1) Answer is: BaO + CO2 → BaCO3.
Synthesis reaction is a type of reaction in which multiple reactants (in this example barium oxide and carbon dioxide) combine to form a single product (in this example barium carbonate).
New substance, barium carbonate is formed, with different chemical and physical properties than reactants (barium oxide and carbon dioxide).
CH4 + O2 → CO2 + H2O is combustion reaction.
FeCO3 → FeO + CO2 and 2NH3 → 2N2 + 3H2 are decomposition reaction.
2) Answer is: Synthesis reactions are the opposite of decomposition reactions.
Decomposition is reaction where one substance is broken down into two or more simpler substances.
For example, electrolysis of water is the decomposition reaction, because from one molecule (water) two molecules (hydrogen and oxygen) are produced.
Water is separated into two molecules: 2H₂O → 2H₂ + O₂.
Synthesis of water: 2H₂ + O₂ → 2H₂O.
3) Answer is: Three molecules of N2 should be produced during the decomposition.
Balanced chemical reaction: 2NaN₃ → 2Na + 3N₂.
This is decomposition reaction, because from one molecule (sodium nitride) two new substances (sodium and nitrogen) are produced.
According to principle of mass conservation, number of atoms must be equal on both side of chemical reaction.
4) Answer is: 2NH3(g) → N2(g) + 3H2(g).
This is decomposition reaction, because from one pure substance (in this example ammonia) two new pure substances (hydrogen and nitrogen) are produced.
According to principle of mass conservation, number of atoms must be equal on both side of chemical reaction.
There are two nitrogen and six hydrogen atoms on both side of balanced chemical reaction.
5) Answer is: False.
The general form of synthesis reaction is: A + B → AB
, where A and B are elements or compounds and AB is a compound.
In synthesis reaction, it can be pure elements or pure chemical compounds on the left side of chemical reaction.
For example, balanced chemical reaction: CaO(s) + H₂O(l) → Ca(OH)₂(aq).
6) Answer is: False.
This is example of single displacement reaction.
Single displacement is reaction where neutral element metal or nonmetal (in this example potassium) become an ion as it replaces another ion (in this example hydrogen) in a compound.
Potassium lose electron and change oxidation number from 0 to +1 (oxidation) and hydrogen gain electron and change oxidation number from +1 to 0 (reduction).
