What is formed at the anode and cathode when the following solutions are electrolysed?

sodium iodide
copper II chloride
sodium sulphate
NaOH
HCl
magnesium nitrate

also is this true: if the metal in the compound is higher in the reactivity series than hydrogen then hydrogen is produced instead of the metal at the positive electrode. but shouldnt it be the negative electrode at the cathode because the H plus ions are attracted to the opposite charges??? im not sure what the phrase means??

http://en.wikipedia.org/wiki/Electrolysis

To determine what is formed at the anode and cathode during electrolysis, we need to look at the ions present in each solution and their respective standard electrode potentials.

In general, during electrolysis, positive ions (cations) are attracted to the negative electrode (cathode) where reduction occurs, while negative ions (anions) are attracted to the positive electrode (anode) where oxidation occurs. The specific reactions at each electrode depend on the nature of the ions present and their standard electrode potentials.

Let's analyze each solution:

1. Sodium Iodide (NaI):
At the cathode (negative electrode): Sodium ions (Na+) are reduced to form sodium metal (Na) because it is in the reactivity series above hydrogen.
At the anode (positive electrode): Iodide ions (I-) are oxidized to form iodine (I2) gas.

2. Copper II Chloride (CuCl2):
At the cathode: Copper(II) ions (Cu2+) are reduced to form copper metal (Cu) because it is less reactive than hydrogen.
At the anode: Chloride ions (Cl-) are oxidized to form chlorine (Cl2) gas.

3. Sodium Sulphate (Na2SO4):
At the cathode: Hydrogen ions (H+) are reduced to form hydrogen gas (H2) because it is less reactive than sodium.
At the anode: Hydroxide ions (OH-) are oxidized to form oxygen gas (O2) and water (H2O).

4. Sodium Hydroxide (NaOH):
At the cathode: Hydrogen ions (H+) are reduced to form hydrogen gas (H2) because it is less reactive than sodium.
At the anode: Hydroxide ions (OH-) are oxidized to form oxygen gas (O2) and water (H2O).

5. Hydrochloric Acid (HCl):
At the cathode: Hydrogen ions (H+) are reduced to form hydrogen gas (H2) because it is less reactive than hydrogen.
At the anode: Chloride ions (Cl-) are oxidized to form chlorine (Cl2) gas.

6. Magnesium Nitrate (Mg(NO3)2):
At the cathode: Magnesium ions (Mg2+) are reduced to form magnesium metal (Mg) because it is less reactive than hydrogen.
At the anode: Nitrate ions (NO3-) are oxidized to form oxygen gas (O2) and nitrogen dioxide gas (NO2).

Regarding your question about the phrase "if the metal in the compound is higher in the reactivity series than hydrogen then hydrogen is produced instead of the metal at the positive electrode," you are correct that it refers to the cathode, which is the negative electrode. The phrase means that when the metal in the compound being electrolyzed is higher in the reactivity series than hydrogen, then hydrogen gas will be produced at the cathode instead of the metal. This is because hydrogen ions (H+) are more easily reduced than metal ions with higher reactivity.

Remember that during electrolysis, positive ions are attracted to the negative electrode (cathode), and negative ions are attracted to the positive electrode (anode). Oxidation occurs at the anode, and reduction occurs at the cathode.