Lecture 7 Flashcards
What happens when magnesium burns?
Magnesium burns in air with a white flame.
Magnesium Oxidation formula?
2Mg+ 02 = 2MgO
Magnesium is oxidised because it loses electrons and increases in oxidisation state from 0 to +2. Oxygen is reduced because it gains electrons and decreases in oxidation state from 0 to -2.
What happens when hydrogen is passed over heated copper oxide?
The black compound turns pink
Write the Reduction Formula for copper oxide reacting with hydrogen?
CuO + H2 = Cu + H2O
What happens when calcium burns in air?
Calcium burns in air with a red flame and forms the white compound calcium oxide.
Write the formula for calcium reacting with oxygen
2Ca + O2 = 2CaO
What is a oxidizing agent?
A substance that gains electrons and is thereby reduced to a low valency state.
What is a reducing agent?
A substance that loses electrons and is thereby oxidized to a higher valency state.
What is the formula and half equations of sodium reacting with chlorine?
2Na + Cl2 = 2NaCl
Na = Na+ + e-
Cl2 + 2e- = 2Cl-
What is an oxidation number?
A number given to each atom or ion in a compound that shows us its degree of oxidation. It can be +,- or 0.
What is hydrogens usual oxidation state in compounds?
+1
What is sodium and other group 1 metals usual oxidation state in compounds?
+1
What is calcium and group 2 metals usual oxidation state in compounds?
+2
What is Aluminium usual oxidation state in compounds?
+3
What is chlorine and group 7 metals usual oxidation state in compounds?
-1
What is oxygen usual oxidation state in compounds?
-2
Why does fluorine show a -1 oxidation number?
Fluorine is the most electronegative halogen, meaning it has strong attraction for electrons. When fluorine chemically bonds to another element, it pulls the shared electrons towards itself, creating a partial negative charge.
Why is fluorine an excellent oxidizing agent?
It can easily accept electrons to achieve a stable electron configuration.
Difference between oxidation state and oxidation number?
Oxidation state refers to the actual charge of an atom however oxidation number is the hypothetical charge assigned to an atom due to a set of rules.
What are the applications of redox reactions ?
Battery- used for generating DC current. Storage cells are used in vehicles to supply all the electrical needs.
Combustion- explosions
Photosynthesis- conversion of water and C02 into carbohydrates.
Production of chemicals based on electrolysis such as chlorine.
Sanitising water and bleaching materials.
Electroplating
