Definition SOLUTION定义解决的方案共36页

As the soda becomes warm, the gas molecules begin to move faster and evaporate out of the soda.
(2) Solubility & Pressure
Changes in pressure have the largest effect on gases dissolved in liquids.
In Kool-aid example, more or less sugar could be added to make the solution more or less concentrated.
A True Solution
Properties
2) The dissolved solute is molecular or ionic in size.
A True Solution
Properties
5) The solute can be separated from the solvent by physical means (evaporation, filtration, boiling, etc)
Recall the first lab where we boiled salt water, after the water evaporated, the salt was left at the bottom.
Dissolving
How do substances dissolve?
Diffusion
Molecules travel from areas of high concentration to areas of low concentration.
Solubility describes how likely one substance will dissolve in another.
50 C
How much more would the first cup dissolve?
Solubility Curves
Can use a graph to represent solubility Y-axis = grams of solute per 100g H2O X-axis = temperature
Saturated, Unsaturated, & Supersaturated
SATURATED
Sol’ns
Holds the maximum amount of solute in the dissolved state
No more solute can be added and still dissolve.
As more of the solute dissolves, the area shrinks and dissolving slows down.
What Affects a Substance’s Solubility?
Question: When making Jell-o, why do the directions
Canned at high pressures.
When it’s opened, the pressure inside is reduced to the atmospheric pressure, and the excess dissolved CO2 bubbles out of the sol’n.
The sugar in the packet dissolves into separate sugar molecules
A True Solution
Properties
3) It is either colorless or transparent (not cloudy)
A True Solution
+=
1) solute—part being dissolved (sugar) 2) solvent—part doing dissolving (water)
A True Solution
5 Properties of True Solutions
1) mixture is homogenous and the ratios of solvent to solute can be varied.
for liquids, this causes the solvent molecules to move faster and bump into the solute particles more often and harder, breaking them apart faster.
(2) AGITATION OR STIRRING
supersaturated solution coming out of supersaturation. This reaction is exothermic. Cold packs work the same way but are endothermic reactions.
Can result in a solid, liquid, or gas
What are some examples?
Shampoo Soft drinks Air Gasoline steel
What do you need to make a solution?
Example: Kool-aid, basically sugar water
(3) The Nature of the Solute and the Solvent
Explain why water and oil do not mix? Like dissolves like Polar substances dissolve in other polar
substances and nonpolar dissolve in nonpolar. Oil is nonpolar and water is polar.
this physically helps the solute particles diffuse by distributing them to all parts of the solvent.
(3)BREAK IT DOWN
The smaller the particle, the faster it dissolves
UNSATURATED
More solute could be added and still dissolve.
SUPERSATURATED
Holds more solute than the max.
Very unstable and have to be prepared in a special way.
How can I make a solute dissolve faster?
(4) CONCENTRATION
The closer you get to the saturation point, the slower the dissolving occurs
The solute dissolves quickly at first because there is a lot of area to dissolve into
tell you to pour the packet into hot water and then cool it?
Why can’t you just pour it in cold water and then drink it right away?
What 3 factors affect the Solubility of substances?
Nonpolar vs. Polar
When nonpolar substances dissolve in one another, they simply mix.
When polar substances dissolve, electrical reactions pull apart the molecules.
Different substances will have different curves on the graph.
What’s
happening
Hale Waihona Puke with HCl,NH3, and SO2 (dotted
lines)
Solubility of Gases
SODA The solubility of gases decreases with increasing temperatures. Can you think of a situation where this principle
Pressure and solubility vary directly.
As the pressure increases, the solubility increases.
Back to the Soda
Why does a can of soda fizz when it’s opened?
(1) Temperature For LIQUIDS:
More solute can be dissolved if you use warm solvents.
Why?
The KMT of course
Which one would dissolve more salt?
100 C
is illustrated? (hint: many of you have one at lunch time)
SODA
Cold soda is more fizzy because more gas is dissolved in the soda.
Why does soda become flat as it warms to room temperature? (remember the KMT)
Solubility
Amount of solute that can dissolve in the solvent.
Solubility varies with temperature.
4 ways to make a solute dissolve faster?
(1)INCREASE THE TEMPERATURE
Properties
4) The solute is uniformly distributed and doesn’t settle out over time.
After an hour, the solution should still look the same. No chunks at the bottom or top…think of hot chocolate when it sits for a while
Supersaturated Solutions
Hand/foot warmer packs used for cold weather are examples.
Activated when they are crushed The heat generated is a result of the
Definition: SOLUTION
A system in which one or more substances are homogenously mixed or dissolved in another substance.
In other words: two chemicals mixed together completely.