ES 6 Flashcards
What is atom economy?
The percentage of reactants ending up in the desired products
What does a greater atom economy mean?
Less waste
Equation for percentage atom economy
%atom economy = (RFM of desired product / RFM of all reactants used) x 100
How to make hydrochloride acid as a co-product
1) ethene + chlorine -> 1,2 dichloroethane
2) 1,2 dichloroethane -> chloroethene + hydrogen chloride
3) hydrogen chloride converted to HCl by passing it through water
What is the strongest oxidising agent in group 7?
Flourine
Why are fluoride ions poor reducing agents?
- Flouride ions have a low tendency to lose electrons
- and turn back into atoms
- so are difficult to oxidise
What is the relationship between group 7 and oxidising agents?
As you go down group 7 the elements become weaker oxidising agents
What is the relationship between group 7 ions and reducing agents?
As you go down group 7, they become stronger reducing agents
Sodium fluoride OR chloride + concentrated acid —> ?
Hydrogen flouride OR chloride gas (white fumes)
Why is adding sulfuric acid to sodium bromide a bad way to make hydrogen bromide gas?
Because it won’t be pure
How do we make pure Hydrogen Iodide or Hydrogen bromide?
Use phosphoric acid as, unlike the sulfuric acid, the concentrated phosphoric acid will not be reduced so a pure hydrogen halide can be collected
What happens to hydrogen halide thermal stability as you go down the group?
- Decreases
- As bond strength decreases
- So less energy is needed to break the bond
What happens when HF and HCl is heated in a lab?
Isn’t broken down
What happens if HBr is heated in a lab?
Brown bromine gas is made
2HBr(g) -> H2(g) + Br2(g)
What happens if HI is heated in a lab?
Purple gaseous iodine is made
ONLY IF A RED HOT NEEDLE IS PUNGED INTO HI
