Ionic and Covalent Substances Experiment # 8 H2OH2O NaCl Na 1+ Cl 1- Na 1+

Purpose of Lab: Purpose: - To observe the physical properties of ionic and molecular compounds.

Solute – what is being dissolved Solvent – what is doing the dissolving Ex: water and ice tea mix Solute – ice tea mix Solvent – water Solute Vs. Solvent

Solubility

Ionic Compounds – An atom transfers electron(s) to another atom. Molecular Compounds – Atoms share electrons between them. Compounds based on the type of bonding

Physical Properties Ionic compounds – – solid at room temperature –Have higher melting points –Electrolytes –Most ionic compounds dissolve in water due to the charges of the ions interacting with the charged poles of the water molecule –Will not dissolve in Non-polar solvents Covalent compounds – –gases at room temperature –Have lower points –Non-Electrolytes

Ionic Compounds Ionic (polar) bonds + and - side Large difference in electronegativity Na + + Cl - → NaCl Difference in the electronegativites is between 3.3 – 2.0 Involves complete transfer of electrons (Strong bond). This large difference in electronegativity, is result of the compound containing a metal and non-metal.

Two different non-metals O-C-O = CO 2 Molecular Compounds Covalent Bonds 2 types Non-Polar No difference in electronegativity Polar Covalent slight difference in electronegativity; between 1.9 – 0.90 Equal sharing of electrons in bond (Strong bond). bonds between diatomic elements Br-Br = Br 2

H2OH2O C 6 H 22 O 11 H2OH2O NaCl Na 1+ Cl 1- Na 1+ Breaks down into ions Does not break down What happens in water?? CHO

Why does this happen? Water is polar covalent. The Oxygen atom is slightly negative and the Hydrogen atoms are slightly positive. This is from their respective electronegativites. This slight positive and negative are NOT CHARGES MORE LIKE POLES like on a battery. The slightly positive H + attracts the negative Cl - O-O- H+H+ H+H+ + NaCl → H + Cl - Na + O - The slightly negative O - attracts the positive Na +1

Emulsifiers They are comprised of both polar and non-polar segments. They have the capacity to dissolve in both polar and non-polar solvents. Soaps and detergents are examples. One part of the molecule is hydrophobic (does not like water) and one part is hydrophilic (likes water) This is what allows soap to wash our dirty dishes /clothes. Observe Demo and record results on pg 119 # 4

Chromatography- developed by a Russian scientist who wanted to know what happened the pigments that leaves contain that are hidden unit fall. This process can be used to separate any color or product. Chromatography pg 116 &120

The initial color will separate and you will be able to determine the colors that make up the initial color. we measure the distance the any of the secondary colors travel on the paper. We can compare the distance the color travels to the distance the solvent travels. This measurement is called R f factor. Have you ever see a bottle of food dye. Ex Blue # 7. Observe Demo and record results on pg 120

Due Next Week Page 117 #1 A-L # 2 Page # 119 #3 A-F # 4 Page #121 Questions 1-4