Electrolysis Quiz

The two rods placed in the substance being electrolysed are called the:

• electrodes

• cells

• electrolytes

• wires

Answer explanation

The two rods in electrolysis are called electrodes. They facilitate the flow of electric current through the electrolyte, allowing the chemical reactions necessary for electrolysis to occur.

The positive electrode:

• attracts positive ions which lose electrons

• attracts positive ions which gain electrons

• attracts negative ions which gain electrons

• attracts negative ions which lose electrons

Answer explanation

The positive electrode attracts negative ions, which are electron-rich. When these negative ions reach the positive electrode, they lose electrons, thus neutralizing their charge.

Which statement is true?

• electrolysis works best if the electrolyte is a solid.

• electrolysis only works when the electrodes are made to touch, completing the electrical circuit.

• electrolysis only works if the electrolyte contains ions which are free to move, so the electrolyte must be either molten or in solution.

• electrolysis only works when the electrolyte is an insulator.

Answer explanation

Electrolysis requires an electrolyte with free-moving ions, which is only possible in molten or solution form. Solid electrolytes do not allow ion movement, making the other statements incorrect.

Substances being electrolysed must have which type of bonding?

• ionic

• it really doesn't matter

• metallic

• covalent

Answer explanation

Substances being electrolysed must have ionic bonding because ionic compounds dissociate into ions in solution, allowing them to conduct electricity. Other types of bonding, like covalent or metallic, do not facilitate this process.

Predict the products when molten magnesium bromide is electrolysed.

• magnesium metal and solid bromine

• magnesium metal and bromine gas

• hydrogen gas and bromide ions

• magnesium ions and chlorine gas

Answer explanation

During the electrolysis of molten magnesium bromide, magnesium ions are reduced to form magnesium metal at the cathode, while bromide ions are oxidized to produce bromine gas at the anode. Thus, the products are magnesium metal and bromine gas.

What is an electrolyte?

• A molten compound or solution that is to be broken down by electrolysis

• The metal/graphite rods used in an electrolysis experiment

• The process of breaking a compound into elements using direct electric current

Answer explanation

An electrolyte is a substance that, when molten or dissolved in solution, can conduct electricity and is broken down by electrolysis. This makes the first choice correct, as it accurately describes the nature of an electrolyte.

What is a cathode?

• A negatively charged electrode

• A positively charged electrode

Answer explanation

A cathode is defined as a negatively charged electrode, where reduction occurs in electrochemical cells. This distinguishes it from an anode, which is positively charged.

In the electrolysis of molten sodium chloride, what is the product at the cathode?

• Sodium

• Hydrogen

• Chlorine

Answer explanation

In the electrolysis of molten sodium chloride, sodium ions are reduced at the cathode to form sodium metal. Therefore, the product at the cathode is sodium.

What is the anode?

• The positively charged electrode

• The negatively charged electrode

Answer explanation

The anode is defined as the positively charged electrode in an electrochemical cell. It attracts negatively charged ions, making it essential for the flow of current.

What does the term electrolysis mean?

• Breaking a mixture into its constituent elements using a direct electric current

• A positive ion

• Breaking a compound into its constituent elements using a direct electric current

• Breaking a compound into its constituent elements using an alternating electric current

Answer explanation

Electrolysis specifically refers to breaking a compound into its constituent elements using a direct electric current. This distinguishes it from breaking mixtures or using alternating current.