz): Gains electrons to form Clions, so it is reduced.
• Cla + 2e* → 2Cl
Sodium is the reducing agent because it
donates electrons.
Chlorine is the oxidising agent because it
accepts electrons.
What is the oxidation number of elements in their free state?
• All elements in the free state (uncombined with any other elements) have an oxidation number of zero.
• Examples: Fe(s), Na(s), S(s), C(s), C/(g).
What is the oxidation number of simple ions?
• The oxidation number of a simple ion is the same as the charge on the ion.
• Examples: Na* (oxidation number +1), CI-(oxidation number -1).
Flashcard 45: Oxidation
What is the oxidation number of simple ions?
• The oxidation number of a simple ion is the same as the charge on the ion.
• Examples: Na* (oxidation number +1), CI-(oxidation number -1).
Flashcard 45: Oxidation
What are the oxidation numbers of Group 1, 2, and 3 metal ions?
• Group 1: +1 (e.g., Na, K).
• Group 2: +2 (e.g., Ca?, Mgz).
• Group 3: +3 (e.g., Als+).
What is the oxidation number of Group 7 non-metal ions?
• Group 7: -1 (e.g., Cl, Br).
What is the oxidation number of hydrogen in different compounds?
• +1 when combined with non-metals (e.g., hydrogen chloride, HCI).
• -1 when combined with metals (e.g., sodium hydride, NaH).
What is the oxidation number of the oxide ion (O2-)?
• The oxidation number of the oxide ion is always -2.
How is the oxidation number of a polyatomic ion determined?
• The oxidation number of a polyatomic ion is the same size and sign of the charge of the polyatomic ion.
• Example: The sulfate ion (SO,?*) has an oxidation number of -2.
How do oxidation and reduction occur in the reaction 2Na(s) + C|(g) → 2NaCl(s)?
• Electron transfer:
• Sodium loses electrons to form Nations:
2Na → 2Na* + 2e (oxidation).
• Chlorine gains electrons to form Clions: Cla
+ 2e → 2Cl (reduction).
• Oxidation numbers:
• Sodium changes from O to +1 (oxidation).
• Chlorine changes from O to -1 (reduction).
What happens when coke burns with oxygen in the blast furnace?
• The coke (carbon) reacts with oxygen to produce carbon dioxide:
• C(s) + 02(g) → COz(g).
• In this reaction, carbon is oxidised (it gains oxygen).
How do oxidation numbers change in the reaction between iron ore and carbon monoxide in the blast furnace?
• In Fe203 + 3CO → 2Fe + 3C02:
• Iron: The oxidation number decreases from +3 (in FezO3) to 0 (in Fe), so iron is reduced.
• Carbon: The oxidation number increases from +2 (in CO) to +4 (in COz), so carbon is oxidised.
What is a net ionic equation?
A net ionic equation represents the actual chemical reaction that occurs in a solution, showing only the ions and compounds that are involved in the reaction. Spectator ions, which do not take part in the reaction, are not included in the net ionic equation.
What are spectator ions in a net ionic equation?
Spectator ions are ions that remain unchanged during the reaction. They are present in the solution but do not participate in the chemical change, so they are not included in the net ionic equation.
What happens when NaCl dissolves in
• NaCl dissociates in water into Na* and Cl- ions.
• lonic Equation:
NaCl (s) → Na†(ag) + Cl (aq)
