Thermo-Chemistry Calculations discussion


Thermo-Chemistry Calculations

Don't use plagiarized sources. Get Your Custom Essay on
Thermo-Chemistry Calculations discussion
Just from $10/Page
Order Essay

Data Sheet


  Avg (°C) Absolute Uncertainty Relative uncertainty
T1 21.1 0.2 0.95%
T2 40.5 0.2 0.49%
T3 31.6 0.2 0.63%
T4 21.15 0.2 0.95%
T5 26.35 0.2 0.76%
T6 21.9 0.2 0.91%
T7 18.85 0.2 1.06%



Average temperatures (°C)

T1= (21.2+21.0)/2= 21.1

Absolute Uncertainty= (0.1+0.1) = 0.2

21.1°C± 0.2 °C

Relative Uncertainty= (0.2/21.1)*100%= 0.95%

T2= (40.1+40.0)/2= 40.5°C

Absolute Uncertainty= 0.2

40.5 °C ±0.2 °C

Relative Uncertainty= (0.2/40.5)*100%= 0.49%

T3= (31.6+31.6)/2= 31.6

Absolute Uncertainty= (0.1+0.1) = 0.2

31.6 °C ± 0.2 °C

Relative Uncertainty= (0.2/31.6)*100%= 0.63%

T4= (21.20+ 21.10)/2= 21.15 °C

Absolute Uncertainty= 0.2

21.15 °C±0.2 °C

Relative Uncertainty= (0.2/21.15)*100%= 0.95%

T5= (26.30+26.40)/2= 26.35 °C

Absolute Uncertainty= (0.1+0.1) = 0.2

26.35°C±0.2 °C

Relative Uncertainty= (0.2/26.35)*100%= 0.76%

T6= (22.0+21.8)/2= 21.9 °C

Absolute uncertainty= (0.1+0.1) = 0.2

21.9°C± 0.2°C

Relative Uncertainty= (0.2/21.9)*100%= 0.91%

T7= (18.80+18.90)/2= 18.85 °C

Absolute Uncertainty= (0.1+0.1) = 0.2

18.85°C±0.2 °C

Relative Uncertainty= (0.2/18.85)*100= 1.06%


Part C


Avg mass in grams                  Absolute Uncertainty                          Relative Uncertainty

4.9906                                     0.0004                                                 0.01%


Avg mass= (4.9908+4.9904)/2 = 4.9906g

Absolute Uncertainty= (5.0000-4.9906) g= 0.0004g

Relative Uncertainty= (0.0004/5)*100= 0.01%

Report Sheet


Moles of NH4Cl         

Moles= mass/RMM

RMM= 14+4+35.5= 53.5

4.9906/53.5= 0.0933moles

Avg moles=0.0933moles

The number of moles when 5g of the NH4Cl was used

5/53.5= 0.0935moles

Absolute uncertainty= (0.0935-0.0933) = 0.0002

Relative uncertainty= (0.0002/0.0935)*100%


Moles of Water (moles of cold water= moles of hot water)

Mass of water= volume*density

=50.00cm3*1g/cm3= 50.00g

Moles=mass/RMM= 50.00g/18= 2.78moles

Absolute uncertainty according to the instructions is 0.5

Therefore, relative uncertainty= (0.5/2.78)*100%= 17.99%


2.78*75.31(31.6-21.1) +2.78*75.31*(31.6-40.5) +Ccal (31.6-21.1) =0




Absolute Uncertainty= 0.2+0.2+0.2+0.2+0.2+0.2= 1.2

Relative uncertainty= (1.2/31.9)*100%= 3.76%


Moles of 1M NH4OH



NH4OH (aq) +HCl (aq) =NH4Cl (aq) +H2O (l)

Mole ratio= 1:1

Moles of water=0.05moles

Absolute uncertainty= 0.5

Relative uncertainty= (0.5*0.05)*100%= 2.5%

ΔH2+nCp (T5-T4) +Ccal (T5-T4) =0

ΔH2+0.05*72.72(26.35-21.15) + -31.90(26.35-21.15) =0




Absolute uncertainty=2.0

Relative uncertainty= (2.0/146.97)*100%= 1.36%

Molar enthalpy=146.97/0.05


Absolute uncertainty= 1.2+4(0.2) = 2.0

Relative uncertainty= (2/2939.4)*100% =0.0068%

ΔH3+nCp (T7-T6) +Ccal (T7-T6) =0

ΔH3+0.0933*70.74(18.85-21.9)-31.90(18.85-21.9) =0



Absolute uncertainty=2.0

Relative uncertainty= (2.0/51.865)*100%= 3.86%

Molar enthalpy= -51.865/0.0933


Absolute uncertainty=2.0

Relative uncertainty= (2/555.9)*100%=



  value units (±) absolute uncertainty (±) relative uncertainty %
Mole H2O (50mL) 2.78 moles 0.5 17.99
B mole NH4Cl(aq) 0.05 moles 0.5 2.5
C mole NH4Cl(S) 0.0933 mole 0.0002 0.21
Ccal-Avg -31.90 J./K 1.2 3.76
ΔH2-avg +146.97


J/K 2.0 1.36
ΔH2-avg /mole NH4Cl +2939. 4 Jmol-1K


2.0 0.0068
ΔH3-avg 51.865 J/K 2.0 3.86
ΔH3-avg/mole NH4Cl -555.9 Jmol-1K


2.0 0.36



ΔH1: Ʃ (nΔHf (products) -Ʃ (nΔHf (reactants) = ΔH1

NH4OH (aq) +HCl (aq) = NH4Cl (s) +H2O (l)

NH4OH (aq) +HCl (aq) = NH4Cl (aq) +H2O (l)

NH4Cl (s) = NH4Cl (aq)

Using Hess’s Law, rearrange reaction (2) and (3) and demonstrate how they can be used to calculate ΔH1

The expected equation should be:

NH4OH (aq) +HCl (aq) = NH4Cl (s) +H2O (l)

Rearranging equations to come out with the above equation

NH4OH (aq) +HCl (aq) = NH4Cl (aq) +H2O (l)Reaction (1)

NH4Cl (aq)= NH4Cl (s)                                                     Reaction (2)

From the above arrangement of reactions (1) and (2), we can obtain desired final equation after cancellation of NH4Cl (aq)from the product side of equation (1) and the same product from the left side of equation (2). For one to obtain reaction (2) as written above, the initial reaction, NH4Cl (s) = NH4Cl (aq), must be reversed to obtain NH4Cl (aq)= NH4Cl (s). Therefore, the enthalpy of formation of NH4Cl (s)changes from -314.55 Jmol-1K to + 314.55Jmol-1K. After the equation is reversed, it is possible to eliminate the NH4Cl (aq)particles to obtain the final equation. The final desired equation is NH4OH (aq) +HCl (aq) = NH4Cl (s) +H2O (l).

nΔHf (products) = (314.55-285.83) Jmol-1K

=+28.72 Jmol-1K

nΔHf (reactants) = (-366.25-167.16) Jmol-1K

=-533.41 Jmol-1K

ΔH1= 28.72- (-533.41) = +562.13 Jmol-1K

Absolute uncertainty = (0.005*4) = 0.02

Relative uncertainty = (0.02/562.13)*100% = 0.000036%

Can we carry out reaction (1) experimentally? Explain your reasoning.

According to the results presented (+562.13 Jmol-1K), we can carry out the experiment, NH4OH (aq) +HCl (aq) = NH4Cl (aq) +H2O (l) experimentally since it requires less activation energy for the reaction to start. Therefore, so long as the reactants are heated to provide the necessary energy, the reaction occurs. Besides, one can use a suitable catalyst to change the path of reaction, reducing the activation energy, initiating the reaction.

ΔH1 = ΔH2+ ΔH3

ΔH2 =+2939.4 Jmol-1K

ΔH3 = -555.9 Jmol-1K

ΔH1= (2939. 4- 555.9) Jmol-1K

ΔH1 = +2383.5 Jmol-1K

Absolute uncertainty= 2.0+2.0= 4.0

Relative uncertainty= (4/2383.5)*100%= 0.168%

  value units (±) absolute uncertainty (±) relative uncertainty %
ΔH1 +562.13 Jmol-1K 0.02 0.000036%
ΔH2-avg /mole NH4Cl + ΔH3-avg /mole NH4Cl +2383.5 Jmol-1K 4.0 0.168%

Was Hess’s Law obeyed (within experimental uncertainty) based on your own data and calculations? Give a brief explanation of your reasoning.

The Hess’s Law states that, regardless of the several steps of a reaction, the total change of enthalpy for the chemical reaction is the addition of all changes. Consequently, at constant pressure, the heat of reaction, enthalpy change in a reaction, is independent of the root between the last and the primary states. Comparing the calculated and experimental results for ΔH1, and the uncertainties between the two values, Hess Law was not obeyed since the two enthalpies are different. Calculated enthalpy of formation of NH4Cl is + 562.13 Jmol-1K. Contrarily, the experimental enthalpy of formation of NH4Cl is +2383.5 Jmol-1K. Besides, the absolute uncertainty of calculated enthalpy of formation of NH4Cl is ± 0.02, while the absolute uncertainty of experimental enthalpy of formation of NH4Cl is± 0.4. Similarly, the relative uncertainty of calculated enthalpy of formation of NH4Cl is ± 0.000036%, while the relative uncertainty of experimental enthalpy of formation of NH4Cl is ± 0.168%.

Suggest a reason why you are instructed to use ± 0.5mL as the uncertainty in the 50 mL volumes rather than ±0.05mL, which is the uncertainty of a 50 mL pipette or dispensator.

Other measurements, such as temperature, are to be recorded to one decimal place. For instance, according to the instructions, temperatures are to be measured to the nearest 0.1°C. For this reason, it is recommended for other readings to take the same form to enhance uniformity. Besides, the instruments may not be accurate because of their age; therefore, it is advisable for one to use the uncertainty of ± 0.5ml.

In conclusion, the experimental outcomes defied the calculated results because when ΔH1 for the two procedures are compared, different results are obtained. For instance, Hess’s Law is not obeyed in the experiment. The reason for the difference in the outcomes can be because of errors in volume measurements and temperature readings. Besides, it could be because of the rapid loss of heat into the surrounding, reducing the thermometer readings making inaccurate measurements to be used in the calculation.




Get Professional Assignment Help Cheaply

Buy Custom Essay

Are you busy and do not have time to handle your assignment? Are you scared that your paper will not make the grade? Do you have responsibilities that may hinder you from turning in your assignment on time? Are you tired and can barely handle your assignment? Are your grades inconsistent?

Whichever your reason is, it is valid! You can get professional academic help from our service at affordable rates. We have a team of professional academic writers who can handle all your assignments.

Why Choose Our Academic Writing Service?

  • Plagiarism free papers
  • Timely delivery
  • Any deadline
  • Skilled, Experienced Native English Writers
  • Subject-relevant academic writer
  • Adherence to paper instructions
  • Ability to tackle bulk assignments
  • Reasonable prices
  • 24/7 Customer Support
  • Get superb grades consistently

Online Academic Help With Different Subjects


Students barely have time to read. We got you! Have your literature essay or book review written without having the hassle of reading the book. You can get your literature paper custom-written for you by our literature specialists.


Do you struggle with finance? No need to torture yourself if finance is not your cup of tea. You can order your finance paper from our academic writing service and get 100% original work from competent finance experts.

Computer science

Computer science is a tough subject. Fortunately, our computer science experts are up to the match. No need to stress and have sleepless nights. Our academic writers will tackle all your computer science assignments and deliver them on time. Let us handle all your python, java, ruby, JavaScript, php , C+ assignments!


While psychology may be an interesting subject, you may lack sufficient time to handle your assignments. Don’t despair; by using our academic writing service, you can be assured of perfect grades. Moreover, your grades will be consistent.


Engineering is quite a demanding subject. Students face a lot of pressure and barely have enough time to do what they love to do. Our academic writing service got you covered! Our engineering specialists follow the paper instructions and ensure timely delivery of the paper.


In the nursing course, you may have difficulties with literature reviews, annotated bibliographies, critical essays, and other assignments. Our nursing assignment writers will offer you professional nursing paper help at low prices.


Truth be told, sociology papers can be quite exhausting. Our academic writing service relieves you of fatigue, pressure, and stress. You can relax and have peace of mind as our academic writers handle your sociology assignment.


We take pride in having some of the best business writers in the industry. Our business writers have a lot of experience in the field. They are reliable, and you can be assured of a high-grade paper. They are able to handle business papers of any subject, length, deadline, and difficulty!


We boast of having some of the most experienced statistics experts in the industry. Our statistics experts have diverse skills, expertise, and knowledge to handle any kind of assignment. They have access to all kinds of software to get your assignment done.


Writing a law essay may prove to be an insurmountable obstacle, especially when you need to know the peculiarities of the legislative framework. Take advantage of our top-notch law specialists and get superb grades and 100% satisfaction.

What discipline/subjects do you deal in?

We have highlighted some of the most popular subjects we handle above. Those are just a tip of the iceberg. We deal in all academic disciplines since our writers are as diverse. They have been drawn from across all disciplines, and orders are assigned to those writers believed to be the best in the field. In a nutshell, there is no task we cannot handle; all you need to do is place your order with us. As long as your instructions are clear, just trust we shall deliver irrespective of the discipline.

Are your writers competent enough to handle my paper?

Our essay writers are graduates with bachelor's, masters, Ph.D., and doctorate degrees in various subjects. The minimum requirement to be an essay writer with our essay writing service is to have a college degree. All our academic writers have a minimum of two years of academic writing. We have a stringent recruitment process to ensure that we get only the most competent essay writers in the industry. We also ensure that the writers are handsomely compensated for their value. The majority of our writers are native English speakers. As such, the fluency of language and grammar is impeccable.

What if I don’t like the paper?

There is a very low likelihood that you won’t like the paper.

Reasons being:

  • When assigning your order, we match the paper’s discipline with the writer’s field/specialization. Since all our writers are graduates, we match the paper’s subject with the field the writer studied. For instance, if it’s a nursing paper, only a nursing graduate and writer will handle it. Furthermore, all our writers have academic writing experience and top-notch research skills.
  • We have a quality assurance that reviews the paper before it gets to you. As such, we ensure that you get a paper that meets the required standard and will most definitely make the grade.

In the event that you don’t like your paper:

  • The writer will revise the paper up to your pleasing. You have unlimited revisions. You simply need to highlight what specifically you don’t like about the paper, and the writer will make the amendments. The paper will be revised until you are satisfied. Revisions are free of charge
  • We will have a different writer write the paper from scratch.
  • Last resort, if the above does not work, we will refund your money.

Will the professor find out I didn’t write the paper myself?

Not at all. All papers are written from scratch. There is no way your tutor or instructor will realize that you did not write the paper yourself. In fact, we recommend using our assignment help services for consistent results.

What if the paper is plagiarized?

We check all papers for plagiarism before we submit them. We use powerful plagiarism checking software such as SafeAssign, LopesWrite, and Turnitin. We also upload the plagiarism report so that you can review it. We understand that plagiarism is academic suicide. We would not take the risk of submitting plagiarized work and jeopardize your academic journey. Furthermore, we do not sell or use prewritten papers, and each paper is written from scratch.

When will I get my paper?

You determine when you get the paper by setting the deadline when placing the order. All papers are delivered within the deadline. We are well aware that we operate in a time-sensitive industry. As such, we have laid out strategies to ensure that the client receives the paper on time and they never miss the deadline. We understand that papers that are submitted late have some points deducted. We do not want you to miss any points due to late submission. We work on beating deadlines by huge margins in order to ensure that you have ample time to review the paper before you submit it.

Will anyone find out that I used your services?

We have a privacy and confidentiality policy that guides our work. We NEVER share any customer information with third parties. Noone will ever know that you used our assignment help services. It’s only between you and us. We are bound by our policies to protect the customer’s identity and information. All your information, such as your names, phone number, email, order information, and so on, are protected. We have robust security systems that ensure that your data is protected. Hacking our systems is close to impossible, and it has never happened.

How our Assignment  Help Service Works

1.      Place an order

You fill all the paper instructions in the order form. Make sure you include all the helpful materials so that our academic writers can deliver the perfect paper. It will also help to eliminate unnecessary revisions.

2.      Pay for the order

Proceed to pay for the paper so that it can be assigned to one of our expert academic writers. The paper subject is matched with the writer’s area of specialization.

3.      Track the progress

You communicate with the writer and know about the progress of the paper. The client can ask the writer for drafts of the paper. The client can upload extra material and include additional instructions from the lecturer. Receive a paper.

4.      Download the paper

The paper is sent to your email and uploaded to your personal account. You also get a plagiarism report attached to your paper.

smile and order essaysmile and order essay PLACE THIS ORDER OR A SIMILAR ORDER WITH US TODAY!!!

order custom essay paper