How to develop your students’ distillation knowledge and practical skills
David Paterson updated this article on 19 June 2026.
The distillation of mixtures to separate and purify substances is an ancient technique, and one that underpins modern society. It produces alcoholic drinks and the fuels that power our vehicles, and even keeps medical scanners working. Distillation is found throughout industry.
The many uses of distillation provide a rich source of stories to frame teaching. For example, the water cycle is effectively a giant distillation cycle and can be linked into many stages of students’ education. Areas of the world without access to fresh water that need to produce potable water provide opportunities for discussing the social and environmental aspects of science.
Society heavily relies on refined products of crude oil, along with substances separated from air by fractional distillation, and this gives context for discussions of distillation’s economic aspects. Useful products from air include nitrogen, oxygen and the noble gases, which are used extensively in medicine, industry and research. For example, liquid nitrogen keeps stored biological samples cool while liquid helium keeps MRI scanners at a cold working temperature, oxygen and argon blow in the basic oxygen steel-making process and krypton lasers produce microelectronics. Steam distillation is also used to purify compounds that are part of many consumer products, including fragrances and foods.
Framing the topic in relevant contemporary contexts helps students appreciate the applicability of a science education for all, not just for those seeking a scientific career.
The distillation of mixtures to separate and purify substances is an ancient technique, and one that underpins modern society. It produces alcoholic drinks and the fuels that power our vehicles, and even keeps medical scanners working (rsc.li/4eFUYUW). Distillation is found throughout industry.
The many uses of distillation provide a rich source of stories to frame teaching. For example, the water cycle is effectively a giant distillation cycle and can be linked into many stages of students’ education. Areas of the world without access to fresh water that need to produce potable water provide opportunities for discussing the social and environmental aspects of science (bit.ly/4eRSDXZ).
Society heavily relies on refined products of crude oil, along with substances separated from air by fractional distillation, and this gives context for discussions of distillation’s economic aspects (rsc.li/4esJfKx). Useful products from air include nitrogen, oxygen and the noble gases, which are used extensively in medicine, industry and research (rsc.li/4vkymjB). For example, liquid nitrogen keeps stored biological samples cool while liquid helium keeps MRI scanners at a cold working temperature, oxygen and argon blow in the basic oxygen steel-making process and krypton lasers produce microelectronics. Steam distillation is also used to purify compounds that are part of many consumer products, including fragrances and foods (rsc.li/3Q8OTbm).
Framing the topic in relevant contemporary contexts helps students appreciate the applicability of a science education for all, not just for those seeking a scientific career.
Progression in ideas and skills
Distillation combines two fundamental physical processes: evaporation and condensation. Students meet these ideas early on and they provide the foundation for progression to fractional distillation:
| Secondary range | Types of learning areas |
|---|---|
|
Pre (approx 7–11) |
|
|
Early (approx 11–14) |
|
|
Mid (approx 14–16) |
|
|
Late (approx 16–19) |
|
Making links between physical state changes and the everyday experiences of students can help them bridge the conceptual divide between the macroscopic world and the abstract sub-microscopic and representational models we are trying to help them build. For example, evaporation can be distinguished from boiling by reference to the drying of puddles. The bathroom mirror after a hot shower is an everyday encounter with condensation. Additionally, you can consolidate the concept of purification using simple investigations, such as Desert survival, that challenges students to recover their last precious water spilled on the sand before they dehydrate.
To fully appreciate many aspects of chemistry, including distillation, students must fully master the particulate nature of matter. Help students to identify their misconceptions around the particle model by continually interrogating their thinking through questioning and asking them articulating their ideas.
Students build a more comprehensive and integrated understanding of the subject, rather than a collection of isolated facts, by making links between concepts in chemistry. For example, one limitation of the particle model is the lack of consideration of forces between particles. This can be discussed in the context of the energetics of distillation, eg why different substances have different boiling points.
Making links between physical state changes and the everyday experiences of students can help them bridge the conceptual divide between the macroscopic world and the abstract sub-microscopic and representational models we are trying to help them build. For example, evaporation can be distinguished from boiling by reference to the drying of puddles. The bathroom mirror after a hot shower is an everyday encounter with condensation. Additionally, you can consolidate the concept of purification using simple investigations, such as Desert survival, that challenges students to recover their last precious water spilled on the sand before they dehydrate (rsc.li/4eir366).
To fully appreciate many aspects of chemistry, including distillation, students must fully master the particulate nature of matter. Help students to identify their misconceptions around the particle model by continually interrogating their thinking through questioning and asking them articulating their ideas (rsc.li/4ew73vL).
Students build a more comprehensive and integrated understanding of the subject, rather than a collection of isolated facts, by making links between concepts in chemistry. For example, one limitation of the particle model is the lack of consideration of forces between particles. This can be discussed in the context of the energetics of distillation, eg why different substances have different boiling points.
Developing practical skills and progression
Practical distillation is commonly found in exam specifications for 14–16 and 16–19 year-old students. Common contexts for 14–16 include producing potable water, and for 16–19 the separation of products during organic synthesis.
Build up to any specified practicals by integrating distillation throughout their practical curriculum. Distillation practicals require accurate observation, measurement and manipulative skills to set up and use the increasingly complex apparatus.
Introduce students aged 7–11 to measuring temperature using both digital and analogue thermometers. Investigate the three phases of water, measuring temperature and how it changes over time. Use activities such as Spacecraft survival to develop your students’ curiosity and problem-solving skills.
For students aged 11–14, carry out simple distillation of copper sulfate solution using side arm boiling tubes, or conical flasks/boiling tubes with the delivery tube passed through a bung. The benefits of a coloured solution are the colourless distillate and the deepening colour of the original solution as the solute becomes more concentrated.
Investigate the purity of water distillate from different angles. For example, use a simple conductivity meter to demonstrate the relative purity of the distillate over the original solution. You could also carry out simple precipitation tests to demonstrate the presence and absence of the copper ions. Boiling point change, between the solution and pure water, can be challenging to demonstrate as the difference is small. A demonstration of the technique is better carried out with saturated sugar–water solution, as the solution has a boiling point of around 110°C. Use a digital thermometer or data-logger to make the elevated temperature clearer for the students. This demonstration has the added benefit of showing the very high solubility of sugar. You can produce sugar crystals from the resulting concentrated sugar solution, linking to crystallisation as example of a separation technique.
Progression of practical skills
Practical distillation is commonly found in exam specifications for 14–16 and 16–19 year-old students. Common contexts for 14–16 include producing potable water, and for 16–19 the separation of products during organic synthesis.
Build up to any specified practicals by integrating distillation throughout their practical curriculum. Distillation practicals require accurate observation, measurement and manipulative skills to set up and use the increasingly complex apparatus (rsc.li/4eyqAeX).
Introduce students aged 7–11 to measuring temperature using both digital and analogue thermometers. Investigate the three phases of water, measuring temperature and how it changes over time. Use activities such as Spacecraft survival to develop your students’ curiosity and problem-solving skills (rsc.li/44nQVYg).
For students aged 11–14, carry out simple distillation of copper sulfate solution using side arm boiling tubes, or conical flasks/boiling tubes with the delivery tube passed through a bung (rsc.li/4oBU8gr). The benefits of a coloured solution are the colourless distillate and the deepening colour of the original solution as the solute becomes more concentrated.
Investigate the purity of water distillate from different angles. For example, use a simple conductivity meter to demonstrate the relative purity of the distillate over the original solution. You could also carry out simple precipitation tests to demonstrate the presence and absence of the copper ions. Boiling point change, between the solution and pure water, can be challenging to demonstrate as the difference is small. A demonstration of the technique is better carried out with saturated sugar–water solution, as the solution has a boiling point of around 110°C. Use a digital thermometer or data-logger to make the elevated temperature clearer for the students. This demonstration has the added benefit of showing the very high solubility of sugar. You can produce sugar crystals from the resulting concentrated sugar solution, linking to crystallisation as example of a separation technique (rsc.li/4oBU9Rn).
While simple distillation is relatively straightforward to set up, reasonable results need patience from students. Some common issues have simple solutions:
| Issue | Solution |
|---|---|
| Fractions distil at the wrong temperature | Position the thermometer bulb in line with the side arm. |
| The mixture boils over into the delivery tube | Fill the boiling tube to a maximum of one third depth (about 5cm3). Add a couple of boiling granules before heating the mixture. Heat gently at first, change to a medium heat and then a roaring flame as necessary. |
| Poor separation of mixture | Heat the mixture gently and consistently by tickling the whole of the liquid volume with a half-blue Bunsen burner flame. |
| Scorching/burning of the clamps | Ensure tubes are clamped at the top and do not overtighten. |
| Little condensation | Wrap the delivery tube in tissue dampened with ice-cold water. Check the seal of the bung is tight. |
| Strong odours emitted from fractions when distilling organic mixtures | Keep the collecting tubes in ice-water and bung as soon as collection is complete. |
Advanced practical distillation
More advanced learners, aged 14–16, can repeat simple distillation to consolidate understanding and skills – for example with a fluorescein solution, which becomes more vividly green as the colourless water distils off. Use synthetic crude oil to carry out a simple fractional distillation. You won’t need a fractionating column for this, as the various components have sufficiently different boiling points (>25°C between the boiling point of each fraction). Equally, classes can distil limonene from orange peel.
As schools are unlikely to have sufficient kit or the desire for under-16s to handle Quickfit glassware, demonstrate distillation using a Liebig condenser. You could also show fractional distillation of synthetic crude oil with a fractionating column as part of a general discussion about different methods for achieving similar outcomes(Figure 2).
At 16–18 years old, students are expected to carry out a simple distillation with QuickFit apparatus (Figure 3). This is usually in the context of purifying products or intermediates in organic synthesis. If the equipment is available, students could also use a fractionating column with a simple mixture, eg propan-1-ol (bp 97°C) and 2-methyl-propan-1-ol (bp 108°C). Additionally, students should have the opportunity to use heating mantles if available. At undergraduate level, aluminium heating blocks (eg DrySyn blocks) on hot plates are the most common heating method. Nowadays, oil baths are rarely used.
More advanced learners, aged 14–16, can repeat simple distillation to consolidate understanding and skills – for example with a fluorescein solution, which becomes more vividly green as the colourless water distils off (rsc.li/43JPG5C). Use synthetic crude oil to carry out a simple fractional distillation (rsc.li/3SeyGly). You won’t need a fractionating column for this, as the various components have sufficiently different boiling points (>25°C between the boiling point of each fraction). Equally, classes can distil limonene from orange peel (rsc.li/4oFLi18).
As schools are unlikely to have sufficient kit or the desire for under-16s to handle Quickfit glassware, demonstrate distillation using a Liebig condenser. You could also show fractional distillation of synthetic crude oil with a fractionating column as part of a general discussion about different methods for achieving similar outcomes(Figure 2).
At 16–18 years old, students are expected to carry out a simple distillation with QuickFit apparatus (Figure 3). This is usually in the context of purifying products or intermediates in organic synthesis (rsc.li/4abfpYp). If the equipment is available, students could also use a fractionating column with a simple mixture, eg propan-1-ol (bp 97°C) and 2-methyl-propan-1-ol (bp 108°C). Additionally, students should have the opportunity to use heating mantles if available. At undergraduate level, aluminium heating blocks (e.g. DrySyn blocks) on hot plates are the most common heating method. Nowadays, oil baths are rarely used.
| Teaching stage | Sequence of Quickfit distillation |
|---|---|
|
Homework |
Prelab videos provide students with an overview of the final setup. |
|
Classwork |
When carrying out dry assembly on the bench, highlight to students the Lego-like construction of a distillation apparatus. |
|
Demo |
Show the full setup of apparatus, including where and how to clamp the flask, and where not to clamp (especially the condenser). |
|
Pair work |
One student sets up the apparatus, while the other assesses setup against an agreed list of criteria. Swap roles once complete and repeat. |
|
Written homework |
Write a standard operating procedure for setting up and carrying out a distillation using Quickfit glassware. |
Many of the ideas in this article will also be useful for other separation techniques, such as evaporation, crystallisation and filtration.
Many of the ideas in this article will also be useful for other separation techniques, such as evaporation, crystallisation and filtration (rsc.li/4gw1oIt).
David Paterson is a chemistry teacher at Aldenham School, Elstree
3 readers' comments