i need pre lab, when i have the data I send to you for the post lab
Determination of the Specific Heat of an Unknown Metal and Heat of Reaction by Hess’s Law
Introduction to Heat, Specific Heat, & Heat of Reaction:
1) Heat (q) can be defined as the flow of energy into and out of a system due to a temperature difference between the thermodynamic system and its surroundings.
2) Heat energy will flow from the region of higher temperature to the region of lower temperature until thermal equilibrium has been reached.
a. At thermal equilibrium, the temperature of the two regions will be equal at any one time.
3) The formula for heat is as follows: q = s ( m ( Δt
a. q = heat, s = specific heat, m = mass, Δt = change in temperature.
i. Specific heat for water = 4.184 J/g ( oC.
b. Specific heat = the quantity of heat required to raise the temperature of one gram of a substance, one degree Celsius (or Kelvin) at constant pressure.
i. Specific heats are characteristic for that substance at 25oC and constant pressure.
Unknown Metal
Specific Heat (J/(g(oC))
Aluminum
0.901
Iron
0.450
Lead
0.128
Copper
0.387
4) In chemical reactions, heat is often transferred from the “system” to its “surroundings,” or vice versa.
a. The substance or mixture of substances under study in which a change occurs is called the thermodynamic system (or just the system.)
b. The surroundings are everything around that thermodynamic system that can interact.
5) The sign of q is very important!
a. If q is positive, heat is absorbed by the system.
i. This process is described as endothermic.
b. If q is negative, heat is released from the system.
i. This process is described as exothermic.
6) The heat of reaction is the value of q required to return a system to the given temperature at the completion of a reaction.
7) The enthalpy of reaction (ΔHrxn) is an extensive property of a system that can be used to obtain the heat absorbed/evolved in a reaction at a given temperature and pressure.
a. If at constant pressure, the qp can be determined from the following formula: ΔHrxn = qp.
Introduction to Hess’s Law:
1) Hess’s law of heat summation states that for a chemical equation that can be written as the sum of two or more steps, the enthalpy change for the overall equation is the sum of the enthalpy changes for the individual steps.
2) Example Calculation:
a. Unknown: 2 CaCO3(s) ( 2 CaO(s) + 2 CO2(g) ΔH = ?
b. Known:
i. Ca(s) + C(s) + 3/2 O2(g) ( CaCO3(s) ΔHo1 = –1208 kJ
ii. C(s) + O2(g) ( CO2(g)
ΔHo2 = – 393.5 kJ
iii. Ca(s) + ½ O2(g) ( CaO(s)
ΔHo3 = – 635.0 kJ
c. Step 1: Flip Equation #1 (and the sign of ΔHo1)
i. CaCO3(s) (Ca(s) + C(s) + 3/2 O2(g) ΔHo1 = –(–1208 kJ)
d. Step 2: Cancel Like Terms and Add ΔHo
i. CaCO3(s) ( Ca(s) + C(s) + 3/2 O2(g)
ΔHo1 = +1208 kJ
ii. C(s) + O2(g) ( CO2(g)
ΔHo2 = –393.5 kJ
iii. Ca(s) + ½ O2(g) ( CaO(s)
ΔHo3 = –635.0 kJ
iv. CaCO3(s) ( CaO(s) + CO2(g)
ΔHorxn = +179.5 kJ
e. Step 3: Multiply by Entire Equation by 2 & ΔHorxn
i. 2
Pre-lab 4
Title: Periodic Trends
Date: 9/12/18
Unknown: N/A
Purpose: The purpose is to observe chemical properties of elements in periods (rows) and in
groups/families (columns).
Balanced Equations:
Part 1: Chemical Properties of the Alkaline Earth Metal Nitrates
Mg(NO3)2(aq) + Na2CO3(aq) MgCO3(s) + 2NaNO3(aq)
Ca(NO3)2(aq) + Na2CO3(aq) CaCO3(s) + 2NaNO3(aq)
Ba(NO3)2(aq) + Na2CO3(aq) BaCO3(s) + 2NaNO3(aq)
Part 2: Chemical Properties of the Halides
NaCl(aq) + AgNO3(aq) AgCl(s) + NaNO3(aq)
NaBr(aq) + AgNO3(aq) AgBr(s) + NaNO3(aq)
NaI(aq) + AgNO3(aq) AgI(s) + NaNO3(aq)
Part 3: Reactivity of Third Period Elements with Oxygen
2 Mg(s) + O2(g) 2 MgO(s)
4 Al(s) + 3 O2(g) 2 Al2O3(s)
Si(s) + O2(g) SiO2(s)
Part 4: Reactivity of Third Period Elements with Hydrochloric Acid
Mg(s) + 2 HCl(aq) MgCl2(aq) + H2(g)
2 Al(s) + 6 HCl(aq) 2 AlCl3(aq) + 3 H2(g)
Si(s) + 4 HCl(aq) SiCl4(aq) + 2 H2(g)
Table of Chemical and Physical Properties:
Chemical Name Molecular
Weight
Boiling Point Density Safety
Barium nitrate
Ba(NO3)2
261.34
529 C 3.24 g/cm
3 Poisonous. Do
not mix with
flammable
materials.
Silver nitrate
AgNO3
169.87 440 C 4.35 g/cm
3 Corrosive and
toxic. Avoid
skin contact.
Sodium Chloride
NaCl
58.44 801 C (melting
point)
2.16 g/cm3 Nonhazardous
Magnesium
Mg
24.31 650 C (melting
point)
1.738 g/cm3 Flammable. Do
not stare are
flame during
reaction with
magnesium and
oxygen
Calcium
Ca
40.08 842 C (melting
point)
1.54 g/cm3 Flammable
gases produced
with in contact
with water
Aluminum
Al
26.98 2460 C 2.7 g/cm
3 Flammable
Silicon
Si
28.09 2355 C 2.33 g/ml Nonhazardous
Oxygen
O
15.999 u 90.188 K 1.429 g/L Flammable gas
Hydrochloric
acid
HCl
36.46 110 C 1.18 g/cm
3 Toxic and
corrosive. Can
cause irritation
or burns to skin.
Procedure Observation
Part 1
1. Add 1ml of each solution to each
labeled test tubes
2. Add about three drops of solution
from tube 4 into tubes 1-3 and record
observations.
Part 2
3. Repeat steps 1&2 for part 2 with
different solutions
Part 3
4. On a watch glass, add small pieces of
magnesium, aluminum and silicon and
observe physical appearances.
5. Take turns placing each substance
over an open flame and record
observations.
Part 4
6. Place a small piece of magnesium,
aluminum, and silicon in separate test
tubes and label appropriately.
7. Place 1ml of HCl into each test tube
and record observations.
Data Collected:
Part 1
Aqueous
substances
Observations after reacting with 0.02 M Na2CO3
Mg(NO3)2
Ca(NO3)2
Ba(NO3)2
Part 2
Aqueous
substances
Observations after reacting with 0.10 M AgNO3
NaCl
NaBr
NaI
Part 3
Metallic
substances
Observations during and after reaction with atmospheric O2
Mg
Al
Si
Part 4
Metallic
substa
Pre-lab 4
Title: Periodic Trends
Date: 9/12/18
Unknown: N/A
Purpose: The purpose is to observe chemical properties of elements in periods (rows) and in
groups/families (columns).
Balanced Equations:
Part 1: Chemical Properties of the Alkaline Earth Metal Nitrates
Mg(NO3)2(aq) + Na2CO3(aq) MgCO3(s) + 2NaNO3(aq)
Ca(NO3)2(aq) + Na2CO3(aq) CaCO3(s) + 2NaNO3(aq)
Ba(NO3)2(aq) + Na2CO3(aq) BaCO3(s) + 2NaNO3(aq)
Part 2: Chemical Properties of the Halides
NaCl(aq) + AgNO3(aq) AgCl(s) + NaNO3(aq)
NaBr(aq) + AgNO3(aq) AgBr(s) + NaNO3(aq)
NaI(aq) + AgNO3(aq) AgI(s) + NaNO3(aq)
Part 3: Reactivity of Third Period Elements with Oxygen
2 Mg(s) + O2(g) 2 MgO(s)
4 Al(s) + 3 O2(g) 2 Al2O3(s)
Si(s) + O2(g) SiO2(s)
Part 4: Reactivity of Third Period Elements with Hydrochloric Acid
Mg(s) + 2 HCl(aq) MgCl2(aq) + H2(g)
2 Al(s) + 6 HCl(aq) 2 AlCl3(aq) + 3 H2(g)
Si(s) + 4 HCl(aq) SiCl4(aq) + 2 H2(g)
Table of Chemical and Physical Properties:
Chemical Name Molecular
Weight
Boiling Point Density Safety
Barium nitrate
Ba(NO3)2
261.34
529 C 3.24 g/cm
3 Poisonous. Do
not mix with
flammable
materials.
Silver nitrate
AgNO3
169.87 440 C 4.35 g/cm
3 Corrosive and
toxic. Avoid
skin contact.
Sodium Chloride
NaCl
58.44 801 C (melting
point)
2.16 g/cm3 Nonhazardous
Magnesium
Mg
24.31 650 C (melting
point)
1.738 g/cm3 Flammable. Do
not stare are
flame during
reaction with
magnesium and
oxygen
Calcium
Ca
40.08 842 C (melting
point)
1.54 g/cm3 Flammable
gases produced
with in contact
with water
Aluminum
Al
26.98 2460 C 2.7 g/cm
3 Flammable
Silicon
Si
28.09 2355 C 2.33 g/ml Nonhazardous
Oxygen
O
15.999 u 90.188 K 1.429 g/L Flammable gas
Hydrochloric
acid
HCl
36.46 110 C 1.18 g/cm
3 Toxic and
corrosive. Can
cause irritation
or burns to skin.
Procedure Observation
Part 1
1. Add 1ml of each solution to each
labeled test tubes
2. Add about three drops of solution
from tube 4 into tubes 1-3 and record
observations.
Part 2
3. Repeat steps 1&2 for part 2 with
different solutions
Part 3
4. On a watch glass, add small pieces of
magnesium, aluminum and silicon and
observe physical appearances.
5. Take turns placing each substance
over an open flame and record
observations.
Part 4
6. Place a small piece of magnesium,
aluminum, and silicon in separate test
tubes and label appropriately.
7. Place 1ml of HCl into each test tube
and record observations.
All observations are documented in the data
tables below
Data Collected:
Part 1
Aqueous
substances
Observations after reacting with 0.02 M Na2CO3
Mg(NO3)2 No physical change observed
Ca(NO3)2 Semi-solid, cloudy substance formed and sunk to the bottom of the test tube
Ba(NO3)2 Solution became milky and slowly sunk to the bottom
Part 2
Aqueous
substances
Ob
Banerjee
The lab notebook guidelines are included in this document.
1. Each lab period, in addition to coming to lab properly dressed, a pre-lab must be
prepared for the lab you are scheduled to perform that day. Failure to come to lab
without a complete pre-lab and improper dress will result in dismissal from the week’s
lab with a zero point allocation.
a. Each pre-lab should include the following sections: Name, Title, Date, Unknown,
Purpose, Balanced Equations, Table of Chemical and Physical Properties,
Procedure and an incomplete data table under Data Collected. This should be
uploaded on CANVAS before the start of lab and will be scanned for plagiarism.
This is due at the beginning of the lab period (mandatory).
2. Do not leave without checking out with your professor. You are allowed to use any
notebook or electronic notebook for this lab. Binded lab notebook is not needed for this
lab.
3. Lab reports (post-lab) are due 1 week following the completion of a lab. Each lab is
worth 100 points, comprising of pre and post lab. Your professor will provide further
instructions for completing your lab report.
a. Reports that are suspected to be plagiarized will be reported to the Dean, as
potential violators of the Academic Dishonesty guidelines (procedure 5026). This
will result in an F in the class. Self-plagiarism is also considered plagiarism.
4. The final lab report (post-lab) should comprise of 1) pre-lab sections, 2) Data collected,
3) Observations, 4) Discussion and 5) Conclusion and should be uploaded to CANVAS
placeholder.
Please upload at correct placeholder for each lab. Resubmissions are not allowed.
Please keep an eye on similarity score after submission.
Banerjee
Laboratory Notebook Guidelines
A proper laboratory notebook is one from which a given laboratory experiment can be repeated
by another chemist. Another chemist, chemical engineer or chemical patent lawyer should be
able to read your notebook and understand what you did and the results you obtained.
1. Every experiment should include the following sections listed below.
Title
Name
Date
Unknown (if any)
Purpose Describe the goal of the experiment.
Balanced Equation(s) (if any)
Table of Chemical and Physical Properties (including reference information, if
necessary)
Procedure & Do not provide a detailed, step-by-step procedure. The procedure is in
numerical form and should give the reader a general description of the procedure and any
special experimental details.
Observations . Throughout the lab, be sure to include any relevant observations: What
mass or volume did YOU use? Was the product a solid, liquid, gel, red precipitate, green
solution, etc?
Data Collected A sample data table is provided in each lab write-up. Record the
quantities of materials you used in the experiment. This includes calculations using
formulas, perc
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