#PORUS POT HOW TO#

Half fill the trough with water and fill the test tubes with water, leaving them submerged in the trough.Assemble the apparatus within easy reach of a Bunsen flame.The assembled apparatus for producing and collecting ethene gas Procedure

For demonstration or class use square, clear, plastic sandwich boxes make excellent troughs.

The trough needs to be small enough to match the scale of gas collection вЂ“ the large traditional trough which used to be used with gas jars is not appropriate.

Note that the effectiveness of the home-made valve is variable, and for class use a supply of spares should be provided. The resulting assembly is fitted onto the lower end of the delivery tube. A 1 cm long slit is carefully cut into the middle of the rubber tubing with a scalpel. The Bunsen valve is constructed from a short length (about 3 cm) of clean, unused, soft rubber tubing, with one end stoppered with a short length of glass rod.

The purpose of the Bunsen valveВ is to prevent suck-back of water into the hot tube when heating is stopped and the gas inside the apparatus contracts on cooling.

Use a Bunsen valve to prevent suck-back of water into the delivery tube as the apparatus cools and contracts

A large, 150 mm x 25 mm, hard glass (borosilicate) test tube.

Dilute sulfuric acid, 0.1 MВ - see CLEAPSS Hazcard and CLEAPSSВ Recipe Book.

1 dm 3 of stock solution is made by dissolving 1.6 g of potassium permanganate(VII) crystals in 1 dm 3 of 0.1 MВ sulfuric acid.

Potassium manganate(VII) (potassium permanganate) solution, about 0.01 M - see CLEAPSSВ Hazcard and CLEAPSSВ Recipe Book.В The potassium permanganate(VII) solution is made by dissolving solid potassium permanganate(VII) in 0.1 MВ sulfuric acid.

Bromine water (HARMFUL)В - see CLEAPSSВ Hazcard.

Ethanol (IDA, Industrial Denatured Alcohol) (HIGHLY FLAMMABLE, HARMFUL) - see CLEAPSSВ Hazcard.

For a demonstration, the class and teacher should be protected by safety screens in case of unexpected suck-back causing the hot tube to shatter on a demonstration bench.

Read our standard health and safety guidance.

Acidified potassium manganate(VII) (potassium permanganate) solution, about 0.01 M, aboutВ 5 cm 3 (see note 6 below).

Bromine water, 0.02 M (HARMFUL), about 5 cm 3,В diluted to pale orange-brown.

Pumice stone or porous pot (unglazed), a supply of small fragments (about pea-sized).

Mineral wool, sufficient for a loosely-packed wad to absorb the liquid at the bottom of the test tube.

Ethanol (IDA, industrial denatured alcohol) (HIGHLY FLAMMABLE, HARMFUL), 2вЂ“3 cm 3 (provided in small bottles).

Glass or plastic trough, small (see note 10).

Rubber bung, 1 hole, to fit boiling tube.A class experiment takes longer, probably about 30вЂ“40 minutes.ДЄlternatively the teacher could demonstrate the dehydration but get the students to perform the test tube tests for the product. The main risk to be considered in making the choice is the reliability of the studentвЂ™s involved handling very hot glassware and manipulating the apparatus for safe gas collection over water, while avoiding suck-back of cold water into the hot tube.ДЄ demonstration will take about 10вЂ“15 minutes, with a few more minutes for testing the gases. The experiment can be performed as a demonstration or as a class experiment according to circumstances. After collecting the gas over water, students can test it for the typical properties of an unsaturated hydrocarbon.

#PORUS POT HOW TO#

In this experiment, students observe how to produce ethene gas by dehydrating ethanol vapour over a heated catalyst. Hamied Inspirational Chemistry Programme.Introductory maths for higher education.The physics of restoration and conservation.The subsequent reduction in pressure inside the pot in step 4, is caused by the heavier, slower carbon dioxide molecules diffusing into the pot more slowly than the air diffuses out.In step 2, the manometer will show the pressure in the pot increasing as the lighter, faster hydrogen molecules diffuse in faster than the air diffuses out.However, they may need careful explanations for less able students. Students - and teachers! - always enjoy these demonstrations since they can seem counter-intuitive.Remove the cover of the beaker of carbon dioxide and lower the other porous pot into it.When the pressure difference is a maximum, remove the beaker and show the process reversing.Invert the beaker of hydrogen, hold it in a clamp, remove its cover, and raise the porous pot into the jar.Allow enough time for diffusion to cause the air pressures inside and outside the pots to be more or less equal. Put coloured water into each manometer, and insert the bungs into their porous pot.

Porus pot