Question

a) Why are metal stoppers not used in bottles that are used to store acids in the laboratory?​ [1.5 Marks]

b) Between phenolphthalein and methyl orange, which will not indicate acids? [1.5 Marks]

Answer 1

a) Acids react with metals to produce metal salt and flammable hydrogen gas.
So, metal stoppers are not used for bottles to store acids in the laboratory.
Containers or bottles made of glass are ideal for storage of acid due to its chemical inertness. [1.5 Marks]

b) Methyl orange turns red in acidic solutions and yellow in basic solutions.
Phenolphthalein shows a colour change only in basic medium and no colour change in acidic or neutral solutions.
Hence, phenolphthalein would not be able to indicate acids. [1.5 Marks]