Endothermic reaction

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Huzaifaf
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Which vein is nearest to the surface of skin?

Post by Huzaifaf »

Which vein carrying blood is nearest to the surface of skin?
Huzaifaf
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Endothermic reaction

Post by Huzaifaf »

I read on a site that during a reaction between 1/2 tea spoon baking powder and 10 ml vinegar, the temperature of the container drops by approximately 7 C. If I increase the quantities of the reactants by 5 times, will the tempearture decreased will also become approximately 35 C ?
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Re: Endothermic reaction

Post by MadelineB »

Hello Huzaifaf and welcome to Science Buddies,

Firstly, I see that you have posted two questions to this forum which seem related. It will be easier for the experts to help you if you keep all of your posts together in the same thread. I've asked one of the moderators to combine your two questions.

Secondly, would you describe the science project which you are working on? This will also help us help you!
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Re: Which vein is nearest to the surface of skin?

Post by MadelineB »

Hello Huzaifaf,
I see that you have also posted questions in the Grades 9-12 Physical Sciences forum. I wonder if this question relates to your other questions? Or is this question related to a difference science project? Are you working on two separate projects?

It would help us help you if you could describe your science project. That way we can understand the context and background related to your question.
Huzaifaf
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Re: Which vein is nearest to the surface of skin?

Post by Huzaifaf »

Hello,
Yes, all my questions are relating to a single science project. Basically, I am working on an idea to prevent heat strokes. As you would know heat stroke occurs when the body temperature of a person exceeds past its limits, so, my idea is to perform an endothermic reaction between Sodium Bicarbonate and Acetic acid in a small container and then put that cold container on the vein which is nearest to the surface of skin. As veins carry blood and blood flows throughout the body so, the body temperature of the person should decrease. For this, I need to know that which vein is nearest to the surface of skin, I think that the veins on neck or on forehead are nearest but I am not sure.
Please tell what you think of my idea and also if you think it is practically possible and also, ofcourse, that which vein is nearest to the surface of skin.
Thank you.
Huzaifaf
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Re: Endothermic reaction

Post by Huzaifaf »

Hello,
Thanks for informing me, I will make sure that from now on I post all the questions which are related to the same science project together.
For the decription of my project, I am working on an idea to prevent heat strokes. As you would know heat stroke occurs when the body temperature of a person exceeds past its limits, so, my idea is to perform an endothermic reaction between Sodium Bicarbonate and Acetic acid in a small container and then put that cold container on the vein which is nearest to the surface of skin. As veins carry blood and blood flows throughout the body so, the body temperature of the person should decrease.
I read on a site that during a reaction between 1/2 tea spoon baking powder and 10 ml vinegar, the temperature of the container drops by approximately 7 C. If I increase the quantities of the reactants by 5 times, will the tempearture decreased will also become approximately 35 C ?
Please tell what you think of my idea and also if you think it is practically possible.
Thank you.
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Re: Endothermic reaction

Post by norman40 »

Hi Huzaifaf,

You’re on the right track. Increasing the amounts of acetic acid and sodium bicarbonate in your reaction should produce a larger temperature change.

The temperature change depends on the heat capacity of your solution and its container, and the amount of energy produced by the reaction. The amount of energy depends on the amounts of reactants (acetic acid and sodium bicarbonate) and reaction products formed (sodium acetate, carbon dioxide, water).

If you increase the amounts of reactants by a factor of five, you’d expect a fivefold increase in the temperature change if the heat capacity is constant and if the increased amounts of reactants yield amounts of reaction products that are increased in the same proportion.

In this case the heat capacity is pretty much determined by the amount of water in your solution. If you add water when you increase the reactant amounts, the heat capacity will increase and the temperature change will be less than the factor of five. As the temperature decreases, the reaction rate will be slower. This could result in reduced amounts of product formation, reduced energy and a temperature change that is less than a factor of five.

In your other post from yesterday, you asked about thermometer placement when measuring the temperature change from this reaction. My suggestion is to put the thermometer bulb in the solution. Allow some time for the temperature reading to stabilize. Then start the reaction and make temperature readings every 30 seconds until the readings stabilize again.

I hope this helps. Please ask again if you have more questions.

A. Norman
Huzaifaf
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Re: Endothermic reaction

Post by Huzaifaf »

Hello Norman,
You have already helped me a lot with the first part of the project and now I look forward to your help for the second part.
•If you have read my question which I posted in the Life, Earth and Social sciences forum, you would know that the main idea behind cooling the container was to then place the container on the nerve which is closest to the surface of skin. As nerves carry blood and blood flows throughout the body so this should ultimately lower the body temperature. For this, I would like your help to kindly tell me that which nerve do you think is closest to skin.
•I was also thinking that I should perform this experiment in a container whose three sides are made up of an insulator and one side of a conductor. Maybe, in this way less heat would enter the container and the side made of conductor would be placed on the nerve.
I would appreciate your help in this matter.

Huzaifa.
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Re: Endothermic reaction

Post by norman40 »

Hi Huzaifaf,

I have to say that anatomy is well outside my expertise. But I think that there are numerous blood vessels near the surface of the skin. When treating heat stroke I think that cooling large areas of skin is necessary. One way to do this is to apply cold compresses to areas of the body with relatively more blood vessels close to the skin. The following links contain more information about first aid for heat stroke.

http://www.webmd.com/a-to-z-guides/heat ... -treatment

http://m.wikihow.com/Treat-Heatstroke

The type of insulated container you described might limit the heat transfer and keep your reaction solution cold for a longer time that an uninsulated container. On the other hand, if you were using such a container as a cold compress for heat stroke first aid, the limited area for heat conduction might be a disadvantage. That is, you might want to maximize the heat conduction area in contact with the skin.

I hope this helps. Please ask again if you have more questions.

A. Norman
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Re: Endothermic reaction

Post by amyc »

Huzaifaf - please keep in mind that a project or exploration like this will require review by SRC.

All experimentation on humans requires review by SRC. Given the project you have outlined, we would also recommend that you run the experimental procedure by a medical doctor to get their input on 1) any potential safety issues for the participants, and 2) any ideas for improvements to the experiment above and beyond safety.

Information about the SRC review process: https://www.sciencebuddies.org/science- ... _src.shtml

If the SRC process seems daunting, you could avoid experimenting on people/animals and instead simulate the effects. We can offer some suggestions for how you could modify your plan to take this approach, if you want to consider that.

Amy
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Huzaifaf
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Re: Endothermic reaction

Post by Huzaifaf »

Hey Amy,
Maybe you are right but I don't see how this experiment can be dangerous for a human being as there will not be any direct contact with the chemicals being used or any other harmful thing.

Huzaifa
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Re: Endothermic reaction

Post by MadelineB »

Hello Huzaifaf,
I would like to second the expert advice that Amy gave to you. The guidelines that she mentioned apply to any experiments which involve human subjects. It will be up to the reviewers to evaluate the safety of your intended procedures. Keep in mind that they will evaluate the general safety of the procedures and the potential effects on your human subjects, not just the potential of your actual chemicals.

Let us know if you have any questions about the guidelines or help preparing your study for review.
Huzaifaf
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Re: Endothermic reaction

Post by Huzaifaf »

Hello!
I performed the experiment and following are the results:
--------------------------------------------------------------------------------------------------------------------------------------------------
AMOUNT OF ACETIC ACID (1M) : 50ml
AMOUNT OF Baking Soda ( Sodium Bicarbonate) : 2+1/2 (2.5) teaspoons approximately 12.27gm
Initial Temperature : 32°C
Final Temperature : 22°C
Difference in Temperature : -10°C
--------------------------------------------------------------------------------------------------------------------------------------------------
The weight of 2.5 teaspoons given above is as I weighed it but according to ( http://www.aqua-calc.com/calculate/volume-to-weight ) 2.5 teaspoons is equal to 27.5gm. Please tell me if I used the wrong amount of Sodium Bicarbonate.

Also, please tell me if there is a way I can find out that how many grams of Sodium Bicarbonate will completely react with 50 ml of 1M Acetic Acid i.e no Acetic Acid or Sodium Bicarbonate remains unused. Btw I used Baking Soda in place of Sodium Bicarbonate, I hope that it doesn't make a difference.

My target was to reduce the temperature to 0°C. If you could suggest me the changes that I should make in order to achieve my target I would be very much grateful. Kindly guide me whether I should use acetic acid of greater concentration, or should I increase the quantity of Sodium Bicarbonate or Acetic acid in order to achieve my target.

Your help in any of the above problems would be much appreciated.
Thank you.
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Re: Endothermic reaction

Post by norman40 »

Hi Huzaifaf,

One mole of acetic acid reacts with one mole of sodium bicarbonate to form carbon dioxide, water and sodium acetate. The following link shows the balanced chemical equation and some other details.

http://www.middleschoolchemistry.com/mu ... r6/lesson2

In your experiment you had 0.05 moles of acetic acid (50 mL X 1 M = 0.05 moles) in the starting solution. You added 0.146 moles of sodium bicarbonate (12.27 g/84 g/mole = 0.146 moles). So you had more than enough sodium bicarbonate to react with all of the acetic acid. If you wanted to have an equal molar amount of sodium bicarbonate, you’d need 4.2 g (84 g/mole X 0.05 moles). But an excess of one of the reactants is a good idea to ensure that all of the other reactant is used.

Take a look at the background section of the project described at the following link.

https://www.sciencebuddies.org/science- ... background

Equation 1 shows the relationship of temperature change (t), reaction energy change (q), heat capacity (c) and solution mass (m).

Using the data from your experiment we can calculate q for your reaction. The mass of the solution (m) you made was 62.27 g (50 mL acetic acid in water at a density of 1 g/mL plus the 12.27 g of sodium bicarbonate). We’ll assume that the heat capacity (c) of the solution is the same as for water (4.18 J/g/deg C). So q = (62.27 g)(4.18 J/g/deg C)(10 deg temperature change) or 2602.9 J.

According to equation 1, a larger temperature change requires a larger energy change (more than 2602.9 J) or a smaller solution mass (less than 62.27 g). Either way, you’d need a higher concentration of acetic acid in your solution. For example, if you used an acetic acid concentration of 3 M your 50 ml of solution would contain 0.15 moles of acetic acid. And you’d expect a reaction energy change of around 7800 J (a factor of 3 increase) if all of the acetic acid reacted. The expected temperature change should be close to 30 degrees.

I’m assuming that you used vinegar as you acetic acid source (the acetic acid concentration in vinegar is about 1 M). To make a 3 M acetic acid solution, you’ll need a more concentrated acid source. You may need to ask a teacher for help with sourcing acetic acid. Handling concentrated acids can be dangerous so you should get help from your teacher with preparing the acetic acid solution. Alternatively you might want to try the ammonium nitrate experiment described in the above link.

I hope this helps. Please ask again if you have more questions.

A. Norman
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