Question

The compound that can not be kept in glass vessel because it reacts with glass is
1. HNO₃
2. HCI
3. HF
4. HBr

Answer 1

Correct Answer - Option 3 : HF

The correct answer is HF.

• Hydrofluoric acid is normally handled in metal apparatus made of copper of Monel and is always stored in plastic bottles.
• The reaction with glass produces the hexafluorosilicate ion, SiF²⁻₆:
  SiO₂(s) + 6HF(aq.) → SiF²⁻₆(aq.) + 2H⁺(aq.) + 2H₂O(l)
• This property is used in the etching of glass.
  • As a result, the glass bottles are slowly corroded or eaten up.
• Gaseous HF is very toxic and should be handled only in a good fume cupboard. Aqueous solutions of HF are called hydrofluoric acid. It is very corrosive, even though it is a weak acid.

• Nitric acid, (HNO₃), colorless, fuming, and highly corrosive liquid.
  • Nitric acid is a nitrogen oxoacid of formula HNO₃ in which the nitrogen atom is bonded to a hydroxy group and by equivalent bonds to the remaining two oxygen atoms. It has a role as a protic solvent and a reagent.
  • It is also known as aqua fortis (Latin for "strong water") and the spirit of niter.
• Hydrochloric acid (HCl), also known as muriatic acid, is an aqueous solution of hydrogen chloride.
  • It is a colorless solution with a distinctively pungent smell.
  • It's used industrially to process steel, the material of choice for suspension bridges and cars and trucks. Hydrochloric acid is also used in the production of batteries, photoflash bulbs, and fireworks.
• Hydrobromic acid (HBr) is a strong acid formed by dissolving the diatomic molecule hydrogen bromide (HBr) in water.
• HCl, HBr, and HI are all strong acids, whereas HF is a weak acid.
  • The acid strength increases as the experimental pKa values decrease in the following order: HF (pKa = 3.1) < HCl (pKa = -6.0) < HBr (pKa = -9.0) < HI (pKa = -9.5).