Density and solubility of the water solution
Solution
It is the liquid which a material dissolved in to liquids such as solution … water or the alcohol
※As for the solution, deepness agrees with all parts
It is a liquid dissolving a material in like solvent … water
It is a material dissolving in a liquid like solute … salt.
When I nominate a salt solution for an example
- Solution … salt solution
- Solvent … water
- Solute … salt
Come to という-like.
A water solution … solvent is solution of the water
Density
I expressed the ratio of solute included in the density … solution. To express it in percentage; the unit is %
Mass} X 100
density =\frac {solute
Because this is official, but mostly there are many problems of the salt,
I think that it is easy to remember the person whom I remembered here.
By the way, when I do expression transformation,
100
There is such a formula, but let’s learn these two formulas because we use this well.
Calculation of the density
[exercise] The pattern that an entrance examination shows well
① With 8 g of salt, I want to make the salt solution of 5% of density. That several g of water is necessary is an answer.
② ①You should put water several g more to make the density of made solution half, or demand で.
[elucidation]
① At first I substitute a value formally. (both formulas are enough, but substitute it for the second formula)
5 100
Therefore because I understood that a salt solution became 160 g,
I subtract 8 g of the solute from here and understand that 152 g of water is necessary.
② This may substitute it formally, but is not so all right because speed is slow.
I pay my attention to the mass of the solute not changing even if I add water how much because it is water to add to make density half.
You should add water so that mass of the solution doubles judging from a conclusion.
Thus, the answer becomes 160 g.
8 160 8 320
Density after the density right before the left poured water poured 160 g of water
I should be able to get an image when I watch a ceremony.
Even if even anything gets caught, is not substitution formally; such; when can consider, calculation speed improves.
By the way, there are the problems of the system to mix a salt solution and a salt solution with, but let’s learn that there because we learn it by an equation of the middle 1 mathematics.
It is to make an equation with quantity of the salt to be important.
Solubility, recrystallization
The quantity of the limit of a material dissolving in water of …100 g of solubility. There is no unit.
Most materials come to have a big solubility at the same time as temperature rises (the quantity of a melting limit increases)
・Even if temperature rises, as for the salt, solubility hardly changes.
・Because temperature rises, solubility decreases calcium hydroxide.
It is the water solution which a solute dissolved in to a saturated water solution … solvent to the limit. (the water solution which can no longer melt)
The graph which expressed the solubility of the solubility curve … material and relations of the temperature
I lower temperature of the recrystallization … solution and vaporize a solvent, and precipitate the solute which was not able to melt as crystallization
For example, from this graph
- Alum dissolves in 100 g of water of 58 degrees Celsius to 50 g
- Alum dissolves in 100 g of water of 40 degrees Celsius to 30 g
I understand ということが.
By the way, the quantity of the limit of a melting solute is proportional to quantity of the water and is related. In other words
- Alum dissolves in 200 g of water of 58 degrees Celsius to 100 g
- Alum dissolves in 50 g of water of 40 degrees Celsius to 15 g
It means.
Calculation of the solubility
[exercise]
I dissolved alum in 100 g of water of 58 degrees Celsius to the limit and cooled this solution to 40 degrees Celsius. Is the recrystallizing alum several g?
[elucidation]
Alum dissolves in 100 g of water of 58 degrees Celsius to 50 g. The alum melts only to 30 g when I cool this to 40 degrees Celsius.
Thus, it is 50 in what melt only to 30 of 50 g – The alum of 30 = 20 g recrystallizes.
※By the way, the quantity of recrystallizing alum becomes 10 g of half in proportion to it when I change the condition called 100 g of first water of this problem into 50 g of water (to half).
Because you often use it by a calculation of the complicated solubility of the most barrier school, you should pour this technique into the corner of the head.