EK Chemistry 1001, Question 572

[sillyjoe]

The question reads:

Which of the following best describes the process by which carbon dioxide is dissolved in water?
A. Carbon dioxide changes phase from gas to liquid
B. Carbon dioxide changes phase from gas to aqueous
C. Water changes phase from liquid to aqueous
D. Carbon dioxide undergoes a chemical reaction with the water to form a new substance

B is correct. Read all the answer choices! When carbon dioxide is dissolved in water, it does not liquefy.

Is this question a bit contrived? Doesn't D also occur when CO2 dissolves in water?

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[pepocho]

.

 

[sillyjoe]

the key word is "dissolved", I believe (as always, I would like a second opinion) that dissolved entails that the reaction was a physical change. Since it is not a chemical change. It cannot be D.

EDIT: you know what, yeah I can see where you going from. carbonic acid. Ill chalk this one up as a bad question. I mean I guess you can say the emphasis is on "best", since carbonic acid only occurs in small amounts

True, but in general CO2 only dissolves in small amounts, but I guess you are right with best.

 

[orangetea]

This is the reaction.. I am pretty sure.

CO2(g) + H2O(l) <==> H2CO3(aq)

It's what happens in your carbonated beverages.. that's how I use it to remember. 😉

 

[sillyjoe]

This is the reaction.. I am pretty sure.

CO2(g) + H2O(l) <==> H2CO3(aq)

It's what happens in your carbonated beverages.. that's how I use it to remember. 😉

I agree, but the correct answer was B not D 🤔

 

[Czarcasm]

What a silly question because you could argue both B and D is correct. At the end of the day, CO2 dissolved in water will react with water to form carbonic acid which can dissociate into HCO3- and H+. You might argue that this process requires an enzyme, but enzymes make this otherwise spontaneous reaction occur quicker.

 

[sillyjoe]

What a silly question because you could argue both B and D is correct. At the end of the day, CO2 dissolved in water will react with water to form carbonic acid which can dissociate into HCO3- and H+. You might argue that this process requires an enzyme, but enzymes make this otherwise spontaneous reaction occur quicker.

Agreed, but in general I believe you can't really dissolve so much CO2 in water so it definitely does occur at levels high enough to show a pH change in seltzer water as opposed to pure water.

 

[orangetea]

Well the answer is D. because diet coke is made with pure honesty and integrity.

 

[sillyjoe]

Well the answer is D. because diet coke is made with pure honesty and integrity.

HAHAHA

I just looked it up and the pH of sparkling water is generally between 3 and 4 which to me makes D a correct enough answer to make this a crap question 😉

http://books.google.com/books?id=C0...=en#v=onepage&q="carbonated water" ph&f=false

 

[pepocho]

.

 

[sillyjoe]

all I know is CO2 exist as HCO3-, directly dissolved in water, or as a carbohemoglobin. and that's enough for me to know 😎

Ha, thankfully there is no hemoglobin in sparkling water! Only CO2 and carbonic acid/carbonate.

 

[IslandStyle808]

From what I remember, blood carries CO2 in the form of bicarb because CO2 can't dissolve that well. This is how the majority of CO2 is transported in the blood, but then again you have enzymes helping. Yeah I agree that is a bad question.