Chapter 4 - Acids & Redox Flashcards
Acids
When dissolved in water an acid releases hydrogen ions as protons, H+
Strong acids vs weak acids
Strong acids release all hydrogen atoms into H+ and completely dissociates in aqueous solution e.g. Hydrochloric acid
Weak acids release a small proportion of hydrogen atoms into H+ and partially dissociates in aqueous solution e.g. ethanoic acid
Bases
Neutralise acids to form salts
Alkalis
Base that dissolves in water releasing hydroxide ions into the solution
neutralisation
- acid H+ ions react with a base to form a salt and water
acid + metal oxide/hydroxide
salt + water
acid + metal
salt + hydrogen
acid + metal carbonate
salt + water + carbon dioxide
what’s a titration
- technique used to accurately measure the volume of one solution that reacts exactly with another
- used to find:
- conc. of solution
- purity of substance
- identifying unknown chemicals
how to make standard solution
- weigh solid
- dissolve solid in beaker - make sure to wash
- transfer into volumetric flask - wash again
- fill with more water till graduation line
- add lid and invert several times
mean titre
- calculate using concordant results only
(within 0.10cm3) - give all results to 2 d.p.
Oxidation no.
- based on a set of rules that apply to atoms
- can be thought as the no. of electrons involved in bonding to a different element
oxidation no. rules (x4)
- for pure element no. is 0
- for simple ions oxidation no. is ion charge
- for compounds the oxidation no. adds to 0
- for polyatomic ions, the oxidation no. adds to overall charge on ion
special cases of oxidation no.
H in metal hydrides e.g. NaH is -1
O in peroxides e.g. H2O2 is -1
O bonded to F e.g. F2O is +2
redox reaction
oxidation & reduction happen at the same time
