Matter Solution PreAP

Define Solution 1. A solution is a uniform, homogeneous mixture of two or more substances. 2. It consist of two parts: – a. solute - the substance that dissolves and is present in small amounts. – b. solvent- the dissolving substance. 3. The formation of a solution is not a chemical interaction, therefore they do not conform to the law of definite proportions 4. A mixture is a solution if: – a. The particles of the solute and solvent are the size of the molecules or smaller. – b. The solute particles are evenly dispersed throughout the solute. – c. The dissolved particles will not come out of solution. – d. The solution is clear and transparent. – e. The solution cannot be separated by filtration. 5. The following should be considered: – a. If a polar solvent and a polar solute are mixed, then a solution is likely. – b. If a polar solvent and a nonpolar solute are mixed, then a solution is not likely. – c. If a nonpolar solvent and a nonpolar solute are mixed, then a solution is likely. – d. If a nonpolar solvent and a polar solute are mixed, then a solution is not likely.

Define Solutions 6. If a substance mixes evenly with another substance, both substances are said to be miscible. 7. If a substance do not mix evenly with another substance, both substances are said to be immiscible. 8. The process can be summarized as “ like dissolves like”. 9. Solutions are formed by the process of solvation. – a. The solute particles separate from the solid crystal. – b. The solvent particles move apart. – c. Solute particles are attracted to the solvent particles and are surrounded by the solvent molecules. 10. Solutions in which the solvent is water are called aqueous (aq) solutions. 11. Solutions in which the solvent is alcohol are called tinture solutions.

Types of Solutions: Colloids and Suspensions A. Suspensions 1. Suspensions are dispersions of particles larger than 100 nm in a continuous medium. 2. Suspensions settle out solution. 3. Suspensions can be separated by filtration and membrane. 4. Suspensions scatter light. 5. Suspensions can not affect the colligative properties.

B. Colloids 1. Colloids are dispersion of particles from 1 nm to 100 nm in at least one dimension in a continuous medium. 2. Colloids do not settle out of solution. 3. Colloids pass unchanged through ordinary filter paper but can be separated by a membrane. 4. Colloid scatter light (called the Tyndall effect). 5. Colloids can not affect the colligative properties. 6. Colloids experience Brownian motion which is continuous random motion caused by the bombardment of the colloid particles by the particle of the medium. 7. Emulsions are colloidal dispersions of liquids in liquids.

Water of Hydration 1. Crystals that are chemically bonded to water molecules are called hydrated crystals and the water is called water of hydration. ex. CuSO 4 5 H 2 O 2. It is possible effloresce (remove) the water from hydrated crystals by either raising the temperature or lowering the pressure or both. 3. The resulting compound becomes anhydrous meaning without water. 4. Anhydrous substances have a strong attraction to water. 5. Substances that absorb water out of the air are called hygroscopic and are good desiccants (drying agents). 6. When substance absorb enough water to dissolve into liquid form are called deliquescent.

Properties of Liquids-Water 1. Water is a triatomic molecule with covalent H-O bonds. 2. Water experiences high surface tension and hydrogen bonding. 3. Water molecules are polar. 4. Water absorbs more energy than most liquids: –a–a. High boiling point –b–b. High specific heat –c–c. High heat of vaporization 5. Liquids, particularly water, have a property known as surface tension. 6. Surface tension allows the liquid to behave like it has an elastic skin. 7. It is the inward force or pull which tends to minimize surface area. 8. Surface tension is caused by the intermolecular forces within the liquid. –a–a. The intermolecular forces between the interior liquid molecules are the same in every direction. –b–b. However, the forces on the surface are not the same. –c–c. The surface molecules experience forces that attract down or laterally. –d–d. The difference is what causes surface tension and capillary rise.

9. Liquids that have hydrogen in the molecular structure experience hydrogen bonding. 10. This occurs when the hydrogen of one of the molecules is attracted to another atom on another molecule with unshared pair of electrons. 11. An extensive network of hydrogen bond tightly holds the molecules in liquid water together. 12. The attractive force of the hydrogen bond is not as strong as a chemical bond 13. Water is denser in its liquid form than in its solid form (ice). 14. Ice expands to an open crystal lattice structure. 15. The molecules are further apart than they are in liquid with empty space between the molecule.

Electrolytes and Nonelectrolytes 1. Compounds that conduct an electrical charge in an aqueous solution are called electrolyte. 2. All ionic compounds are electrolytes. 3. Compounds that do not conduct an electrical charge in an aqueous solution are called nonelectrolyte. 4. Most molecular or organic compounds are nonelectrolytes.

Solubility There are thousands upon thousands of reactions that occur in the world, and most of them take place in water (aqueous) solutions. When certain cations and anions are combined, water-insoluble ionic compounds may form. (Cations are positively charged ions and anions are negatively charged ions.) When these ions are in separate aqueous solutions and then brought together, an insoluble solid, or precipitate forms. The precipitate is an ionic compound (often called a salt) that forms because certain ions attract each other so strongly that they are removed from the water solution as the product of a chemical reaction. A double-replacement reaction is one type of precipitation reaction where a precipitate forms when one of the products is insoluble. Look at the example of the reaction between solutions of zinc nitrate and sodium carbonate that you observed in the activity: Zinc nitrate (aq) + sodium carbonate (aq) → sodium nitrate (aq) + zinc carbonate (s) –Zn(NO 3 ) 2(aq) + Na 2 CO 3(aq) → 2NaNO 3(aq) + ZnCO 3(s) Note that (aq) means a compound is in aqueous solution, and (s) means that a solid has formed (the precipitate).

Simple Rules for Solubility of Compounds in Water 1. Most nitrate (NO 3 –1 ), acetate (CH 3 COO –1 ), and perchlorate (ClO 4 –1 ) compounds are soluble. 2. Group 1A metal (Li +1, Na +1, and K +1 ) and ammonium (NH 4 +1 ) compounds are soluble. 3. Most chloride (Cl –1 ), bromide (Br –1 ), and iodide (I –1 ) compounds are soluble. The most notable exceptions are when these anions are combined with Cu +1, Ag +1, Pb 2+, Hg 2+, and Hg Most sulfate (SO 4 2– ) compounds are soluble, except when they are combined with Ba 2+, Hg 2 2+, Sr 2+, and Pb 2+. Ca 2+ compounds are slightly soluble. 5. Carbonate (CO 3 2– ) and phosphate (PO 4 3– ) compounds are only slightly soluble. 6. Most hydroxide (OH – ) compounds are insoluble except when combined with group 1A cations. Ca(OH) 2 is slightly soluble. –An ionic compound is said to be soluble if a large amount of it dissolves in water. How much is a “large amount”? Typically, this means a solution with a concentration of at least 0.1 mol/L (mole per liter) at room temperature. An insoluble ionic compound is defined as one that will not dissolve in water, typically producing an aqueous solution of less than mol/L at room temperature. A slightly soluble compound falls somewhere between these two boundaries, usually forming a precipitate in water.

Properties of Solution-Solution Formation 1. The effect of temperature a. Increase in the rate of solubility b. The addition of heat cause the solvent molecules to move further apart thereby allowing more solute to come into contact with the solvent molecules. 2. The effect of particle size a. Smaller particles increase the rate of solubility. b. The larger surface area of the numerous particles exposes more solute molecules to the solvent than does the surface area of a single large lump. 3. The effect of stirring a. Increase in the rate of solubility. b. Stirring tends to bring the solute particles into contact with all particles of the solvent.

Volatile and Nonvolatile Notice the word "nonvolatile" in the title. The volatility of a substance refers to the readiness with which it vaporizes. Generally speaking, substances with a boiling point below 100 °C are considered volatile and all others are called nonvolatile. Ethyl alcohol and pentane are examples of volatile substances; sugar and sodium chloride are considered nonvolatile.