Important Concepts Flashcards
What is an isotope
Atoms of the same element with a different number of neutrons
What is an allotrope
Different forms of the same element eg. Diamond & carbon
What is a part per million
1ppm = 1 (unit) in 10^6(unit)
Why is back titration used?
- solid is insoluble in water but soluble in acid/base
- reactants are volatile (eg, ammonia)
- reaction is too slow
What acid medium cannot be used in a manganate titration?
HNO3 & HCL
Can be used: H2SO4 (dilute)
Why is starch only added when solution turns pale yellow in a Iodine-thiosulfate titration ?
It prevents the formation of insoluble starch - iodine complex that occurs at high concentrations of iodine
Electronegativity trend?
Increasing across period
Decreasing down group
What are the 3 types of intermolecular forces of interaction between covalent molecules?
id-id: instantaneous dipole - induced dipole
pd-pd: permanent dipole - permanent dipole
hydrogen bonding
Answer structure for boiling melting point question
- Structure
- IMF/ inter atomic bonds broken during change
- compare bond strength
- More energy for stronger bonds
- Conclude w boiling/ melting point
How to determine solubility of compounds with IMF/ inter atomic bonds
Energy released from formation of solute-solvent interactions
>
Energy taken to break interactions between individual compounds (solute & solvent)
*keyword: energetically favorable
Answer structure to comparing solubility using IMF
- Structure
- Solute-solute / solvent-solvent interactions broken
- Solute-solvent interactions formed
- Compare energy of 2. And 3.
- If 3>2, energetically favorable
