Q1. What happens to these acids in water? Model this with your paperclip
molecules. How does a weak acid and a strong acid differ? Take a picture
of your model and insert here. (Hint: Think about how a strong acid
dissociates differently than a weak acid). (2 points)
ACETIC ACID
HYDROCHLORIC ACID
(I only had four paper clips, sorry) When a weak acid is added to water, equilibrium will form where
aqueous acid molecules (HA) react with water to form aqueous hydronium ions and anions (A-). A strong
acid will dissociate completely in solution unlike weak acids.
Q2. If the acidity of a solution is based on the number of H + ions (more
ions = more acidic), which of your two solutions would be more acidic?
Explain. (1 point)
HCl is more acidic than acetic acid because when put into water it will dissociate completely unlike acetic
acid that only partly dissociates.
Q3. Now let’s compare solutions. Imagine that I put 10 “weak” acid
molecules into a new glass of water. How many H+ ions will you have in
each of these solutions? (1 point)
1 CHEM-126
This study source was downloaded by 100000860007226 from CourseHero.com on 02-06-2023 05:50:29 GMT -06:00
https://www.coursehero.com/file/64016122/chem-lab-3docx/
, 5 strong acid molecules: ___5___ H+ ions 10 weak acid molecules: ___2___ H+ ions
Q4. Which will be more acidic, the solution with 5 strong acids, or the one
with 10 weak acids?
Circle one. Why did you choose that solution? (1 point)
5 strong acid molecules OR 10 weak acid molecules
5 strong acid molecules will be more acidic because there are more H+ ions.
Q5. What if I add 50 weak acid molecules to water? How many H + ions will
each solution have? (1 point)
5 strong acid molecules: ___5____ H+ ions 50 weak acid molecules: ___10____ H +ions
Q6. Which solution will be more acidic? Why? (1 point)
5 strong acid molecules OR 50 weak acid molecules
50 weak acid molecules will be stronger and more acidic because it has double the amount of ions in
solution.
Part 2 – Determining the pH of Household Substances
Strong acids and bases are dangerous, and can really only be found in laboratories or chemical
plants. Weak acids and bases, however, are incredibly useful, and can be found all around us!
But how do you test whether something is acidic or basic?
You can rank how acidic or basic something is using a scale called the “pH scale.” As we
learned in the last section, the number of hydrogen (H +) or hydroxyl (OH-) ions in a solution
affects how acidic or basic it is. pH is measured using chemicals that change color when they
bind to the extra hydrogen or hydroxyl ions in water. So, for example, the more acidic a solution,
the more hydrogen ions there are, and the more the color will change! A solution of water, where
the H+ and OH- ions are in balance, is called neutral, and it has a pH of 7. As you add more acid
(and therefore more hydrogen ions), the pH goes down. A pH of 0 is the strongest an acid can be
in water.
Alternatively, the more of a base you put in water, the more hydroxyl ions there are (either from
the base itself, or from the broken water molecules). This means that there are less H + ions than
there would be in a neutral (water) solution, and so you will have a pH higher than 7. As you get
farther from neutral, the solution gets more basic (and the number of OH - molecules increases).
A pH of 14 is the strongest a base can be in water.
Let’s measure the pH of some things that you can find in your house.
2 CHEM-126
This study source was downloaded by 100000860007226 from CourseHero.com on 02-06-2023 05:50:29 GMT -06:00
https://www.coursehero.com/file/64016122/chem-lab-3docx/
molecules. How does a weak acid and a strong acid differ? Take a picture
of your model and insert here. (Hint: Think about how a strong acid
dissociates differently than a weak acid). (2 points)
ACETIC ACID
HYDROCHLORIC ACID
(I only had four paper clips, sorry) When a weak acid is added to water, equilibrium will form where
aqueous acid molecules (HA) react with water to form aqueous hydronium ions and anions (A-). A strong
acid will dissociate completely in solution unlike weak acids.
Q2. If the acidity of a solution is based on the number of H + ions (more
ions = more acidic), which of your two solutions would be more acidic?
Explain. (1 point)
HCl is more acidic than acetic acid because when put into water it will dissociate completely unlike acetic
acid that only partly dissociates.
Q3. Now let’s compare solutions. Imagine that I put 10 “weak” acid
molecules into a new glass of water. How many H+ ions will you have in
each of these solutions? (1 point)
1 CHEM-126
This study source was downloaded by 100000860007226 from CourseHero.com on 02-06-2023 05:50:29 GMT -06:00
https://www.coursehero.com/file/64016122/chem-lab-3docx/
, 5 strong acid molecules: ___5___ H+ ions 10 weak acid molecules: ___2___ H+ ions
Q4. Which will be more acidic, the solution with 5 strong acids, or the one
with 10 weak acids?
Circle one. Why did you choose that solution? (1 point)
5 strong acid molecules OR 10 weak acid molecules
5 strong acid molecules will be more acidic because there are more H+ ions.
Q5. What if I add 50 weak acid molecules to water? How many H + ions will
each solution have? (1 point)
5 strong acid molecules: ___5____ H+ ions 50 weak acid molecules: ___10____ H +ions
Q6. Which solution will be more acidic? Why? (1 point)
5 strong acid molecules OR 50 weak acid molecules
50 weak acid molecules will be stronger and more acidic because it has double the amount of ions in
solution.
Part 2 – Determining the pH of Household Substances
Strong acids and bases are dangerous, and can really only be found in laboratories or chemical
plants. Weak acids and bases, however, are incredibly useful, and can be found all around us!
But how do you test whether something is acidic or basic?
You can rank how acidic or basic something is using a scale called the “pH scale.” As we
learned in the last section, the number of hydrogen (H +) or hydroxyl (OH-) ions in a solution
affects how acidic or basic it is. pH is measured using chemicals that change color when they
bind to the extra hydrogen or hydroxyl ions in water. So, for example, the more acidic a solution,
the more hydrogen ions there are, and the more the color will change! A solution of water, where
the H+ and OH- ions are in balance, is called neutral, and it has a pH of 7. As you add more acid
(and therefore more hydrogen ions), the pH goes down. A pH of 0 is the strongest an acid can be
in water.
Alternatively, the more of a base you put in water, the more hydroxyl ions there are (either from
the base itself, or from the broken water molecules). This means that there are less H + ions than
there would be in a neutral (water) solution, and so you will have a pH higher than 7. As you get
farther from neutral, the solution gets more basic (and the number of OH - molecules increases).
A pH of 14 is the strongest a base can be in water.
Let’s measure the pH of some things that you can find in your house.
2 CHEM-126
This study source was downloaded by 100000860007226 from CourseHero.com on 02-06-2023 05:50:29 GMT -06:00
https://www.coursehero.com/file/64016122/chem-lab-3docx/
