0.10 Bonding 07  (Page 2/3)

ACIDS are molecular compounds which ionize (turn into ions) in water. The cation that is formed is always $H^{+}$ . Therefore, in the formulas for simple acids, H is always the first element listed. Some acids are strong electrolytes and some acids are weak electrolytes. There are no acids which are nonelectrolytes because by definition an acid is a $H^{+}$ donor.

BASES can be molecular compounds or ionic compounds. Some bases are soluble and some are not. The soluble bases ionize or dissociate into ions in water, and the anion formed is always ${\text{OH}}^{-}$ . The ionic bases have hydroxide ( ${\text{OH}}^{-}$ ) as the anion. If they are soluble, the ions simply separate (dissociate) in the water. All of the ionic bases which are soluble are strong electrolytes. 

SALTS are ionic compounds which are not acids or bases. In other words, the cation is not hydrogen and the anion is not hydroxide. Some salts are soluble in water and some are not. All of the salts which are soluble are relatively strong electrolytes.

NONELECTROLYTES are compounds which dissolve in water but do not ionize or dissociate into ions. These would be molecular compounds other than the acids or bases already discussed.

Experimental procedure

Caution:Acids and bases are corrosive and can cause burns.

Part i. predicting bond type through electronegativity differences.

Using the electronegativity table provided in the lab manual, predict the type of bond that each of the following compounds will have by the following process:

• Find the electronegativity for each element or ion in compound using electronegativity table provided.
• Subtract the electronegativites (using absolute value).
• If values are between:

4.0-1.7---Ionic bond-50-100% ionic

1.7-0.3---Polar Covalent bond-5-50% ionic

0.3-0.0---Non-Polar Covalent-0-5% ionic

Determine the type of bonding in the following compounds: KCl, CO, ${\text{CaBr}}_2$ , ${\text{SiH}}_4$ , MgS.

Part ii. weak and strong electrolytes

Chemicals

• tap water
• 0.1 M hydrochloric acid, HCl
• 0.1 M acetic acid, ${\text{HC}}_2{H}_3{O}_2$
• 0.1 M sulfuric acid, $H_2{\text{SO}}_4$
• 0.1 M sodium hydroxide, NaOH
• 0.1 M ammonia, ${\text{NH}}_3$
• 0.1 M sodium acetate, ${\text{NaC}}_2{H}_3{O}_2$
• 0.1 M sodium chloride, NaCl
• 0.1 M ammonium acetate, ${\text{NH}}_4{C}_2{H}_3{O}_2$
• 0.1 M ammonium chloride, ${\text{NH}}_4\text{Cl}$
• methanol, ${\text{CH}}_3\text{OH}$
• ethanol, $C_2{H}_5\text{OH}$
• sucrose solution, $C_{\text{12}}{H}_{\text{22}}{O}_{\text{11}}$

In today’s lab, you will be using a MicroLab conductivity probe to determine how well electrons flow through a given solution. First, you will need to calibrate the probe with a non-electrolyte (distilled water) and a very strong electrolyte. To quantify how well a solution conducts, we will assign numerical values to the conductance probe. A non-conducting solution will have a conductance value of 0, a poor conducting solution will have a reading of 0 to 1,000, and good conductors will have readings of 3,000 up.

Instructions for microlab conductivity experiment

Open the MicroLab Program by clicking on the Shortcut to MicroLab.exe tab on the desktop.

On the“Choose an Experiment Type”Tab, enter a name for the experiment, and then double click on the MicroLab Experiment icon

Click“Add Sensor”, Choose sensor = Conductivity Probe