Let's categorize each of the reactions you've provided:
-
2H2O ---> 2H2 + O2
- This is a Decomposition reaction because water (H2O) is breaking down into hydrogen (H2) and oxygen (O2).
-
2C2H6 + 7O2 ----> 4 CO2 + 6H2O
- This is a Combustion reaction because it involves the burning of a hydrocarbon (C2H6, ethane) in the presence of oxygen (O2), producing carbon dioxide (CO2) and water (H2O).
-
2Na + Cl2 ----> 2 NaCl
- This is a Synthesis reaction because sodium (Na) and chlorine gas (Cl2) combine to form sodium chloride (NaCl).
-
4AlBr3 + 3O2 ----> 2 Al2O3 + 6Br2
- This is a Single Replacement reaction because it involves the replacement of bromine with oxygen; however, it more closely resembles a reaction that leads to the formation of products from elemental and compound reactants.
-
KCl + NaI ----> KI + NaCl
- This is a Double Replacement reaction because the potassium (K) and sodium (Na) ions are swapping partners with the chloride (Cl) and iodide (I) ions.
In summary:
- Decomposition (B)
- Combustion (E)
- Synthesis (D)
- Single Replacement (C) or could also be considered Combustion if viewed as a different type based on the context.
- Double Replacement (A)