When carnallite (KCl⋅MgCl2⋅6H2O) is dissolved in water, it undergoes dissociation, resulting in the formation of ions. The number of ions formed can be determined by examining the individual components of carnallite and their behavior in water.

1. Carnallite Composition:
- Carnallite consists of potassium chloride (KCl), magnesium chloride (MgCl2), and six water molecules (6H2O).

2. Dissociation of Potassium Chloride:
- When KCl is dissolved in water, it dissociates into potassium ions (K+) and chloride ions (Cl-).
- The dissociation equation for KCl is: KCl(s) → K+(aq) + Cl-(aq).

3. Dissociation of Magnesium Chloride:
- Similarly, MgCl2 also dissociates into magnesium ions (Mg2+) and chloride ions (Cl-).
- The dissociation equation for MgCl2 is: MgCl2(s) → Mg2+(aq) + 2Cl-(aq).

4. Water Molecules:
- The water molecules in carnallite do not dissociate. They remain as water molecules (H2O) in the solution.

5. Calculation of Ions:
- From the dissociation equations, we can determine that one molecule of KCl produces one potassium ion (K+) and one chloride ion (Cl-).
- One molecule of MgCl2 produces one magnesium ion (Mg2+) and two chloride ions (Cl-).

- Since carnallite contains one molecule of KCl and one molecule of MgCl2, it will produce the following ions:
- One potassium ion (K+)
- One magnesium ion (Mg2+)
- Three chloride ions (3Cl-)
- Additionally, the six water molecules (6H2O) remain as water molecules in the solution and do not dissociate into ions.

6. Total Number of Ions:
- Adding up the ions formed from KCl and MgCl2, we get:
- One potassium ion (K+)
- One magnesium ion (Mg2+)
- Three chloride ions (3Cl-)

- Hence, when carnallite is dissolved in water, a total of five ions are formed.

Note: It is important to remember that the presence of water molecules in the formula does not contribute to the formation of ions. Only the potassium chloride and magnesium chloride components dissociate to form ions in the solution.