Answer :
### (a) Outline a Suitable Procedure for Separating a Mixture of X, Y, and Z
Given the solubility information for substances X, Y, and Z:
- [tex]\( X \)[/tex]: Colloidal
- [tex]\( Y \)[/tex]: Soluble in water
- [tex]\( Z \)[/tex]: Insoluble in water
Here is a step-by-step procedure:
1. Dissolution in Water:
- Objective: To dissolve [tex]\( Y \)[/tex] (soluble) in water leaving [tex]\( X \)[/tex] (colloidal) and [tex]\( Z \)[/tex] (insoluble) as a solid mixture.
- Procedure: Add the mixture of [tex]\( X \)[/tex], [tex]\( Y \)[/tex], and [tex]\( Z \)[/tex] to a sufficient amount of water and stir the solution. [tex]\( Y \)[/tex] will dissolve in the water, while [tex]\( X \)[/tex] and [tex]\( Z \)[/tex] remain as a solid phase.
2. Filtration:
- Objective: To separate the insoluble solid [tex]\( Z \)[/tex] and the colloidal [tex]\( X \)[/tex] from the aqueous solution containing [tex]\( Y \)[/tex].
- Procedure: Pass the mixture through a filter paper. The insoluble [tex]\( Z \)[/tex] and colloidal [tex]\( X \)[/tex] will remain as residue on the filter paper, while the solution containing dissolved [tex]\( Y \)[/tex] will pass through as the filtrate.
3. Separation of Colloids:
- Objective: To separate [tex]\( X \)[/tex] (colloidal) from [tex]\( Z \)[/tex] (insoluble).
- Procedure: Centrifugation can be used for this purpose. Pour the residue into a centrifuge tube and spin it at high speed. [tex]\( X \)[/tex] (colloidal particles) will still remain in suspension while [tex]\( Z \)[/tex] will settle at the bottom of the centrifuge tube.
4. Decanting the Colloid:
- Objective: To collect [tex]\( X \)[/tex] colloidal particles separately.
- Procedure: Carefully decant the suspension containing the colloidal [tex]\( X \)[/tex] from the sedimented [tex]\( Z \)[/tex]. [tex]\( X \)[/tex] can further be purified if needed by repeated washing and centrifugation.
In summary, the steps involved are:
- Dissolve [tex]\( Y \)[/tex] in water, leaving [tex]\( X \)[/tex] and [tex]\( Z \)[/tex] as solids.
- Filter to separate [tex]\( Y \)[/tex] (filtrate) from [tex]\( X \)[/tex] and [tex]\( Z \)[/tex] (residue).
- Centrifuge the residue to separate [tex]\( X \)[/tex] (colloidal) from [tex]\( Z \)[/tex] (insoluble).
- Decant to isolate [tex]\( X \)[/tex].
### (b) Definitions
i) An Atom:
- Definition: An atom is the smallest unit of an element that retains the chemical properties of that element. It consists of a nucleus made up of protons and neutrons, surrounded by electrons.
ii) A Molecule:
- Definition: A molecule is a group of two or more atoms that are chemically bonded together. They may consist of the same type of atoms (e.g., [tex]\( O_2 \)[/tex]) or different types of atoms (e.g., [tex]\( H_2O \)[/tex]).
iii) A Gas:
- Definition: A gas is a state of matter characterized by free-moving particles that are not in fixed positions. Gases have no fixed shape and no fixed volume, filling any container they occupy.
iv) Valency:
- Definition: Valency is the measure of an atom's ability to bond with other atoms, typically defined by the number of hydrogen atoms it can combine or displace to form a compound.
v) Chemical Formula:
- Definition: A chemical formula is a symbolic representation of the composition of a compound, indicating the types of atoms and their relative numbers in a molecule. For example, the chemical formula for water is [tex]\( H_2O \)[/tex].
Given the solubility information for substances X, Y, and Z:
- [tex]\( X \)[/tex]: Colloidal
- [tex]\( Y \)[/tex]: Soluble in water
- [tex]\( Z \)[/tex]: Insoluble in water
Here is a step-by-step procedure:
1. Dissolution in Water:
- Objective: To dissolve [tex]\( Y \)[/tex] (soluble) in water leaving [tex]\( X \)[/tex] (colloidal) and [tex]\( Z \)[/tex] (insoluble) as a solid mixture.
- Procedure: Add the mixture of [tex]\( X \)[/tex], [tex]\( Y \)[/tex], and [tex]\( Z \)[/tex] to a sufficient amount of water and stir the solution. [tex]\( Y \)[/tex] will dissolve in the water, while [tex]\( X \)[/tex] and [tex]\( Z \)[/tex] remain as a solid phase.
2. Filtration:
- Objective: To separate the insoluble solid [tex]\( Z \)[/tex] and the colloidal [tex]\( X \)[/tex] from the aqueous solution containing [tex]\( Y \)[/tex].
- Procedure: Pass the mixture through a filter paper. The insoluble [tex]\( Z \)[/tex] and colloidal [tex]\( X \)[/tex] will remain as residue on the filter paper, while the solution containing dissolved [tex]\( Y \)[/tex] will pass through as the filtrate.
3. Separation of Colloids:
- Objective: To separate [tex]\( X \)[/tex] (colloidal) from [tex]\( Z \)[/tex] (insoluble).
- Procedure: Centrifugation can be used for this purpose. Pour the residue into a centrifuge tube and spin it at high speed. [tex]\( X \)[/tex] (colloidal particles) will still remain in suspension while [tex]\( Z \)[/tex] will settle at the bottom of the centrifuge tube.
4. Decanting the Colloid:
- Objective: To collect [tex]\( X \)[/tex] colloidal particles separately.
- Procedure: Carefully decant the suspension containing the colloidal [tex]\( X \)[/tex] from the sedimented [tex]\( Z \)[/tex]. [tex]\( X \)[/tex] can further be purified if needed by repeated washing and centrifugation.
In summary, the steps involved are:
- Dissolve [tex]\( Y \)[/tex] in water, leaving [tex]\( X \)[/tex] and [tex]\( Z \)[/tex] as solids.
- Filter to separate [tex]\( Y \)[/tex] (filtrate) from [tex]\( X \)[/tex] and [tex]\( Z \)[/tex] (residue).
- Centrifuge the residue to separate [tex]\( X \)[/tex] (colloidal) from [tex]\( Z \)[/tex] (insoluble).
- Decant to isolate [tex]\( X \)[/tex].
### (b) Definitions
i) An Atom:
- Definition: An atom is the smallest unit of an element that retains the chemical properties of that element. It consists of a nucleus made up of protons and neutrons, surrounded by electrons.
ii) A Molecule:
- Definition: A molecule is a group of two or more atoms that are chemically bonded together. They may consist of the same type of atoms (e.g., [tex]\( O_2 \)[/tex]) or different types of atoms (e.g., [tex]\( H_2O \)[/tex]).
iii) A Gas:
- Definition: A gas is a state of matter characterized by free-moving particles that are not in fixed positions. Gases have no fixed shape and no fixed volume, filling any container they occupy.
iv) Valency:
- Definition: Valency is the measure of an atom's ability to bond with other atoms, typically defined by the number of hydrogen atoms it can combine or displace to form a compound.
v) Chemical Formula:
- Definition: A chemical formula is a symbolic representation of the composition of a compound, indicating the types of atoms and their relative numbers in a molecule. For example, the chemical formula for water is [tex]\( H_2O \)[/tex].
