Methods of heating substances

In a nutshell

When heating substances in the lab it is important to consider the safest and most appropriate method for heating the substance for the reaction.

Heating methods

Heating methods are used in chemistry practicals to heat up reaction mixtures or substances to a specific temperature. There are different methods such as using a bunsen burner, water baths or an electric heater.

mETHOD	dESCRIPTION	aDVANTAGES	Disadvantages
Bunsen burners	A piece of equipment that connects to a gas tap, which can produce an open flame, that can be adjusted to be hotter or cooler.	This method can heat substances quickly.	This method cannot heat to specific temperatures easily.
Water bath	A beaker of water is heated using a Bunsen burner. A thermometer is used to observe the temperature.	This method can heat to specific temperatures. This method heats the reaction evenly, because the water surrounds the reaction.	It is difficult to keep the temperature constant. It is not possible to heat beyond $100^oC$ , because the water evaporates.
Electric water bath	A container with a heating element that heats water to a specific temperature, which the user can adjust.	This method allows specific temperatures to be maintained easily. This method heats the reaction evenly, because the water surrounds the reaction.	It is not possible to heat beyond $100 ^oC$ , because the water evaporates.
Electric heaters (hot plate)	These heaters have a metal plate that can be heated to specific temperatures, which the user can adjust.	This method allows very high temperatures to be reached. This method allows specific temperatures to be maintained easily.	This method requires stirring to heat the reaction evenly.

How to use the different methods

Bunsen burners

Biology; Practical skills; KS4 Year 10; Methods of heating substances

A bunsen burner on a heating mat and underneath a tripod is shown.

Procedure

1.	Place the Bunsen burner on a heat proof mat.
2.	Close the hole on the Bunsen burner and connect the hose to the gas tap.
3.	Light a splint and hold it over the Bunsen burner.
4.	Turn on the gas.
5.	When heating a container with a substance in the flame, hold the container with a pair of tongs in the flame.
6.	When heating a container with a substance over the flame, place a tripod and gauze over the Bunsen burner before it is lit. Then place the container on top of the gauze with a pair of tongs.
7.	The heat of the flame can be adjusted by opening and closing the hole on the Bunsen burner. By opening the hole, the flame will get hotter and turn blue, the hottest part of the flame is just above the inner cone of the flame. Closing the flame, makes it cooler and turns the flame yellow.
8.	When not using the Bunsen burner, leave the hole closed, so the flame is yellow and visibly on.

Water bath

Biology; Practical skills; KS4 Year 10; Methods of heating substances

1.	Beaker
2.	Solution
3.	Heating mat
4.	Tripod
5.	Bunsen burner
6.	Heating mat

Procedure

1.	Set up a Bunsen burner, tripod and gauze, as described above.
2.	Place a beaker of water on top of the gauze with a pair of tongs.
3.	Use a thermometer to observe the temperature of the water.
4.	Place the container with the substance in it, inside the beaker of water, being careful to ensure no water enters the reaction vessel.
5.	Adjust the Bunsen burner flame to adjust the temperature.

Electric water bath

Biology; Practical skills; KS4 Year 10; Methods of heating substances

1.	Rubber duck
2.	Reaction mixture in a conical flask
3.	Ball

Procedure

1.	Plug the water bath into a socket and fill the water bath with water.
2.	Turn on the water bath and set the temperature.
3.	Allow the water to heat up.
4.	Place the reaction vessel in the water using tongs.
5.	Ensure the water level in the bath is just above the level of the substance in the reaction vessel.

Electric heater (hot plate)

Biology; Practical skills; KS4 Year 10; Methods of heating substances

An electric heater is shown. An electric heater uses electricity to generate heat.

Procedure

1.	Plug the hot plate into a socket.
2.	Set the temperature.
3.	Place the reaction vessel on the hot plate.
4.	Stir the reaction regularly, to ensure the reaction is heated evenly.