a contact with the food.
III.9. Effervescence with citric acid and sodium hydrogen carbonate.
We wish to obtain an effervescence in a dish, using sodium hydrogen carbonate NaHCO3 and
some acid, like lemon juice or vinegar.
Sodium hydrogen carbonate NaHCO3, in presence of citric acid, induces causes an
effervescence according this scheme of reaction:
+ + 3 H2O + 3 CO2
Citric acid + 3 sodium bicarbonate _ base from the acid + 3 H2O +3 CO2.
This reaction occurs by the contact of the two reagents, mostly in aqueous solution.
As it is shown above, this reaction releases some carbon dioxide, involving effervescence.
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III.9.3. First test:
· Sodium bicarbonate (powder at 1 % of humidity), supplied by Louis Francois Inc.
· Juice of a freshly squeezed lemon.
· Citric acid (at 1 % of humidity), supplied by Thiercelin Inc.
· Tap water.
· Caster sugar.
1. Prepare 3 different solutions of sodium bicarbonate:
a. Some powder,
b. A solution of tap water with 1% of sodium bicarbonate,
c. A gel made of the former solution with 1% of gelatine.
2. Prepare 3 different solutions of lemon juice:
a. The natural juice
b. A gel made of lemon juice and 1% of gelatine
c. A gel made of lemon juice and 0.5% of gelatine.
3. Put a teaspoon of one solution of sodium bicarbonate in contact with a teaspoon of one solution of
lemon juice in a plate. Then taste the mixture.
In the mouth, the reaction of effervescence works after several seconds, but its intensity is not
It has to be noted that the mixture gives an unpleasant sensation before beginning of the reaction
between the two reagents (effervescence).
The results are given in the appendix 9.
III.9.3.4. Discussion/ Interpretation:
Sodium hydrogen carbonate gives an unpleasant taste. It has to be employed with a minimum
quantity, whereas the acid would be used in excess.
The effervescence is not hard enough and it takes time to start the effervescence. A solution