Chemistry Practice Questions: pH Mixture and Gas Production

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The discussion centers on solving two chemistry practice questions related to pH and gas production. For the first question regarding the pH of a mixture of HCl and Ba(OH)2, the consensus is that the pH is closest to 12.6, as Ba(OH)2 is a stronger base that dominates the solution's pH. The second question involves calculating the volume of CO2 produced from the combustion of carbon, with the answer determined to be 12.7L. Participants suggest using resources like Khan Academy for better understanding of acid-base calculations. The student expresses gratitude after finding the answers and understanding the concepts.
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I am only a high school student so take some pity, I have an exam tomorrow and am trying to teach myself the method. But alas, not working >.<

Could someone please answer them for me with working? My teacher kind of rushed over this and I didnt really understand:

Q1) The pH of a mixture of 50ml or 0.4 M HCl and 50ml 0.4 Ba(OH)2 is closest to:

12.6
7.0
14.0
1.0

Q2) What volume of CO2 gas at 25*C and 101.3kPa is produced by the complete combustion of 4.0g of carbon in oxygen?

25.4L
12.7L
8.47L
4.24L

Please show working + formulas

Thanks a heap!
 
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Khan Academy has a really great series of videos about calculating weak/strong acid/bases. I recommend you check out that series of videos located here:
http://www.khanacademy.org/video/introduction-to-ph--poh--and-pkw?playlist=Chemistry

It's only about 30 minutes long and he does a great job explaining exactly how to solve these questions.

If you prefer, if you write out what you have worked the questions to so far, I will help you get to the desired result.
 
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Thanks a heap! I will take a look at the video/s and see if I can get it :)
 
Yer, still having trouble. Could you please work the answer so I can see the process for 1?

EDIT: Ok I don't think there is like a formula or equation to follow for it? So it is just knowing that they both fully disassociate but Ba(OH)2 occupies more therefore it is basic. A pH of 14 in unreasonable with the HCl in the solution so by elimination it is 12.6?
 
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Omm said:
I am only a high school student so take some pity, I have an exam tomorrow and am trying to teach myself the method. But alas, not working >.<

Could someone please answer them for me with working? My teacher kind of rushed over this and I didnt really understand:

Q1) The pH of a mixture of 50ml or 0.4 M HCl and 50ml 0.4 Ba(OH)2 is closest to:

12.6
7.0
14.0
1.0

What happens when these two are mixed? acid + base -> ?

Omm said:
Q2) What volume of CO2 gas at 25*C and 101.3kPa is produced by the complete combustion of 4.0g of carbon in oxygen?

25.4L
12.7L
8.47L
4.24L

Please show working + formulas

Thanks a heap!

How many moles of CO2 is formed by the combustion?
 
Answer to A is 12.6. Acid + Base --> Salt + Water however there is one H in HCL but two OH in Ba(OH)2 This will shift the pH to more basic.

I got it now as well as the CO2 produced. Thanks anyways.
 
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