mole concept and redox Flashcards
isotope definition
elements with the same number of protons but different number of neutrons
yield definition
→ mass of a product formed in a chemical reaction
→ Theoretical yield: mass of product calculated from the chemcial equation based on the amount of limiting reagent used
→ Actual yield: mass of product that is actually obtained in the reaction during the experiment (usually < than theoretical yield)
avogadros hypothesis
Equal volumes of all gases under the same conditions of temperature and pressure contain the same number of molecules
volume units conversion
1m3 = 1000dm3
1 dm3 = 1000cm3
hydrocarbon combustion eq
CxHy + (x + y/4) O2 = xCO2 + y/2 H2O
definitions of oxidation and reduction
Oxidation
- Gain O2
- Lose H2
- Lose electrons
- Increase oxidation number
vice versa for reduction
balancing redox equation in acidic and basic medium
acidic: ehhee
- element, h2o to balance oxygen, h+ to balance hydrogen, electrons to balance change, equate no.of electrons
basic: ehhe oh e
- element, h2o to balance oxygen, h+ to balance hydrogen, electrons to balance change, oh- to balance H+, form H2O, equate no. of electrons
oxidation for c2o4 2-
C2O4 2- –> 2CO2 + 2e-
what type of agent is KMnO4 (oxidising/reducing)
strong oxidising agent
what is KMnO4 reduced to in acidic and basic mediums + colour
acidic: Mn2+ (faint pink)
basic: MnO2 (brown/black solid)
what type of agent is thiosulfate
reducing
why is iodine titrated immediately
it is volatile
why only add starch halfway into the expt
to prevent the iodine to be trapped in the spiral starch molecule and lead to inaccurate results
why does the titrated solution become blue again after a while
the iodide is oxidised by the air to form iodine which reacts with starch to form the starch iodine complex with a blue colour
