Question

2) Which of the following is a synthesis reaction?

Answer 1

Answer:

The reaction (4) CuO + H₂ → Cu + H₂O is considered as a synthesis reaction because CuO and hydrogen H₂ are reacted to produce Cu and H₂O.

Explanation:

A synthesis reaction occurs when two different atoms or molecules interact to form a different molecule or compound.

The general form for this type of reactions is:

A + B __ AB

A and B are two different chemical substances that combine to form a new product (AB). In a synthesis reaction the chemical bonds between the reagents are broken and new bonds are formed, giving rise to a different compound.

In this case, the reaction CuO + H₂ → Cu + H₂O is considered as a synthesis reaction because CuO and hydrogen H₂ are reacted to produce Cu and H₂O.

On the other side:

• (1) Cu + 2AgNO3 → Cu(NO3)2 + 2Ag

A simple substitution reaction or simple displacement reaction, called single-displacement reaction, is a reaction in which an element of a compound is substituted by another element involved in the reaction. The general form of a simple substitution reaction is:

AB + C __ A +BC

where C and A are pure elements; C replaces A within compound AB to form a new co, placed CB and elementary A.

This is the type of reaction that happens in this case.

• (2) 2Cu +02→ 2CuoO

Combustion reactions are reactions where oxygen intervenes as a reagent. Oxygen has the ability to combine with various elements to produce oxides, where then oxidation is the combination of oxygen with another substance. There are oxidations that are extremely slow, but when oxidation is rapid it is called combustion.

This is the type of reaction that happens in this case.

• (3) CucoO3 → CuO + CO2

In a decomposition reaction, a single substance decomposes, producing two or more different substances. The atoms that form a compound are separated to give the products according to the formula:

AB → A + B

This is the type of reaction that happens in this case.

Answer 2

Answer:

(4) CuO + H₂ → Cu + H₂O.

Explanation:

(1) Cu + 2AgNO₃ → Cu(NO₃)₂ + 2Ag.

It is considered as a single replacement reaction that Cu replaces Ag in its salt AgNO₃.

(2) 2Cu + O ₂ → 2CuO.

It is a combustion reaction that Cu reacts with oxygen results CuO.

(3) CuCO₃ → CuO + CO₂.

It is a decomposition reaction that CuCO₃ is decomposed to CuO and CO₂.

(4) CuO + H₂ → Cu + H₂O.

It is considered as a synthesis reaction that two reactants CuO and hydrogen are reacted to produce Cu and H₂O.

So, the right choice is: (4) CuO + H₂ → Cu + H₂O.