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Do all substances dissolve? - Coggle Diagram
Do all substances dissolve?
What is classified as a substances:
Matter containing only one type of atom or molecule, having a constant chemical composition and characteristics
Types of substances
Elements
Eg. Hydrogen, Oxygen, Magnesium
Compounds
Eg. Sulfate, Hydroxide, Ammonia
Meaning of dissolved:
To become or cause to become incorporated into a liquid so as to form a solution.
What can substances be dissolved into:
Substances can be dissolved into solvents to create a homogenous mixture. Examples of solutes include: Water, ethanol, acetone, and benzene
How to know when the substance has stopped dissolving:
The substance should no longer be apparent in the new homogenous solution. If the substance is insoluble, then particles will still be visible and apparent.
Methods used to dissolve substances (when water is a solvent)
Dissociation:
When molecules break down into smaller particles such as ions or atoms
Eg. HCl → H+(aq) + Cl-(aq)
Dispersion:
A process where a mass of solid particles is separated, forming a new connection between the solvent and solute particles
Eg. For milk, liquid fat dispersed in water
Ionisation:
When neutral molecules gain or lose electrons to from ions
Eg. HCl → H2OH+ + Cl
Factors affecting solubility (variables)
Amount of solvent and solute
Increasing the amount of solvent will result in a quicker dissolution as more solvent paritcles will be present to collide, and form secondary bonds with the solute
Temperature of the solution
As the temperature of a solution increases so does its solubility. This is because of collision theory and as more enrgy is present, the particles collide more frequently
State of matter (solid, liquid, gas) of substance and solvent
Liquids are typically the easiest and quickest state of substance that will dissolve. Different methods such as increasing temperature and pressure can fasten the rate of solubility for solids and gasses
Size of solute
A larger solute will take longer to dissolve as there is less surface area compared to its mass. Subsequently, a smaller solute will dissolve much quicker due to its surface area to mass ratio
Polarity of molecules.
Polar substances dissolve in polar substances because of the attraction between positively and negatively charged ions. Non-polar substances dissolve in non-polar substances. This is due to the inability to attract dipoles or ions
Concentration of solute and solvent
As the concentration of either the solute or solvent increases, the rate of dissolution will increase until the solvent is saturated. This is due to collision theory as when there are more particles present, they will collide with one another more frequently compared to if there were less particles
pH of solution
For ionic compounds composing of basic anions, solubility of increases as the pH of the solution decreases as the pH of the solution lowers, the solubility increases. However change in pH does no affect solutions with anions of negligible basicity
Mixing method
Movement and mixing of the solution will increase the rate of dissolution as it causes the solvent and solute particles to move around, thus allowing particles to collide more frequently, forming secondary bonds
Chemistry of how substances dissolve (how are the bonds broken)
Substances are able to dissolve when the intermolecular force of attraction between its particles are weaker than the intermolecular forces of its solvents particles
The process of dissolution involves the breaking of bonds between the solute and the formation of new bonds with the solvents particles.
Methods used to measure the solubility of a substance (dependent variable)
Considering the mass and volume of the solvent (substance) and solute, the solubility can be determined by diving the mass of the solvent (in grams) by the volume (in cubic cm) of the solute then multiplying by 100.
Safety risks
Chemicals:
Contact with or ingestion of chemicals can cause serious harm and could possibly lead to death. To prevent this, all protective equipment should be worn and all chemicals should be disposed of appropriately. If contact or ingestion does occur,
Beakers
Sharp glass from potential broken beakers pose a great safety risk of being cut and potentially infected by the toxic chemicals. To prevent this, all beakers and glass objects should be carefully held and transported, and should not be placed near the edge of a bench or table. In the case that someone is cut, the glass should gently be removed from the wound using sanitised tweezers and the wound should be cleaned with warm water and soap. Gauze should be applied to the cut with pressure and if bleeding persists, a medical practitioner should be called. All broken glass should be disposed of appropriately and into a separate bin
Fire
When around fire, the is always the potential risk for something to burn. To prevent possible harm, an open flame should never be touched and all long hair must be tied back. If one manages to get a burn, the area should be placed under cool running water or a wet compress may be applied. Lotion may be applied to the affected area and bandage should be used. If irritation or pain contiunes, a medical practitioner should be called.
Limitations
Limited Time
Have a restricted allocated time to complete the experiment will not allow for extensive data to be collected and results will be based upon minimal trials
Cost of Chemicals
As many of the chemicals can be expensive, only small amounts can be used to conduct the experiment