How do we use matter?
Define Semipermeable:
a material or substance that is able to allow certain substances to pass through it but not others
Define Osmosis
a process in which molecules of a solvent pass through a semipermeable membrane from a less concentrated solution into a more concentrated one.
Difference between Diffusion and Osmosis
The motion of molecules is through the semipermeable membrane in osmosis whereas, in diffusion, motion is direct and spreads through the liquid, and does not require a semipermeable membrane
Dialysis:
The separation of particles in a liquid by being able to pass through a membrane. (e.g. Osmosis)
Differentiate between miscible and immiscible:
Miscible:
Two liquids that completely dissolve in each other.
(e.g, water and alcohol)
Immiscible:
Two liquids that are not miscible in each other.
(e.g, water and oil)
Define Emulsion:
Emulsion is a mixture of two or more liquids that are normally immiscible, but due to a difference in the liquid (e.g. density), it forms droplets.
Define Emulsifier
Emulsifiers are additives that help two liquids mix. For example, water and oil separate in a glass, but adding an emulsifier will help the liquids mix together.
How does an emulsifier work:
An emulsifier is a substance that stabilizes an emulsion or something that helps mix two immiscible liquids. Emulsifier molecules have 2 ends: a hydrophilic head and a hydrophobic tail. The emulsifier molecule’s hydrophilic head is attracted to the water and sticks to it whereas the hydrophobic tail; is attracted to the fat/oil and sticks to it. When an emulsifier and the 2 immiscible liquids are mixed, then both of the ends stick to their respective liquid, which binds both of the liquids together thus creating a stabilized emulsion.
Emulsifier molecules coat the surface of the immiscible liquid droplets. These coatings keep the droplets evenly dispersed in the water.
Differentiate between Hydrophilic and Hydrophobic:
Hydrophilic:
Liquids that usually mix with or dissolve in water (e.g. Salt)
Hydrophobic:
Liquids that do not mix with water (e.g. Oil)
Define ‘amorphous’, ‘crystalline’, and ‘polycrystalline’
Crystalline:
a crystal that has a structure with repeating or periodic patterns
(e.g, diamonds, quartz, grain of salt.)
Amorphous:
Materials that don’t have a repeating pattern
(e.g, glass or opal)
Polycrystalline:
A combination of small crystalline that may vary in size or orientations
(e.g, common metals, many ceramics, rocks, and ice)
Describe impure substances as either homogeneous or heterogeneous
Homogenous Mixtures:
Homogenous mixtures are when the two different components are distributed uniformly, therefore the composition and properties throughout is constant. Thus, there is only one phase of matter observed at a time. You can’t pick out individual components by simple physical means and can’t see individual chemicals.
Basically the two components are evenly distributed and mixed.
(e.g, Air, water, vinegar, steel)
Heterogeneous Mixtures:
Heterogeneous mixtures are when the two different components aren’t distributed uniformly therefore, they have localized regions with different properties and hence samples are usually not identical in appearance or in behavior. There can be two or more phases of matter in a heterogeneous mixture, where you can pick out individual components by simple physical means and may also distinguish different components in the mixture even if they are in the same state of matter.
Basically the two components are unevenly distributed and both components are visible in its natural state.
(e.g. Cereal in milk, oil, and water)
Pure & Impure Substances
Impure substances would not boil have a plateau at any certain point and thus not remain exactly constant for a while. In contrast, pure substances’ temperature graph will have plateaus and remain constant at its boiling and freezing point.
Define solute, solvent, colloid, gel, and suspension:
Solute:
A substance that will be dissolved
(e.g. sugar is the solute to water)
Solvent
The substance that dissolves the solute to create a solution
(e.g. water is the solvent to sugar)
Colloid:
Solutions in which small particles dissolve into a liquid and don’t settle.
(e.g. milk)
Gel:
A gel is a liquid dissolved in solids with a semi-rigid mixture results.
(e.g. quicksand)
Suspension:
Suspension is a heterogeneous mixture that contains solid particles sufficiently large for sedimentation and settles down. Suspended substances look like they have two or more layers
(e.g, Oil and Water)
Define the terms: filtrate; residue; distillate; volatile;
Distillate:
the liquid that is first evaporated and then, condensed through the Liebig condenser into the final container. It is basically the liquid that passes through the physical changes and through the distillation process. This liquid usually has a lower boiling point as this is usually the first one to be evaporated.
Filtrate:
the liquid that passes through the filter paper during the filtration process.
Residue:
The large particles of an insoluble solid that is left upon the filtrate paper after the filtration process.
Volatility:
A material quality that describes how readily a substance vaporizes. At a given temperature and pressure, a substance with high volatility or a volatile substance is more likely to exist as a vapor. In contrast, a substance with low volatility is more likely to be a liquid or solid. In simple terms, it is how easily the substance evaporates at normal temperatures and pressure.
List & describe the methods of separation (decantation; evaporation; vaporization; filtration; using a separation funnel; distillation; chromatography) the separation of substances through:
Electromagnetism:
This is a fairly simple process in which you use a magnet to pick up magnetic objects. For example, if you have sand and Iron filings, one way to separate both substances is to use a magnet to extract all the iron.
Decantation
The process of the heavy suspended particles sinking to the bottom of the container, this sedimentation occurs for a long time till all the particles are sinking or floating. When all of the particles are sedimented the liquid is then poured out into another container leaving the heavy particles undisturbed.
All in all, decantation can be thought of as pouring a solution out, but only making sure to pour out the lighter liquid. An example is oil and water, in which you make sure to only pour out the oil since it’s lighter than water.
Separation funnel:
Useful equipment to separate two immiscible liquids, you must add both immiscible liquids in the funnel, drain the bottom or less concentrated layer into a beaker. Close the valve before the second liquid reaches the bottom of the funnel. Thus, you have separated the two immiscible liquids since the less dense liquid is in the separating funnel and the denser liquid is collected in the container.
Recrystallization:
A purification technique for solid compounds. To perform recrystallization, an impure solid compound is mixed with hot solvent to form a saturated solution. As this solution cools, the solubility of the compound decreases, and pure crystals grow from solution, leaving the impurities dissolved or vice versa.
Chromatography:
The process of adding a sample on the baseline to a chromatogram and leaving it in water for several hours. This leads to the water rising with the soluble sample along the paper due to the cohesive force of water, this process continues which eventually separates the sample into its different pure components until all of them are distinct and separated.
Distillation:
A process of separating components or liquids of different boiling points by using selective boiling and condensation that creates a distillate. The distillation process is simple. You heat up a liquid until its boiling point, and make the steam of that liquid flow through a Liebig condenser, where it will condense back into its original state into another beaker, thus separating the liquid from another one. An example is ethanol, with a boiling point of 78.37 °C.
Recall the methods for Evaporation and filtration separation of substances
Filtration
When a liquid with insoluble particles travels through filter paper, the insoluble particles rest on the filter paper as filtrate. At the same time, the liquid in the mixture travels through into your beaker.
Evaporation
The process of heating a solution to separate and acquire the solute while the solvent can evaporate. This is the ideal method to acquire a solute when the mixture contains a solvent and a solute specifically due to the solute already being dissolved thus, filtration is no longer feasible.
What is the retardation/retention factor?
The retardation or retention factor is a calculation that indicates how soluble something is, particularly pigments. The smaller the rf value, the more soluble the pigment is.
Calculate the retardation/retention factor for different substances
To calculate the rf value, you take how far the solvent has traveled and divide it by how high the solvent is. In this example, for solvent A and B, the solvent has traveled 0.7cm and 4.1cm (respectively), and the water level stays constant at 4.7cm. Hence to calculate the rf value, you simply do 0.7/4.7 which gives you 0.15,
