Positive and negative rods
Copper is positive. Zinc is negative.
Which rod is which
In a copper and zinc cell, one rod is the positive electrode and the other is the negative electrode.
What do you think decides which metal is the positive one?
What this lesson covers
The idea
A Voltaic cell uses a pair of different metals; because of their chemical properties, some metals such as copper act as positive electrodes while others such as zinc act as negative electrodes.
Which rod is which
In a copper and zinc cell, one rod is the positive electrode and the other is the negative electrode.
What do you think decides which metal is the positive one?
- Its chemical properties
- Its size
- Which rod was put in first
Pair the metals
Pick copper on one side and zinc on the other. Look at the signs on the rods. Then swap the sides.
The metal decides
Copper showed + and zinc showed −. It did not matter which side each was on. Their chemical properties decide. Other common pairs are zinc and silver, aluminium and copper, iron and copper, magnesium and copper, and lead and copper.
A Voltaic cell uses a pair of different metals. Because of their chemical properties, some metals like copper act as positive electrodes, and others like zinc act as negative electrodes.
- Metal | Electrode
- Copper | Positive
- Zinc | Negative
Notes
In a Voltaic cell, some metals like copper act as positive electrodes and others like zinc act as negative electrodes, because of their chemical properties.
Check yourself
In a copper and zinc cell, copper is the …
Which metal acts as the negative electrode?
Why is copper the positive electrode and zinc the negative one?
Which pair of metals is commonly used in a Voltaic cell?
- positive electrode — correct. Yes!
- negative electrode. Zinc is the negative electrode.
- electrolyte. The electrolyte is the liquid. Copper is a rod, the positive electrode.
- Copper. Copper acts as the positive electrode.
- Zinc — correct. Yes!
- The salt solution. The salt solution is the electrolyte. It is not a metal rod.
- Because copper is heavier. Weight does not decide it. Their chemical properties do.
- Because copper is on the left side. The side does not matter. Their chemical properties decide.
- Because of their chemical properties — correct. Yes!
- Zinc and copper — correct. Yes!
- Copper and copper. The two metals must be different.
- Zinc and zinc. The two metals must be different.