Reviewing Chemistry Diploma Questions to Prepare for Exam

[Invisible]

In my Chemistry class we are doing some old diploma review questions in order to prepare for this year's Chemistry diploma. I have answered almost all of the questions.

It says:

The above apparatus (I'll explain the diagram later) was used to determine experimentally the molar enthalpy of the combustionm of candle wax, C25H52(s) (I don't know how to do subscripts).

Questions:

a. List all the measurements that must be taken in order to determine the molar enthalpy of combustion.

- I finished this part...this was pretty easy.

b. Write a mathematical equation that uses the data collected and that will allow you to detrmine the molar heat of combustion. Label each of the mathematical variables used in the equation.

- I finished this part too...not hard at all.

c. Suggest two improvements to the experimental design.

- I've always been really bad at answering these type of questions, maybe because I'm not a conceptual person...

The diagram is just a picture of a calorimeter made out of a solid copper container. The container has a lid on with a thermomenter sticking out of it. Inside the container is liquid water, and the container is being heated with the wax candle. I'm not sure how I could improve the experimental design...

 

[Q_Goest]

- What is ACTUALLY being heated? The water, the copper container, the air inside the container, the atmosphere, even the thermometer... each part of the system is warming up, so to do an accurate calculation, the warming of each part must be taken into consideration, even the candle wax itself as it melts.

So how could we ONLY test for the heat generated by the burning candle wax? Note that even the nitrogen in the air supporting combustion affects the overall calculation.

 

[wais]

First of all, great job on completing the review questions and being proactive in preparing for your Chemistry diploma exam! It's always a good idea to review past questions and practice applying your knowledge.

To answer question c, there are a few improvements that could be made to the experimental design. Here are two suggestions:

1. Increase the precision of the measurements: In order to get a more accurate value for the molar enthalpy of combustion, it's important to take precise measurements. This could include using more precise instruments, such as a digital thermometer instead of a traditional one, or using a more sensitive balance to measure the mass of the candle wax.

2. Control for external factors: During the experiment, it's important to control for any external factors that may affect the results. For example, the room temperature and humidity could affect the rate of combustion and the temperature change of the water. To improve the experimental design, you could conduct the experiment in a controlled environment, such as a temperature-controlled room, and repeat the experiment multiple times to ensure consistent results.

Overall, it's important to always consider ways to improve an experimental design in order to obtain more accurate and reliable results. Keep up the good work and good luck on your exam!