It is important to note that many bases are as corrosive and as dangerous as acids. Caustic soda, an ingredient found in many cleaning fluids, is a corrosive base and must be handled with care.
Working safely with corrosives
If you saw the corrosive hazard symbol on a substance you were about to use, what safety precautions would you take?
The hazards of using acids and alkalis depend on two factors: z z
The type of acid or alkali you are using. zz Whether the acid or alkali is dilute or concentrated. Concentration of Acids and Bases
The acid found in vinegar is dilute ethanoic acid. Adding vinegar to food for flavour does not cause us any harm, yet concentrated ethanoic acid causes severe burns and catches fire easily.
So, what is the difference between vinegar and concentrated ethanoic acid? Pure ethanoic acid does not contain water, whereas vinegar does. The acid in vinegar has been diluted, which makes it safe to eat.
Acidic and alkaline solutions are not all the same: z z
z z
Some solutions contain a large amount of acid or alkali particles. These solutions are described as concentrated.
Other solutions contain very few particles of acid or alkali. These are described as dilute.
Acids and alkalis are made less concentrated by diluting them carefully with water.
z z zz
Concentrated acids and alkalis are corrosive.
Dilute acids and alkalis are not corrosive but may hurt if they get into cuts on the skin.
Dilute versus concentrated
Bottle A contains 350 g of acid in one litre of the solution. Bottle B contains 3.7 g of the same acid in half a litre.
1. Which acid is more dilute? 2. Which acid is more concentrated?
3. What hazard symbol would you expect to see on the bottle for the concentrated acid?
4. If water was added to container B to bring it to the same volume as container A, how would the concentration of the solution in container B change?
A z Fig. 13.1.5 225 A B B z Fig. 13.1.5
The acid in vinegar is diluted, making it safe to eat
