Chemistry Practice Questions: pH Mixture and Gas Production

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In summary, the pH of a mixture of 50ml or 0.4 M HCl and 50ml 0.4 Ba(OH)2 is closest to 12.6. The volume of CO2 gas at 25*C and 101.3kPa is produced by the complete combustion of 4.0g of carbon in oxygen.
  • #1
Omm
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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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  • #2
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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  • #3
Thanks a heap! I will take a look at the video/s and see if I can get it :)
 
  • #4
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?
 
Last edited:
  • #5
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?
 
  • #6
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.
 

Related to Chemistry Practice Questions: pH Mixture and Gas Production

1. What are the basic principles of chemistry?

The basic principles of chemistry include the study of matter and its properties, how substances interact and form new substances, and the laws and theories that govern these interactions.

2. What is the difference between an element and a compound?

An element is a pure substance made up of only one type of atom, while a compound is a substance made up of two or more different types of atoms bonded together.

3. How do you balance a chemical equation?

To balance a chemical equation, you must ensure that the number of atoms of each element on both sides of the equation are equal. This is achieved by adjusting the coefficients of the reactants and products.

4. What is the difference between an acid and a base?

An acid is a substance that donates a proton (H+) in a chemical reaction, while a base is a substance that accepts a proton. Acids tend to have a sour taste and can corrode metals, while bases have a bitter taste and can feel slippery.

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