WHAT’S IN THE BOTTLE?

An Inquiry Lab

DO NOW Get out lab sheets and logbook

GOAL To determine the type of bonding in

unlabeled chemicals using physical and chemical properties of substances with ionic, molecular, and metallic bonds.

IONIC COMPOUNDS compounds containing a metal and a

nonmetal strong electrostatic attractions between positive and negative ions

formulas given in the simplest ratio of elements

crystalline structures that are solids at room temperature

ions that form a crystal lattice structure. compounds that melt at high temperatures Substances that are good conductors of

electricity in the molten or dissolved state

COVALENT COMPOUNDSnonmetals attracted to other nonmetals formulas that are given in the true ratios

of atoms substances that may exist in any state of

matter at room temperature (solid, liquid, or gas)

compounds that melt at low temperaturessubstances that are nonconductors of

electricity

POLAR VERSUS NONPOLARPolar Covalent - NM/NM or M/NM usually dissolves in water Usually higher in mass than nonpolar

substances More likely to be solids.

Nonpolar Covalent – NM/NM Does not dissolve in water Usually not solids.

METALLIC COMPOUNDSsubstances that are metalsa “sea” of mobile or delocalized electrons

surrounding a positively charged metal centeran attraction between metal ions and

surrounding electrons formulas written as a neutral atom (Mg, Pb)solids with a crystalline structure at room

temperaturea range of melting points—usually depending

on the number of valence electronssubstances that are excellent conductors of

electricity since the electrons in the “sea” are free to move.

SAFETY AND DISPOSAL Safety goggles should be worn at all

times in the laboratory. Be cautious of acidic and basic solutions

since they can cause skin burns and eye damage.

Liquids and solids are to be disposed of in properly labeled waste containers per MSDS guidelines.

Galvanized iron square has sharp edges – handle with care to prevent cuts.

MATERIALS Universal indicator, 0.1M hydrochloric

acid (HCl), 0.1M sodium hydroxide (NaOH), 95 % Ethanol(C2H5OH); Ice, Magnifying lens, micro-scale wellplate, Hexane, Phenolphthalein, Conductivity tester (metals and aqueous only), Distilled water, pH paper, wooden splints, food can lid (iron square), cotton swabs, MSDS for all knowns and unknowns used, toothpicks, magnet, sandpaper, hot plate.

PRELAB PREPARATION You will be given four KNOWN

chemicals (1–10 grams each) in small containers.

The containers are labeled with the name, formula, and CAS number.

You have an MSDS for each compound.

PRELAB GUIDED QUESTIONS1. Review the electronegativities of the

elements. Review electronegativity values and trends using the periodic table.

2. Have a discussion with your lab partner(s) about the type of bonding represented by the chemicals in this lab: nonpolar covalent, polar covalent, ionic, and metallic.

PRELAB GUIDED QUESTIONS

**Replacing Iodine with STEARIC ACID

white solid, MP 67°C, insoluble in water, NM/NM, nonpolar covalent

PRELAB GUIDED QUESTIONS3. Compare the type of bond with regard

to the properties below using Table 1 and explain any relationships. HINT: Think of what is happening between the bonded atoms as well as what occurs between the particles.

a. melting pointb. solubility in 25oC water

4. Predict the properties of each substance below based on Table 1.

PRELAB GUIDED QUESTIONS

PART ONEPractice with Instrumentation and

ProcedureThe purpose of this portion of the lab is to identify properties that allow one to determine the type of bonding in a substance and to carry out tests that allow one to characterize these properties.

PROCEDURE1. Given four known compounds, choose at least four

different tests to study physical and chemical properties of each of the given substances.

2. Based on your results, you will develop a system that will help determine whether an unknown solid is ionic, covalent (polar or nonpolar), or metallic using these tests.

3. Possible tests include: color, solubility in water, conductivity of the solid, conductivity in water, pH of the solution in water, solubility in ethanol, solubility in hexanes, high/low melting point (order of melting if qualitative), reaction with 0.1M HCl, reaction with 0.1M NaOH, and magnetism.

PROCEDURE4. Select at least four tests, quantitative

and qualitative, and write a detailed procedure to carry out the tests.

5. Refer to the Materials section for guidance on available materials.

6. Create a data table to record results.7. Performs tests8. Melting point will be done qualitatively

using a can lid to compare relative melting time.

NEXT Once you finish Part One, turn in the

four film canisters – potassium chloride, sucrose, zinc, and stearic acid.

You will pick up your five unknowns. You are responsible for returning your

unknowns to me each day.

PRACTICE QUESTIONS Answer these for the lab report.

PART TWOThe InvestigationProcedure The knowledge acquired in the Practice section for known

compounds will now be applied in order to determine the type of bond for five unknown solids. Given five unknown compounds, you will choose at least four different tests to study physical and chemical properties of the substances. Based on your results, you will develop a system that will help determine whether an unknown solid is ionic, covalent (polar or nonpolar), or metallic using these tests. Possible tests include color, solubility in water, conductivity of the solid, conductivity in water, pH of the solution in water, solubility in ethanol, solubility in hexanes, high/low melting point (order of melting if qualitative), reaction with 0.1 M HCl, reaction with 0.1 M NaOH, and magnetism.

You should select at least four tests, quantitative and qualitative, and write a detailed procedure to carry out the tests. Refer to the Materials section for guidance on available materials.

DATA COLLECTION AND COMPUTATION

Create a data table to record results. After you have completed your procedure, complete data table. Identify the bond type in each unknown. Using the list of all of the unlabeled bottles (the unknowns), your results, and the MSDS for the unknowns, identify the five chemicals you tested.

CONCLUSIONArgumentation and Documentation Answer the questions that follow.

Post lab Assessment Answer the questions that follow.

WRITING THE LAB REPORT One report per group. includes title page, goal, materials you

used in both parts, prelab guiding question answers, Part One data table, Part One practice question answers, Part Two detailed procedure, Part Two data table, argumentation and documentation question answers, and post lab assessment question answers.

Each partner should initial the part that he/she wrote in the final report.

HELPFUL HINTSEverything you need is at your desk except: Cotton swabs, extra toothpicks, and

extra splints are on the back table. Chemicals on trays on back table are

NOT for this lab. Ice at lab desk #1 Unknowns at lab desk #1. Must turn in

four knowns before getting unknowns. Return unknowns to front desk each day. Unplug hot plate before leaving for the

day.

GET STARTED Wear goggles Get your unknowns from the front. If you need the four knowns from

yesterday, get them from me. Lab materials will be out through

Wednesday. Group lab report is due Friday, Dec. 6.

ADD PART ONE PROCEDURE TO LAB REPORT. NOT LISTED BUT SHOULD BE INCLUDED.

POTENTIAL COMPOUNDSIONIC Ammonium chloride Magnesium oxide Sodium carbonate Sodium hydrogen carbonate Sodium chloride Copper(II) sulfate, anhydrous Potassium nitrate Calcium carbonate Sodium acetateMETALLIC aluminum Iron Copper magnesium

POLAR COVALENT Citric Acid Salicylic acid Sucrose Urea dextrose methylcellulose

NONPOLAR COVALENT wax/paraffin silicon dioxide Agar Lauric acid