Transcript What`s in the Bottle – Web

An Inquiry Lab
 To
determine the type of bonding in
unlabeled chemicals using physical and
chemical properties of substances with ionic,
molecular, and metallic bonds.
 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
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nonmetals 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 temperatures
substances that are nonconductors of
electricity
Polar 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.
substances that are metals
 a “sea” of mobile or delocalized electrons
surrounding a positively charged metal center
 an attraction between metal ions and
surrounding electrons
 formulas written as a neutral atom (Mg, Pb)
 solids with a crystalline structure at room
temperature
 a range of melting points—usually depending
on the number of valence electrons
 substances that are excellent conductors of
electricity since the electrons in the “sea” are
free to move.
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 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.
 #10 food can lid has sharp edges – handle
with care to prevent cuts.
 Universal
indicator, 0.1M hydrochloric acid
(HCl), 0.1M sodium hydroxide (NaOH), 95 %
Ethanol(C2H5OH); Ice, Magnifying lens, microscale wellplate, Hexane, Phenolphthalein,
Conductivity tester (metals and aqueous
only), Distilled water, pH paper, wooden
splints, #10 food can lid, cotton swabs, MSDS
for all knowns and unknowns used,
toothpicks, magnet, sandpaper, hot plate.
 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.
MSDS – Material Safety Data Sheet
 It is intended to provide people with
procedures for handling or working with the
substance in a safe manner, and includes
information such as physical data (melting
point, boiling point, flash point, etc.),
toxicity, health effects, first aid, reactivity,
storage, disposal, protective equipment, and
spill-handling procedures.
 There is one for every compound you are
using at the lab desks.
From Wikipedia
CAS Registry Number
 is an unique numerical identifier assigned by
Chemical Abstracts Service (CAS) to every
chemical substance described in the open
scientific literature (currently including
those described from at least 1957 through
the present), including organic and inorganic
compounds, minerals, isotopes, alloys and
nonstructurable materials (UVCBs, of
unknown, variable composition, or biological
origin).
 Over 81 million compounds have a CAS #.
From Wikipedia
1.
2.
Review the electronegativities of the
elements. Review electronegativity values
and trends using the periodic table.
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.
**Replacing Iodine with STEARIC ACID
white solid, MP 67°C, insoluble in water,
NM/NM, nonpolar covalent
3. 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 point
b.
solubility in 25oC water
4. Predict the properties of each substance
below based on Table 1.
Practice with Instrumentation and Procedure
The 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.
1.
2.
3.
Given four known compounds, choose at least
four different tests to study physical and
chemical properties of each of the given
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 0.1M HCl, reaction with 0.1M
NaOH, and magnetism.
4.
5.
6.
7.
8.
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.
Create a data table to record results.
Perform tests.
Melting point will be done qualitatively
using a can lid to compare relative melting
time.
 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.
 Answer
these for the lab report.
The Investigation
Procedure
 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.
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 the
unknowns, your results, and the MSDS for the
unknowns, identify the five chemicals you
tested.
Argumentation and Documentation
 Answer the questions that follow.
Post lab Assessment
 Answer the questions that follow.
 One
report per group.
 includes title page, goal, materials you used
in both parts, prelab guiding question
answers, Part One detailed procedure, 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.
Everything 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 or in
bottles 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.
IONIC
 ammonium chloride
 magnesium oxide
 sodium carbonate
 sodium hydrogen carbonate
 sodium chloride
 copper(II) sulfate, anhydrous
 potassium nitrate
 calcium carbonate
 sodium acetate
METALLIC
 aluminum
 iron
 copper
 magnesium
POLAR COVALENT
 citric Acid
 salicylic acid
 sucrose
 urea
 dextrose
 methylcellulose
NONPOLAR COVALENT
 paraffin
 silicon dioxide
 agar
 lauric acid