Download Matter Notes X Law of Definite Proportions – or Constant

Matter Notes
X
Law of Definite Proportions – or Constant Composition elemental composition of a pure substance is always the same,
ex. Water (Proust)
X Law of Multiple Proportions – (Dalton) If two elements form
more than one compound, the masses of one that combine with a
given mass of the other, are in the ratio of small whole numbers.
Ex. Water vs. Hydrogen Peroxide
X Law of Conservation of Mass (Lavoisier) Total mass before a
chemical rxn = total mass after chem. Rxn.
X Solutions – Homogeneous Mixtures – Single phase
Solute – Substance that is dissolved
Solvent – Substance doing the dissolving
Solubility affected by nature of the solute, nature of solvent,
Temperature
Dissolving illustrates equilibrium concept – point at which rate
of dissolution = rate of return to solid solute
At equilibrium solution is saturated – max amount of
solid is dissolved
Unsaturated – Can dissolve more, not at equilibrium
Supersaturated – Solution holds more solute than
normally dissolved in a saturated sol’n at the
same temp. – unstable, crystallizes out
Gas solubility decreases with increased temp – Reducing the
Pressure at a liquid’s surface enables gas to escape
Ex. Carbon dioxide in soda – effervescence
P1/S1 = P2/S2 same T Henry’s Law
Concentration
Dilute- Small amount of solute per volume of sol’n
Concentrated – Large amount of solute per volume of
sol’n
Can express concentration in terms of mass percentage
(mass solute per 100g sol’n) or by using mass volume
relationships (1.00gsugar in 1.00L = 1.00g/L)
Ex. Commercial Sulfuric Acid is sold as a 98% sol’n
in water, having a D=1.84g/mL. The solute in
solution is the sulfuric acid. Calculate the
grams of solute in:
a. 1.00L of sol’n
b. 200. mL of sol’n
a. 1.00L has a mass of 1.00L x 1000mL/L x
1.84g/mL = 1840g
Since it is 98% by mass: 1840g x .98 = 1800g
b. ?g solute = 200.mL x 1.00 L sol’n/1000mL x
1840g sol’n/L sol’n x 98 g solute/100g
sol’n = 360g solute
Suspension – Heterogeneous, multi-phase system. Can be
Separated by filtration ex: muddy water
Colloid – Particles suspended as in a suspension but do not
separate upon standing; particles are of substantial
enough size to reflect light (Tyndall Effect) – The
scattering of a beam of visible light by the particles
in a colloidal dispersion.
Ex. – milk (emulsion) fog (Tyndall as headlights of a car
disperse light) mist, blood, gelatins, jelly whipped
cream paint smoke butter marshmallow
Continuous phase – dispersion medium
Dispersed phase – internal phase particles are usually
invisible