5 Steps to a 5 AP Chemistry 2019

292 ❯ STEP 4. Review the Knowledge You Need to Score High

chemical tests to determine the bonding type. These tests might include melting point,

conductivity, solubility, etc. along with observations of physical properties such as luster

and hardness.

Equipment

Assorted solids—ionic, covalent, metals

Assorted solvents—polar and nonpolar

Conductivity tester

pH paper

Thermometer

Assorted glassware

Measurements

A number of measurements and observations may be made:

Luster: Metals tend to have a metallic luster; solid nonmetals often have a dull luster.

Melting point: Ionic solids and metals have high melting points; covalent compounds have

lower melting points.

Solubility: Ionic compounds and polar covalent solids are generally soluble in water;

metals and nonpolar covalent solids are generally insoluble or very slightly soluble in water.

Conductivity: Aqueous solutions of ionic compounds are conductors; aqueous solutions

of most polar covalent compounds are nonconductors.

Calculations

There are generally no calculations associated with this experiment.

Comments

Many other tests could be used: pH of the aqueous solutions, solubility on organic solvents,

and so on.

Experiment 7: Stoichiometry

Synopsis

In this experiment, you are asked to verify the results of an experiment by checking both the

stoichiometric calculations and the procedure. You will be asked to determine the percent

by mass of substances such as sodium bicarbonate in a mixture. You will do this by making

use of the unique properties of the components in this mixture.

Equipment

Bunsen burners and strikers

Digital balances

Ring stands and rings

Ceramic triangles

Crucibles and lids

Assorted glassware, including volumetric glassware

Measurements

A weighed sample mixture of sodium bicarbonate and sodium carbonate is heated to con-

stant mass. The sodium bicarbonate decomposes to sodium carbonate, carbon dioxide (gas),