Determine amount of base to use for titration?

In summary: How many moles of NaOH will react with 325 mg of ASA?In summary, the student is trying to determine the concentration of a secondary standard solution of NaOH that will be used to titrate with 325 mg of acetylsalicylic acid dissolved in 10 mL of ethanol. They have tried using 0.1 mol/L of NaOH but their teacher suggested working backwards from the chemical equation to find the optimal concentration. The student will need to understand the stoichiometry of the reaction to determine how many moles of NaOH will react with the ASA.
  • #1
NamikazeBurst
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Homework Statement


How to find concentration of NaOH to titrate ASA with 30-40 mL

I am doing a lab in which I need to use a base with a known concentration (a standard solution that I have to dilute to make a secondary standard) to react with an acid with an unknown concentration. I then have to find the mass of the acid.

I am wondering how I am supposed to find what concentration my secondary standard is supposed to be. I need to use 30-40 mL of it per tablet of ASA (the acid we are using), which are 325 mg each. I guessed 0.1 mol/liter, which can be used, but doesn't follow under 30-40 mL. How do I determine the concentration of secondary standard that will give me 30-40 mL of NaOH (the base) which will dilute 325 mg of ASA dissolved in 10 mL of ethanol?

Summary:
- I have to make a standard solution and dilute to make a secondary standard
- I must use NaOH (starting as a solid) as the base
- I must use 325mg of acetylsalicylic acid as the acid with the unknown concentration
- For best results, I should use 30-40 mL of the secondary standard to perform the titration
- The ASA is dissolved in 10 mL of ethanol
- I am trying to figure out the concentration of the secondary standard of NaOH that will titrate with 30-40 mL

I tried using 0.1 mol/L of NaOH as it seemed dilute enough but not too dilute. I got values of 4g of initial NaOH. My teacher said to work backwards from the equation (ASA + NaOH -> H20 + NaASA-H) [If this is correct, I didn't type the actual chemical equation], but I do not know how that will help. He has not taught us how to calculate equivalence points.

Homework Equations


C = n/v
n = m/M
CiVi = CfVf

The Attempt at a Solution


4g of NaOH diluted to 250 mL after making a primary standard
0.1 mol/liter --> teacher says it will work but is not optimal
 
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  • #2
Do as your teacher said. You don't need to calculate equivalence points for that, just follow the stoichiometry.

For that you will need to understand what is the reaction taking place. How does the acetylsalicylic acid react with NaOH?
 

FAQ: Determine amount of base to use for titration?

1. How do I calculate the amount of base needed for titration?

The amount of base needed for titration can be calculated using the formula: moles of acid (or analyte) x molar ratio x molar mass of base = amount of base needed. This formula takes into account the molar ratio between the acid and base, as well as the molar mass of the base.

2. What is the molar ratio between the acid and base in a titration?

The molar ratio between the acid and base in a titration can be determined by looking at the balanced chemical equation. The coefficient of the acid and base in the equation represents the molar ratio. For example, if the balanced equation is HCl + NaOH → NaCl + H2O, the molar ratio between HCl and NaOH is 1:1.

3. How does the concentration of the acid affect the amount of base used in titration?

The concentration of the acid directly affects the amount of base needed for titration. The higher the concentration of the acid, the more base will be needed to neutralize it. This is because a higher concentration of acid means there are more moles of acid present, and more moles of acid require more moles of base for neutralization.

4. Why is it important to use the correct amount of base in titration?

Using the correct amount of base in titration is crucial for obtaining accurate and reliable results. If too much base is added, the endpoint of the titration will be overshot, resulting in a higher volume of base used and a falsely high concentration of the acid being determined. Similarly, if too little base is added, the endpoint will be undershot and the concentration of the acid will be falsely low.

5. Can I use any type of base for titration?

No, not all bases are suitable for titration. It is important to use a strong base with a known concentration for accurate results. Commonly used bases for titration include sodium hydroxide (NaOH), potassium hydroxide (KOH), and ammonium hydroxide (NH4OH). It is also important to ensure that the base does not react with the acid being titrated, as this would affect the accuracy of the results.

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