Solutions and Solubility
Mixtures • Solutions are a type of mixture, so to understand solutions, first we have to know what a mixture is… • A mixture is a combination of two or more substances. Each substance keeps it’s own properties, even though it is mixed with another substance. They do not combine to form a new chemical substance
Mixtures • Mixtures are all around us: raisin bran, cakes, soda, soup, salad, rocks, sweet tea, trail mix, etc.
Mixtures • There are 2 types of mixtures: – Homogeneous mixtures: everything in the mixture is even spread out and thoroughly mixed • If you took 2 spoonfuls of this type of mixture, they would be exactly alike – Heterogeneous mixtures: there is more of 1 substance than another and they are not evenly spread out and thoroughly mixed • If you took 2 spoonfuls of this type of mixture, they would not be exactly the same
Solutions • Solutions are a type of homogeneous mixture • We call it a solution when 1 substance dissolves into another substance – An example is sweet tea…the sugar dissolves in the tea – Another example is soda…the carbon dioxide dissolves in the liquid soda – Another example is air…the oxygen dissolves in the nitrogen – Another example is a metal alloy like steel, made of iron and carbon
Solutions • We give special names to the substances in a solution – The material that is doing the dissolving is called the solvent. • So many things dissolve in water that they call it the “Universal Solvent. ” It is the most common solvent – The material that is being dissolved is called the solute. – There is usually more solvent in a solution than solute
Solutions • With our sweet tea example, the tea would be the solvent and the sugar would be the solute.
Solutions • By now you should see, solutions aren’t always solids and liquids Gas-Gas Air Gas-Liquid Carbon Dioxide in Soda Liquid-Liquid Gasoline Liquid-Solid Dental Fillings Solid-Solid Sterling Silver
Solubility • Solubility is the amount of solute that can be dissolved in a specific volume of solvent under certain conditions – Solubility basically tells us how well the solute will dissolve in the solvent
Solubility • Several factors can affect solubility – Temperature of the solvent • You can dissolve more sugar in hot tea than you can in cold tea • You can dissolve less gas in a hot liquid than in a cold liquid – Pressure of the system • A closed soda can has more carbon dioxide in it than an open one because the closed can is under pressure
Solubility • The Chemical Nature of the Solvent – Some solvents, like water, naturally dissolve more substances than other solvents do. • Stirring and Particle Size can affect how fast a solute dissolves in a solvent
Saturation • A solvent is said to be “saturated” when it is holding as much solute as it possibly can and if you add any more solute, it will start to come out of solution – An example is when you have extra sugar at the bottom of your sweet tea. The tea can’t hold any more sugar…it is saturated.
• Solubility is not affected by the amount of matter present. It is just like density, melting point and boiling point in that way
References • www. chem 4 kids. com