Hydrogen Halides Flashcards
Give equation for atom economy
Molar mass of useful product
Total molar mass of starting materials X100
Greater atom economy means…
Less waste
What is atom economy if there is 1 product in reaction?
100%
How is can hydrogen chloride be prepared?
- by reacting NaCl with H2SO4 to produce NaHSO4 and HCl
What is observed when HCl is produced from reacting sodium chloride and an acid?
White fumes
Why can HCl be prepared using sodium chloride, but HBr can’t be prepared using sodium bromide?
- bromide ions are stronger reducing agents that chloride ions
- reduce sulfuric acid to sulphur dioxide
What is produced when NaBr reacts with H2SO4?
SO2 + Br2 + 2H2O
How can hydrogen bromide be prepared?
Concentrated phosphoric acid is used, will not be reduced by bromide ions
How can hydrogen iodide be prepared?
- using concentrated phosphoric acid, will not be reduced by iodide ions
What is produced when NaI reacts with H2SO4?
H2S + 4I2 + 4H2O
Hydrogen sulfate smells of rotten eggs
What trends can be seen down the group of hydrogen halides in thermal stability and why?
- decreases down group (HI breaks down at lower temp than HF)
- hydrogen - halide bond enthalpy decreases down group
When heated in laboratory, what does HF do?
Does not decompose
When heated in laboratory, what does HCl do?
Does no decompose
When heated in lab, what does HBr do?
Partially decomposes with strong heating
- brown Br2 gas given off
When heated in lab what does HI do?
- large amounts of violet gas produced when hot needle plunged in HI gas
