Uploaded March 2024 | Updated September 2026, 20 hours ago
In this video, we look at how aldehydes can be oxidised to carboxylic acids using the acidified dichromate (VI) ion. We explore the colour change that takes place and how we can use this reaction to distinguish between aldehydes and ketones.
In this video, we look at how aldehydes can be oxidised to carboxylic acids using the acidified dichromate (VI) ion. We explore the colour change that takes place and how we can use this reaction to distinguish between aldehydes and ketones.

![GCSE Chemistry Revision Alpha Scattering Experiment
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In this video, we look at the alpha scattering experiment. First we look at what the ancient Greeks thought about the structure of atoms and how this was disproven by the discovery of the electron. We then explore an early model of atomic structure called the plum pudding model. Next we look at the alpha scattering experiment. We explore how the alpha scattering experiment was carried out including why gold foil was used. We then look at how the results of the alpha scattering experiment told scientists that atoms are mainly empty space, with a central positive nucleus containing most of the mass of the atom and electrons around the edge. Finally, we look at how scientists replaced the plum pudding model with the nuclear model of atomic structure.
This video is based on the AQA spec. This video may be appropriate for iGCSE / O Level Chemistry. Please consult your specification. The Amazon link above is an affiliate link. This provides a small commission which helps to support freesciencelessons. The cost remains the same to you. If you prefer not to use this, you can search Amazon for the Freesciencelessons workbooks.
Image credits:
Democritus (By Original uploader was Odysses - Museo archeologico nazionale di Napoli, CC BY-SA 3.0, https://commons.wikimedia.org/w/index.php?curid=18503479)
Plum pudding (https://commons.wikimedia.org/wiki/File%3AJersey_Christmas_pudding_pod%C3%AEn_dflieu.jpg
By Man vyi (Self-photographed) [Public domain], via Wikimedia Commons)
Gold foil (By Eckhard Pecher - Own work, CC BY 2.5, https://commons.wikimedia.org/w/index.php?curid=1465931) GCSE Chemistry Revision Alpha Scattering Experiment](https://i.ytimg.com/vi/qAlpNXO_FRE/mqdefault.jpg)


![GCSE Biology Revision Required Practical 2: Culturing Microorganisms (Triple)
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In this video, we start by looking at how we can culture bacteria. We then look at how we can use these techniques to investigate the effect of antibiotics on bacterial growth.
This video is based on the AQA spec. This video may be appropriate for iGCSE / O Level Biology. Please consult your specification. The Amazon link above is an affiliate link. This provides a small commission which helps to support freesciencelessons. The cost remains the same to you. If you prefer not to use this, you can search Amazon for the Freesciencelessons workbooks.
Image credits:
Bacterial culture By Kjaergaard at en.wikipedia [Public domain], via Wikimedia Commons
Agar gel plate By Wikitorre92 - Own work, CC BY-SA 4.0, https://commons.wikimedia.org/w/index.php?curid=45023219
Autoclave By SystecAutoclaves (Own work) [CC BY-SA 4.0 (http://creativecommons.org/licenses/by-sa/4.0)], via Wikimedia Commons
Innoculating loop By Jeffrey M. Vinocur - Own work, CC BY 2.5, https://commons.wikimedia.org/w/index.php?curid=729447
Adhesive tape By BarberJP - Own work, Public Domain, https://commons.wikimedia.org/w/index.php?curid=5040682
Antibiotic discs By CDC/Dr. JJ Farmer (PHIL #3031), 1978. - Obtained from the CDC Public Health Image Library., Public Domain, https://commons.wikimedia.org/w/index.php?curid=1863159
Cheek cells
https://commons.wikimedia.org/wiki/File:Cheekcells_stained.jpg
Mulletsrokk, CC BY-SA 3.0 https://creativecommons.org/licenses/by-sa/3.0, via Wikimedia Commons GCSE Biology Revision Required Practical 2: Culturing Microorganisms (Triple)](https://i.ytimg.com/vi/r7_nj3AZX6w/mqdefault.jpg)



![A Level Biology Revision (Year 13) Thermoregulation in Endotherms
In this video, we look at thermoregulation in endotherms. First we explore the roles of thermoreceptors and the thermoregulatory centre in the hypothalamus. We then look at how endotherms respond to an increase and decrease in core body temperature, including vasodilation and vasoconstriction. Finally, we look at adaptations of endotherms to hot and cold conditions.
Image credits:
Cat
https://commons.wikimedia.org/wiki/File:Cat_Iran.jpg
درفش کاویانی, CC BY-SA 3.0 https://creativecommons.org/licenses/by-sa/3.0, via Wikimedia Commons
Pigeon
https://commons.wikimedia.org/wiki/File:Feral_pigeon_2022_03_18_01.jpg
Alexis Lours, CC BY 4.0 https://creativecommons.org/licenses/by/4.0, via Wikimedia Commons
Human body
https://commons.wikimedia.org/wiki/File:Human_Body_1.jpg
Mikael Häggströmderivative work: Lamilli, CC BY-SA 4.0 https://creativecommons.org/licenses/by-sa/4.0, via Wikimedia Commons
Marathon runner
https://commons.wikimedia.org/wiki/File:Lydd_Half_Marathon_%26_20_Miler_2016_FNK_9168_(25509480890).jpg
Funk Dooby from Kent, UK, CC BY-SA 2.0 https://creativecommons.org/licenses/by-sa/2.0, via Wikimedia Commons
Sweating
https://commons.wikimedia.org/wiki/File:Sweating_at_Wilson_Trail_Stage_One_1.jpg
Minghong, CC BY-SA 4.0 https://creativecommons.org/licenses/by-sa/4.0, via Wikimedia Commons
Dog panting
https://commons.wikimedia.org/wiki/File:Dog_Panting_on_a_Hot_Day_2013.JPG
David Shankbone, CC BY 3.0 https://creativecommons.org/licenses/by/3.0, via Wikimedia Commons
Kangaroo licking to cool down
https://commons.wikimedia.org/wiki/File:Kangaroo_licking_itself_to_cool.jpg
fir0002 flagstaffotos [at] gmail.com Canon 20D + Canon 400mm f/5.6 L, GFDL 1.2 http://www.gnu.org/licenses/old-licenses/fdl-1.2.html, via Wikimedia Commons
Arm hair
https://commons.wikimedia.org/wiki/File:ArmHair.jpg
Zephyris, CC BY-SA 3.0 https://creativecommons.org/licenses/by-sa/3.0, via Wikimedia Commons
Desert fox
https://commons.wikimedia.org/wiki/File:Sleeping_Vulpes_zerda_at_Happy_Hollow,_closeup.jpg
Grendelkhan, CC BY-SA 4.0 https://creativecommons.org/licenses/by-sa/4.0, via Wikimedia Commons
Fluffy pigeon
https://commons.wikimedia.org/wiki/File:Fluffy_pigeon_at_Manasota_Key_Beach,_side_view.jpg
Grendelkhan, CC BY-SA 4.0 https://creativecommons.org/licenses/by-sa/4.0, via Wikimedia Commons
Cold cat
https://commons.wikimedia.org/wiki/File:Cat_on_a_cold_tin_roof geograph.org.uk 434975.jpg
ceridwen / Cat on a cold tin roof
Dog in snow
https://commons.wikimedia.org/wiki/File:Dog_in_snow_jacket.jpg
Magda K from Opole, Poland, CC0, via Wikimedia Commons
Arctic fox
https://commons.wikimedia.org/wiki/File:Arctic_fox_(6375703941).jpg
Emma, CC BY 2.0 https://creativecommons.org/licenses/by/2.0, via Wikimedia Commons
Hedgehog
https://commons.wikimedia.org/wiki/File:Erinaceus_europaeus_LC0119.jpg
I, Jörg Hempel, CC BY-SA 2.0 DE https://creativecommons.org/licenses/by-sa/2.0/de/deed.en, via Wikimedia Commons
Seal
https://commons.wikimedia.org/wiki/File:Arctocephalus_pusillus_2.jpg
© Hans Hillewaert CC BY-SA 3.0 https://creativecommons.org/licenses/by-sa/3.0, via Wikimedia Commons A Level Biology Revision (Year 13) Thermoregulation in Endotherms](https://i.ytimg.com/vi/sJ-6pjb9vDE/mqdefault.jpg)

