Question

1. choose the best answer.

what type of single replacement reaction is taking place in the following equation?
cu + hno₃ → cu(no₃)₂ + h₂
○ the replacement of hydrogen in an acid by a metal
○ the replacement of a metal cation by another metal
○ the replacement of a halogen by another halogen
○ the replacement of hydrogen in water by a metal

1. choose all that apply.

which two skeleton or balanced equations represent a synthesis reaction?
□ mg(s) + cu(no₃)₂(l) → mg(no₃)₂(aq) + cu(s)
□ kcl + o₂ → kclo₃
□ ba(clo₃)₂ → bacl₂ + o₂
□ 3h₂(g) + n₂(g) → 2nh₃(g)

Explanation:

Question 1

Step1: Analyze the reaction type

The reaction is $\ce{Cu + HNO_{3} -> Cu(NO_{3})_{2} + H_{2}}$. In this reaction, copper (a metal) reacts with nitric acid (an acid), and hydrogen in the acid is replaced by copper to form hydrogen gas.

Step2: Evaluate each option

• Option 1: "the replacement of hydrogen in an acid by a metal" matches the reaction as Cu (metal) replaces H in $\ce{HNO_{3}}$ (acid).
• Option 2: There is no metal cation being replaced (the cation here would be related to a metal - but the reaction is with H in acid, not a metal cation replacement).
• Option 3: There are no halogens involved in the reaction, so this is incorrect.
• Option 4: The acid here is $\ce{HNO_{3}}$, not water, so this is incorrect.

A synthesis reaction is a reaction where two or more substances combine to form a single product (A + B -> AB).

• Reaction 1: $\ce{Mg(s) + Cu(NO_{3})_{2}(l) -> Mg(NO_{3})_{2}(aq) + Cu(s)}$ is a single - replacement reaction, not synthesis.
• Reaction 2: $\ce{KCl + O_{2} -> KClO_{3}}$: Two substances (KCl and $\ce{O_{2}}$) combine to form $\ce{KClO_{3}}$, so it is a synthesis reaction.
• Reaction 3: $\ce{Ba(ClO_{3})_{2} -> BaCl_{2} + O_{2}}$ is a decomposition reaction (one substance breaks into two or more).
• Reaction 4: $\ce{3H_{2}(g) + N_{2}(g) -> 2NH_{3}(g)}$: Two substances ($\ce{H_{2}}$ and $\ce{N_{2}}$) combine to form $\ce{NH_{3}}$, so it is a synthesis reaction.

Answer:

the replacement of hydrogen in an acid by a metal

Question 2