Solar Water Heater

[tatsunaku]

Objectives:
Heat 2 fluid ounces of any kind of liquid in a small amount of time.

I need help! And I don't think this is going to work since autumn is coming up, limiting the sunlight. And i can't change. I have an idea. Buy some solar powered warmers and wrap it around the cup holding the liquid.

I probably use enthanol since its heat capacity is lower than water. I think that it will heat up faster.

[deleted-2131]

First of all, what temperature do you need to heat the liquid to? How much time do you have to heat the liquid? What is the starting temperature of the liquid?

Your basic ideas are very good, and I think that if you answer the above questions we can come up with more good ideas!

As to the liquid of choice, I would reccomend using the liqiud with the lowest heat capacity that is available to you, but you will also need to watch the vapor pressure of the liquid (e.g. you don't want all your liquid to evaporate before the lab is over.)


Sounds like an interesting project. I think that you are on the right track. Let's see if together we can come up with an amazing project!

[tatsunaku]

I wasn't given an amount of time. I'll have to check that with my teacher.

And about the temperature...that will be depended on the time...i think

As for the vapor pressure, if it evaporates too quickly, I'll add some salt or sugar to increase the boiling point...so that will reduce the evaporation...I think

[tatsunaku]

oh yeah...one more thing...I think that I'm going to use a flat cup cause then it'll cover more surface area of the water so then it will heat up more even and possibly faster

[deleted-2574]

Hi tatsunaku!

Based on previous posts, it looks you're on the right path!

An additional thought:

If you submit “what is the heat capacity of a liquid?� to answers.com, you get the definition of heat capacity and a series of web pages that includes:

http://www.chm.davidson.edu/ChemistryAp ... hanol.html (which has ethanol experiments).

N. B.: As for sugar and use of flat cups, sounds like they could be experimental variables and be tested. It’s best to test rather than make assumptions.

Two notes about using answers.com (and any other search engine):

1. Subtle wording changes can produce different results.

2. "Sponsored Links" are commercials. It's best to use “Answers from the Web� (currently in beta) or “Web Search."

[deleted-2131]

Using a flat cup is a great idea! The more surface you have exposed, the better.

Vapor pressure isn't really related to boiling point. See http://www.answers.com/topic/vapor-pressure. The issue is that something with a low vapor pressure (e.g. acetone) may completely vaporize is put in a container that has just regular air in it, not because it is boiling, but because it is trying to reach an equilibrium. (If this is way over your head, just ignore it and stick to ethanol.)

As you get more details, let me know and we can work out how exactly you are going to make the heater. The material that you make the heater out of and its color will have a large effect on its ability to heat the liquid.

[deleted-71447]

Hi Tatsunaku,
That is a clever idea to use a liquid with a low specific heat capacity. I just wanted to add one small suggestion to the expert advice already offered here. Instead of ethanol, which is quite flammable, volatile, and mildly toxic, you could also use a vegetable oil:
http://www.engineeringtoolbox.com/speci ... d_151.html

Regards,
Chris

[tatsunaku]

Opps...my mistake...the vapor pressure depends on how volatile the liquid is...i think