CHEM 5 Flashcards
Contact process equations between V2O5 from sulfur dioxide and sulfur trioxide
SO2 + V2O5 > SO3 + V2O4
O2 + 2V2O4 > 2V2O5
How does a catalyst speed up a reaction?
It provides an alternative route with a lower activation energy
Why does poisoning effect a heterogeneous catalyst
The poison attaches to the surface
Definition for standard hydrogen electrode
The standard reference electrode for measuring the electrode potentials of cells. The SHE is assigned 0V when operating under standard conditions. The cell consists of hydrogen gas at 1 bar bubbling over a platinum electrode dipped in 1 moldm3 of HCl
Advantage of fuel cells over rechargeable cells
Fuel can be supplied constantly
They can be operated without the need for stopping to recharge
Why can hydrogen-oxygen not be regarded as a source of energy which is carbon neutral?
Hydrogen can be obtained from a source which is not carbon neutral. Like methane
Why is the electron affinity of chlorine exothermic?
The chloride ion is more stable than the chlorine atom
Meaning of the perfect ionic model
It does not show any covalent character
Why is the calculated value of lattice dissociation larger than the theoretical value
The molecule shows covalent character.
The forces in the lattice are stronger than pure ionic attractions
Explain the electronegativities across period 3
Electronegativity increases
Increase in nuclear charge
Same number of electron shells
Attraction of bond pair to the nucleus increases
Why are some transition metal ions coloured and some not eg (Ti(III) and Ti(IV))
Ti(III) has a d electron that can be excited to a higher level. This absorbs one colour of light from white light.
Ti(IV) has no d electron transition with energy equal to that of visible light
Why is a spectrometer used to measure concentration of coloured ions
Rapid determination of concentration
Does not use up any reagent
