1. Introduction to Separation Science
How do we separate the seemingly inseparable?
Your cell phone is mainly made of plastics and metals. It’s easy to appreciate the process by which those elements add up to something so useful. But there’s another story we don’t hear about -- how did we get our raw ingredients in the first place, from the chaotic tangle of materials that is nature? Iddo Magen uncovers the answer in a group of clever hacks known as separation techniques.
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Separation science is a study of various methods to separate mixtures. We do so in order to obtain pure substances.
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These separation methods are physical methods as they do not involve any chemical change. No new substance is formed.
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Substances in a mixture are separated according to their physical properties, such as:
Physical Property
Type of Separation
Magnetism
Size
Boiling Point
Ability to sublime
Solubility
Use of magnet/electromagnet
Solid-solid
Filtration, reverse osmosis, decanting
Solid-liquid
Distillation, fractional distillation, desalination
Sublimation
Separating funnel, crystallisation,
chromatography
Liquid-Liquid
2. Solid-Liquid Separation
Tutorial - Filtration
Filtration is used to separate an insoluble solid from a mixture.
In this video, we will cover
1. When filtration is used
2. How to carry out filtration
3. Applications of filtration
Application of filtration – The Drinkable Book
The Drinkable Book is a life saving tool that filters water. Once water is passed through the filter, bacteria count is reduced by over 99.99%, making the filtered water comparable to tap water in the United States of America.
This filter paper will revolutionise water purification. It costs only pennies to produce, making it by far the cheapest option on the market. Each filter is capable of giving someone up to 30 days worth of clean water, and each book is capable of providing someone with clean water for up to 4 years.
Tutorial - Evaporation to Dryness
Evaporation to dryness is used to obtain a soluble solid from a solution by heating the solution until all the solvent has boiled off. Evaporation to dryness is not suitable if the substance decomposes on strong heating (e.g. sugar) or if you want to obtain a crystalline solid (e.g. copper(II) sulfate crystals)
In this video, we will cover:
1. When evaporation to dryness is used
2. How to carry out evaporation to dryness
3. Applications of evaporation to dryness
Tutorial - Crystallisation
Crystallisation is the process of obtaining pure solid sample (soluble solid) from its solution. The solution is first heated to a point of saturation. When the solution is cooled, the solubility of the substance decreases, causing the formation of crystal deposits.
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In this video, we will cover:
1. When crystallisation is used
2. How to carry out crystallisation
3. Applications of crystallisation
Incredible Egg Geode
You too can create beautiful crystals at home through the technique of crystallization! The principle behind crystallisation is the difference in solubility of a substance at different temperatures. A solution needs to be saturated before crystals will form.
Borax Crystal Star
Bringing real snowflakes inside individually is next to impossible. So, to work around this conundrum, we've come up with the Magic Crystal Snowflake. This special snowflake is just a beautiful and unique as a snowflake from the sky, but it won't melt! The Magic Crystal Snowflake uses some fun hands-on chemistry and makes a perfect holiday experiment.
3. Solid-Solid Separation
Tutorial - Magnetic Attraction
A magnet can be used to separate a magnetic substance from a non-magnetic substance. Some magnetic substances include iron, nickel, cobalt and steel. For example, we can separate iron from a mixture of iron (metal) and sulfur (non-metal) using a magnet.
In this video, we will cover:
1. When magnetic attraction is used
2. How to carry out a separation using magnetic attraction
Tutorial - Sublimation
Sublimation is used to separate a solid that sublimes from one that does not. Sublimation is the process where a solid substance undergoes the transition from the solid state to the gaseous state directly, without passing through the liquid state. Some substances such as ammonium chloride, dry ice and iodine sublime on heating.
In this video, we will cover:
1. When sublimation is used
2. How to carry out sublimation
4. Liquid-liquid Separation (Immiscible)
Tutorial - Separating Funnel
A separating funnel can be used to separate immiscible liquids.
In this video, we will cover:
1. When a separating funnel is used
2.. How to carry out a separation using a separating funnel
5. Liquid-liquid Separation (Miscible)
Distillation for Survival
Watch how to obtain portable water using a portable distiller that anyone can make.
Simple Distillation
This video provides an overview of how to carry out simple distillation.
Why must water enter from the bottom of the condenser?
To ensure that the water jacket is completely filled with water to cool the vapours efficiently and condense the vapour into a liquid.
Steam Distillation for Essential Oils (Enrichment)
Steam distillation is a special type of distillation (a separation process) for temperature sensitive materials like natural aromatic compounds.
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Steam distillation is employed in the isolation of essential oils, for use in perfumes, for example. In this method, steam is passed through the plant material containing the desired oils. Eucalyptus oil and orange oil are obtained by this method on the industrial scale.
6. Desalination
Desalination is the removal of dissolved salts from seawater to obtain pure drinking water.
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Distillation is one way we can desalinate but it is very expensive, as it requires lots of energy.
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Another more popular desalination method is reverse osmosis. It is used to obtain fresh drinking water from seawater.
Desalination by Distillation
Singapore's future water security lies with desalination and reuse. These rainfall-independent sources of water will help to reduce our vulnerability to weather uncertainties. Tuas Desalination Plant, Singapore's third desalination plant boost our desalination capacity up from 100mgd to 130mgd. Desalination can now meet up to 30% of Singapore's current water demand. Watch this video to find out how we treat sea water into potable drinking water at Tuas Desalination Plant.
Desalination by Reverse Osmosis
Desalination is Singapore's 4th national tap. At the SingSpring desalination plant in Tuas (opened in 2005), sea water goes through a pre-treatment process where suspended particles are removed. In the second stage, the water undergoes reverse osmosis (RO). This is the same technology used in the production of NEWater. The water produced is very pure and is remineralised in the third stage. After treatment, desalinated water is blended with treated water before it is supplied to homes and industries in the western part of Singapore.
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Today, desalinated water can meet up to 25% of Singapore’s current water demand.
7. Chromatography
Experiments you can do at home!
Tutorial – Paper Chromatography
At the end of this video, you will be able to describe how to carry out a paper chromatography experiment and understand the rationale for the various precautions we take while doing paper chromatography.
We will be separating inks obtained from different coloured markers.
How the Secret Service Uses Ink to Solve Crimes
You may have an image of the Secret Service—suits, sunglasses and earpieces. But, there’s an entire forensics arm of the agency dedicated to solving crimes—sometimes using nothing more than an ink blot. The lab tackles some of the toughest frauds and forgeries, armed with the world’s largest collection of pens, inks and printer cartridges. By comparing prints to a library that includes over 12,000 samples of black ink, this team of experts is able to solve cases from forged checks and counterfeit money to written threats.
8. Testing for Purity
Melting Point Determination
Determining the melting point of a substance is the best way to determine its purity. A pure substance would have an exact and constant melting point while the presence of impurities lower the melting point of a substance.
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This video shows an instrument used to determine the melting point of a sample.