In the spontaneous reaction between gold ions and silver metal, the reducing agent is

• gold ions

• silver metal

• silver ions

• gold metal

Metal A is more reactive than metal B. Which statement is correct?

• Electrons flow in the external circuit from B to A

• Positive ions flow through salt bridge from A to B
• Positive ions flow in external circuit from B to A.
• Electrons flow through salt bridge from B to A

Answer explanation

A more reactive metal means it is a stronger reducing agent, so it is oxidized, so it is at the anode.

Tags

NGSS.HS-PS1-2

Reduction happens at the 

• anode
• cathode
• salt bridge
• voltmeter

Answer explanation

Reactions in voltaic cells are

• spontaneous, redox reactions
• non-spontaneous, redox reactions
• spontaneous, non-redox reactions
• non-spontaneous, non-redox reactions

This electrode in a voltaic cell gains mass

• anode
• cathode

Answer explanation

Cats are fat, gain mass.

Ants are skinny, lose mass.

What reaction occurs at the anode?

• Ag⁺ + e^- →Ag
• Ag → Ag⁺ + e^-
• Ni²⁺ + 2e^- → Ni
• Ni → Ni²⁺ + 2e^-

Tags

NGSS.HS-PS1-2

Which of the following represents oxidation?

• C → CH₄

• Fe³⁺ → Fe²⁺

• Cl₂ → 2Cl^-

• Zn → ZnO

Answer explanation

Oxidation involves the loss of electrons or an increase in oxidation state. In the reaction Zn → ZnO, zinc (Zn) is oxidized to zinc oxide (ZnO), indicating it has lost electrons, thus representing oxidation.

Tags

NGSS.HS-PS1-1

NGSS.HS-PS1-2

Which of the following half reactions correctly represents a reduction half reaction?

• Fe →Fe²⁺ + 2e^-

• Pb⁴⁺ + 2e^- →Pb²⁺

• 2O^2- →O₂ + 4e^-

• Fe + 3e^- →Fe³⁺

Answer explanation

The reduction half reaction involves gaining electrons. In the correct choice, Pb⁴⁺ + 2e^- → Pb²⁺, lead ions gain 2 electrons, reducing Pb⁴⁺ to Pb²⁺. The iron equation has the electrons on the wrong side so it isn't balanced correctly.

Tags

NGSS.HS-PS1-1

NGSS.HS-PS1-2

Is it Spontaneous? Aluminum metal reacts with aluminum ions.

• Spontaneous

• Non Spontaneous

Answer explanation

Same height so OA not above RA, non- spontaneous.

Tags

NGSS.HS-PS1-1

NGSS.HS-PS1-2

Is it Spontaneous? Lithium metal reacts with sodium ions.

• Spontaneous

• Non Spontaneous

Answer explanation

OA above RA, downhill, spontaneous.

Tags

NGSS.HS-PS1-4

NGSS.HS-PS3-4