Lab 1 Flashcards
what is the name of the reaction
BR Oscillation Reaction
what will the solutions display when they are mixed
chemical oscillation
what is a solution
homogenous mixture consisting of two or more substances in a single phase
what is a solute
substances that in the smallest amount and dissolve/disperse
what is a solvent
substances that are in the bigger amount
- mostly water (gases, liquids, solids dissolved in water are solutes)
what needs to happen for a solute to dissolve in a solvent
solute-solvent forces of attraction are great enough to overcome forces between solute-solute and solvent-solvent
what happens if all 3 forces are equal in strength
substances will be soluble in each other
likes dissolves likes
- charged ions are more attracted to molecules of polar solvents and non-polar molecules are more attracted by non-polar molecules of non-polar solvents
concentration of a solution
measure of the amount of solute in a given amount of solution
(mol solute/L solution)
- many also be expressed as millimolar or micro molar
common terms for molarity
- molality: mol solute/kg solvent
- mole fraction: mol solute/ (mol solute+mol solvent)
- parts by mass: mass solute/mass solution
- parts by volume: volume solute/volume solution
= parts by… are expressed as % similar to ppm/ppb (parts per million/billion)
when are ppm/ppb used
apply to dilute solutions and report concentration of trace components in water
what is a chemical oscillation
cyclic changes occurring within the solution as particular concentrations of solutes rise and diminish in a periodic fashion
molarity for all substances
- 4 solutions total *
A= 2 solute solution: 0.15 M malonic acid and 0.02 M manganese
B= 2 solute solution of 0.20 M potassium iodate and 0.080 M sulphuric acid
C= a 3.6M hydrogen peroxide solution
D= a 3% (w/v) starch solution
When you mix the solutions…
- you mix the 3 at once and add small drops of the 4th one
- if the solute concentrations are correct then it should show colour change for ten minutes
how to know if the cyclic nature occurs
colour change for 10 mins
what are oscillation reactions
- multi step reactions where intermediates are formed, reacted, reformed, re-reacted, and so on.. in a cyclic fashion
- cyclic rise and fall of intermediates is observed through colour change
who made BR reaction
Thomas S. Briggs and Warren C. Raushcer
- gold-yellow to blue to colourless and back again = rise and fall of concentration of iodine containing intermediate and interaction w/ starch
HOI
- hypoiodous acid
= thought to depend on its rise and fall (in I2 and I- concentrations)
I2 and I- concentration
both are high: blue starch-iodide complex
I2 high, I- low: yellow-gold
I2 low, I- high: clear
- oscillations continue until masonic acid or iodate ions are consumed
purpose of H2SO4
purpose of MnSO4
purpose of starch
to keep medium, acidic
to provide Mn2+ which is involved in rxn
indicate presence of I2 and I-
= produces redox reactions to help produce I2 and I- intermediates!