gwiyomi17 Posted May 25, 2013 Share Posted May 25, 2013 What are the evidences that a gas is dissolved in water??? Link to comment Share on other sites More sharing options...
ewmon Posted May 25, 2013 Share Posted May 25, 2013 What kind of water and gases? (Asking about the water might seem weird, but impure water may contain substances that interfere with the tests. For example, water out of the faucet may contain chlorine, fluorine, etc.) Link to comment Share on other sites More sharing options...
daniton Posted May 25, 2013 Share Posted May 25, 2013 What are the evidences that a gas is dissolved in water??? what do you mean by that? clarify it!! Link to comment Share on other sites More sharing options...
John Cuthber Posted May 25, 2013 Share Posted May 25, 2013 Ask a fish. Link to comment Share on other sites More sharing options...
gwiyomi17 Posted May 25, 2013 Author Share Posted May 25, 2013 what do you mean by that? clarify it!! What kind of water and gases? (Asking about the water might seem weird, but impure water may contain substances that interfere with the tests. For example, water out of the faucet may contain chlorine, fluorine, etc.) What assumption must we make about the dissolving of a gas (like N2(g), O2(g), CO2(g), NH3(g)) in PURE water for the solubility evidence to be valid? Bubbles are formed in a liquid solution. I need to come up with two or three more. Ask a fish. I will, if the fish is smarter than you are. 2 Link to comment Share on other sites More sharing options...
studiot Posted May 25, 2013 Share Posted May 25, 2013 Chemistry is a practical subject. Do you know some practical tests you can subject the water to? For instance what happens to litmus paper in pure water and water containing dissolved carbon dioxide, sulphur dioxide or nitrogen dioxide? What happens if you take a clear bottle of a fizzy drink and open the top? I am not sure what you mean by "bubbles are formed in a liquid solution"? Under what conditions? Bubbles will form if you boil that liquid, but they are not indications of dissolved gas. But they could be under other circumstances. Does this help? Link to comment Share on other sites More sharing options...
gwiyomi17 Posted May 25, 2013 Author Share Posted May 25, 2013 (edited) Chemistry is a practical subject. Do you know some practical tests you can subject the water to? For instance what happens to litmus paper in pure water and water containing dissolved carbon dioxide, sulphur dioxide or nitrogen dioxide? What happens if you take a clear bottle of a fizzy drink and open the top? I am not sure what you mean by "bubbles are formed in a liquid solution"? Under what conditions? *Bubbles will form if you boil that liquid, but they are not indications of dissolved gas. But they could be under other circumstances. Does this help? yes, I think so.. My teacher just gave us the lab paper, and all the data were already there. We did not conduct the experiment.This question bothers me. I already read my book but I don't think its related to the topic. How can I answer this if the questions are so confusing? I don't know what is it really asking. *I am thinking about my teacher's examples like the soda pop, carbon dioxide is dissolved. The bubbles and the fizzing of the opened can indicates that the carbon dioxide is dissolved. NOT sure about this. Edited May 25, 2013 by gwiyomi17 Link to comment Share on other sites More sharing options...
studiot Posted May 25, 2013 Share Posted May 25, 2013 *I am thinking about my teacher's examples like the soda pop, carbon dioxide is dissolved. The bubbles and the fizzing of the opened can indicates that the carbon dioxide is dissolved. NOT sure about this. Yeah, that's good. You need a clear bottle of the stuff to see what it is like before you open the lid. That is why a can will not do. Before you open it are there any / many bubbles? After you open it there is clear visible evidence of gas being released. You do not know that this gas is carbon dioxide, from this evidence. Further tests would be needed to establish that. Link to comment Share on other sites More sharing options...
gwiyomi17 Posted May 25, 2013 Author Share Posted May 25, 2013 Yeah, that's good. You need a clear bottle of the stuff to see what it is like before you open the lid. That is why a can will not do. Before you open it are there any / many bubbles? Yes, I think so.... but how does it indicate that a gas dissolve in the solution? Link to comment Share on other sites More sharing options...
studiot Posted May 25, 2013 Share Posted May 25, 2013 Well before you open it, you can see that there is a (nearly) clear liquid almost filling the bottle. This liquid is still, that is it is not fizzing or showing significant activity or evidence of gas, if you do not shake it. When you release the lid the fizzing starts. You can clearly see bubbles of gas in the liquid. Where did they come from if they were not dissolved? The obvious (and correct) conclusion is that they were dissolved. Link to comment Share on other sites More sharing options...
daniton Posted May 25, 2013 Share Posted May 25, 2013 I still didn't get what you really want to know but as far as I understand I think you want to know if there any thing to say whether a gas is dissolved or not. what your teacher say about the bubble is that the co2 was there in the solution,the reason you see the bubble is the co2 skipping out from the solution due to pressure decrease as you move the bottle which increase the volume. when I get to the question you could check the PH may be color change or some other staff. did I get you point? Link to comment Share on other sites More sharing options...
pwagen Posted May 25, 2013 Share Posted May 25, 2013 you could check the PH may be color change or some other staff.So bubbles, PH and... tasting it? Link to comment Share on other sites More sharing options...
daniton Posted May 25, 2013 Share Posted May 25, 2013 (edited) what???? Edited May 25, 2013 by daniton Link to comment Share on other sites More sharing options...
pwagen Posted May 25, 2013 Share Posted May 25, 2013 3 ways to decide whether there's a gas in a solution, OP's question! Mind you, I'm no chemist. Link to comment Share on other sites More sharing options...
studiot Posted May 25, 2013 Share Posted May 25, 2013 How does taste distinguish between dissolved gas and dissolved solid or dissolved other liquid? Link to comment Share on other sites More sharing options...
pwagen Posted May 25, 2013 Share Posted May 25, 2013 How does taste distinguish between dissolved gas and dissolved solid or dissolved other liquid?That's not how I read the question. As far as I understood it, the question is only whether gas has been solved, or it's pure water. Of course, if there are other options than gas, tasting probably wouldn't be definite, unless you're very familiar with the taste of a certain gas. Link to comment Share on other sites More sharing options...
studiot Posted May 25, 2013 Share Posted May 25, 2013 Taste is a possibility, but not conclusive. However, gwiyomi knows from a previous question that the solubility of gas decreases with temperature increase so if you heat water containg a dissolved gas, some will be evolved (that's a nice chemistry word) and may be collected and identified. 1 Link to comment Share on other sites More sharing options...
gwiyomi17 Posted May 25, 2013 Author Share Posted May 25, 2013 hmm..... What should I write then? Is it the observations that can be seen which indicates wether a gas is dissolved or the the explanation why it is dissolved in pure water?? Or proof that will make this observations and explanations true???? I'm really mess up with this lab,, Link to comment Share on other sites More sharing options...
Amaton Posted May 25, 2013 Share Posted May 25, 2013 hmm..... What should I write then? Is it the observations that can be seen which indicates wether a gas is dissolved or the the explanation why it is dissolved in pure water?? Or proof that will make this observations and explanations true???? I'm really mess up with this lab,, Generally, the solubility of a gas in water decreases as temperature increases (assuming other conditions held constant). Assuming a constant temperature, solubility in water typically increases as pressure increases. So if you have a saturated solution of gas in water, an increase in container pressure will cause the solution to become supersaturated. Thus, the vapor pressure of the solution will increase and could be read by some device within the container. I'm not an expert, so is this valid reasoning? Link to comment Share on other sites More sharing options...
gwiyomi17 Posted May 25, 2013 Author Share Posted May 25, 2013 (edited) Generally, the solubility of a gas in water decreases as temperature increases (assuming other conditions held constant). Assuming a constant temperature, solubility in water typically increases as pressure increases. So if you have a saturated solution of gas in water, an increase in container pressure will cause the solution to become supersaturated. Thus, the vapor pressure of the solution will increase and could be read by some device within the container. I'm not an expert, so is this valid reasoning? Yes, I think so... you guys really helped me a lot today. maybe i'll just gather more information so that I can improve it. Thanks! Edited May 25, 2013 by gwiyomi17 Link to comment Share on other sites More sharing options...
John Cuthber Posted May 26, 2013 Share Posted May 26, 2013 I will, if the fish is smarter than you are. If you can find a fish that's smarter than yourself, ask it where it gets its oxygen from. Link to comment Share on other sites More sharing options...
gwiyomi17 Posted May 29, 2013 Author Share Posted May 29, 2013 If you can find a fish that's smarter than yourself, ask it where it gets its oxygen from. well if I can, I will. If the fish will respond. I got your point though. sorry for being mean. peace Link to comment Share on other sites More sharing options...
studiot Posted May 30, 2013 Share Posted May 30, 2013 Strictly speaking I don't see that the observable fact of living fish demonstrates there is or is not gas dissolved in water. You need other evidence or knowledge, from biology, to make that deduction. You can, of course, design a series of experiments to prove that fish need oxygen and will die when the dissolved supply is exhausted. Incidentally there is a quantity in environmental science called the 'biological oxygen demand' (BOD) which is used in conjunction with a dissolved oxygen meter to measure water quality. Link to comment Share on other sites More sharing options...
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