Monday, 25 February 2013

Carbonate content 2 - reaction with hydrochloric acid.

This method describes how to ascertain the relative proportion of carbonate in an ore sample based on the duration of a reaction with HCl.


Conical flask
Balance with .01g resolution
Measuring trays
HCl 2mol/litre
Ore samples
Pestle and mortar
Measuring cylinder


Grind your first sample in the pestle and mortar until it is finely divided into a powder.
Measure out 20ml of acid and add to the measuring cylinder and pour into the conical flask.
Measure out 1g of the ground sample into a measuring tray.
Add the ground sample to the conical flask and start the stopclock, giving the flask a quick swirl to ensure the two mix.
Stop the stopclock when the reaction finishes and no more gas is evolved.

Record the time and move onto your next sample.

Goggles should be worn whenever working with acids.


The longer the reaction continues for, the greater the proportion of carbonate in your sample. Depending on the proportions you may find the reaction completes too quickly to be able to time, or continues for too long. If this is the case you could either adjust the amount of sample used, or change the concentration of the acid.