Particulate Model of Solutions
Chemistry: IB Diploma Higher Level, topic 1.9.2
Particulate Model of Solutions
Representing solutions in terms of their particles can be used to illustrate the structure, properties and interactions of a solution.
Acidic solutions
- Acids are characterized by their ability to donate protons.
- In solution, acidic solutions have more H3O+ than OH-.
- The more H3O+ relative to OH-, the stronger the acidic solution.
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Dissolved salts
- Dissolved salts can be represented in terms of their separated ions in solution.
- The ratio of cations to anions must match the molecular formula of the salt.
- In this case, Ca(OH)2 has twice as many OH- ions as Ca2+ ions.
Hydrogen bonding
- Particulate representations can be used to show the position of intermolecular forces.
- Hydrogen bonds form between the single lone pair of electrons on N or one of the two lone pairs on O and a H atom.
Hydrated ions
- Water reorganizes around ions in solution so that opposite charges come into contact.
- Here, water's partially negative O is attracted to Na+ and the partially positive H atoms are attracted to Cl-.
Conducting electricity
- Conducting electricity requires the movement of charge.
- In this case, only the Ca(OH)2 can conduct as it has charged particles.
- When dissolved in water, NH3 forms NH4+ and can then conduct electricity.
Test yourself on Particulate Model of Solutions
The van’t Hoff factor is defined as the ratio of solute particles in solution to the number of formula units dissolved.
Using the above definition to help you, estimate the van’t Hoff factor for 1.0M Mg(OH)2.The van’t Hoff factor is defined as the ratio of solute particles in solution to the number of formula units dissolved.
Using the above definition to help you, estimate the van’t Hoff factor for 1.0M HCl.