Chemistry pH problem help NaOH and HCl

In summary, the conversation discusses a chemistry problem involving calculating pH after adding different volumes of 0.32M HCl to 25 mL of 0.16M NaOH. The speaker is having trouble finding the correct answer for options b through f and asks for help. The solution involves determining the excess moles of NaOH or HCl and using the relationship 14 = pH + pOH.
  • #1
marcuss
12
0
Chemistry pH problem help please NaOH and HCl

Calculate the pH after the following total volumes of .32M HCl have been added to 25 mL of 0.16M NaOH
a. 0 mL c. 12.4 mL e. 12.6 mL
b. 1 mL d. 12.5 mL f. 15.0 mL



A. i have answered correctly but i can't seem to get the right answer for any of the others i tried putting them in mmol but it never seems to work if someone could just tell me how to do b through f i would be very pleased thank you.
 
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  • #2


The exercise is a neutralization reaction. Determine which moles of NaOH or HCl is in excess. That would be the one which affects the pH. A relationship which is helpful is 14 = pH + pOH
 
  • #3


Hello,

Thank you for reaching out for help with this chemistry pH problem. It seems like you have successfully calculated the pH for the first scenario where 0 mL of HCl is added. To calculate the pH for the other scenarios, you will need to use the Henderson-Hasselbalch equation.

The Henderson-Hasselbalch equation is pH = pKa + log([base]/[acid]), where pKa is the negative logarithm of the acid dissociation constant, [base] is the concentration of the base (in this case NaOH), and [acid] is the concentration of the acid (in this case HCl).

To solve for the pH in these scenarios, you will first need to calculate the concentration of HCl after the given volume has been added. To do this, you can use the dilution formula: M1V1 = M2V2, where M1 and V1 are the initial concentration and volume of HCl, and M2 and V2 are the final concentration and volume after the addition of HCl.

Once you have calculated the concentration of HCl, you can plug it into the Henderson-Hasselbalch equation along with the concentration of NaOH (0.16M) to solve for the pH. Remember to convert the volumes to liters before using the equation.

I hope this helps you to successfully calculate the pH for scenarios b through f. If you are still having trouble, please provide your calculations and I will be happy to review them and offer further assistance.

Best of luck with your problem-solving!
 

Related to Chemistry pH problem help NaOH and HCl

1. What is the purpose of using NaOH and HCl in a chemistry pH problem?

NaOH (sodium hydroxide) and HCl (hydrochloric acid) are commonly used in chemistry pH problems because they are strong bases and acids, respectively. This means they have a high concentration of hydrogen ions (H+) and hydroxide ions (OH-), which are essential in determining the pH of a solution.

2. How do you calculate the pH of a solution using NaOH and HCl?

To calculate the pH of a solution containing NaOH and HCl, you will need to know the concentration of each substance and their respective dissociation constants. Then, you can use the Henderson-Hasselbalch equation: pH = pKa + log([A-]/[HA]), where pKa is the negative logarithm of the acid dissociation constant and [A-] and [HA] represent the concentrations of the conjugate base and acid, respectively.

3. What is the difference between a strong acid/base and a weak acid/base?

A strong acid/base is one that fully dissociates in water, meaning all of its molecules break apart into ions. In contrast, a weak acid/base only partially dissociates, resulting in a lower concentration of ions in solution. Strong acids and bases have higher dissociation constants, making them more powerful in terms of pH changes.

4. Can you use other acids and bases besides NaOH and HCl in a pH problem?

Yes, there are many other acids and bases that can be used in pH problems, such as sulfuric acid, acetic acid, and ammonia. The choice of acid or base depends on the specific problem being solved and the desired pH range.

5. How does temperature affect the pH of a solution containing NaOH and HCl?

Temperature can have a significant impact on the pH of a solution containing NaOH and HCl. As temperature increases, the dissociation of both substances also increases, leading to a higher concentration of H+ and OH- ions and a lower pH. This effect is more pronounced in weak acids and bases compared to strong ones.

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