Abstract
This experiment aims to determine the value of X in the given sample of \( (COOH)_2 \cdot XH_2O \) dissolved per dm3 using volumetric analysis.
Introduction
The compound \( (COOH)_2 \cdot XH_2O \), also known as oxalic acid dihydrate, is a commonly used primary standard substance in volumetric analysis. By titrating a solution of known concentration of sodium hydroxide (NaOH) against the oxalic acid solution, the value of X can be determined.
Experimental Details
Procedure:
- Weigh 6.3g of \( (COOH)_2 \cdot XH_2O \) sample accurately using a digital balance.
- Dissolve the sample in distilled water in a 100ml volumetric flask.
- Dilute the solution to the mark with distilled water and mix thoroughly to ensure homogeneity.
- Fill a burette with standardized sodium hydroxide (NaOH) solution of known concentration.
- Add a few drops of phenolphthalein indicator to the oxalic acid solution.
- Titrate the oxalic acid solution with NaOH solution until a faint pink color persists.
- Record the initial and final burette readings to calculate the volume of NaOH solution used.
Observations and Calculations:
Let's assume that the volume of NaOH solution used in titration is V ml and its concentration is C M.
The balanced chemical equation for the reaction between oxalic acid and sodium hydroxide is:
\[ 2NaOH + (COOH)_2 \cdot XH_2O \rightarrow Na_2(COO)_2 + 2H_2O \]
From the equation, it is clear that 2 moles of NaOH react with 1 mole of oxalic acid dihydrate.
Hence, the molarity of the oxalic acid solution is:
\[ Molarity\ of\ oxalic\ acid\ solution\ (M_1) = \frac{{2 \times C \times V}}{{1000}}\]
Given that 6.3g of \( (COOH)_2 \cdot XH_2O \) is dissolved per dm3, we can calculate the molarity of the oxalic acid solution (M2):
\[ M_2 = \frac{{6.3}}{{(90 + 2 \times 16) \times (X + 2 \times 1) \times 1000}}\]
Equating \( M_1 \) and \( M_2 \), we can solve for X.
Conclusion
The value of X in the given sample of \( (COOH)_2 \cdot XH_2O \) dissolved per dm3 is determined to be [calculated value of X].
Precautions
- Ensure accurate weighing of the sample.
- Use standardized solutions and calibrated glassware.
- Handle chemicals with care to prevent accidents.
- Perform titration carefully to avoid overshooting the endpoint.
- Use suitable indicators and record observations accurately.
Short Questions
-
What is the compound \( (COOH)_2 \cdot XH_2O \) commonly known as?
Answer: Oxalic acid dihydrate -
What is the primary objective of using volumetric analysis in this experiment?
Answer: To determine the value of X in the given sample. -
How is the volume of sodium hydroxide (NaOH) solution used in titration measured?
Answer: By recording the initial and final burette readings. -
What is the role of phenolphthalein indicator in the titration process?
Answer: To indicate the endpoint of the titration. -
Why is it important to standardize the sodium hydroxide (NaOH) solution before titration?
Answer: To determine its exact concentration accurately. -
What is the significance of accurately weighing the sample in this experiment?
Answer: To ensure precise calculations and reliable results. -
What is the formula to calculate the molarity of a solution?
Answer: Molarity (\( M \)) = \(\frac{{\text{{Number of moles}}}}{{\text{{Volume in liters}}}}\). -
How is the endpoint of the titration determined?
Answer: When a color change occurs, indicating the completion of the reaction. -
What precaution should be taken while handling chemicals in the laboratory?
Answer: Wear appropriate protective gear and handle with care to avoid accidents. -
What is the role of distilled water in preparing solutions?
Answer: To dissolve the solute and ensure uniformity of the solution. -
What is the purpose of diluting the oxalic acid solution to the mark in the volumetric flask?
Answer: To achieve the desired volume and concentration of the solution. -
Why is it important to mix the solution thoroughly after dilution?
Answer: To ensure homogeneity of the solution. -
What is the chemical formula of sodium hydroxide?
Answer: NaOH. -
What precaution should be taken to prevent contamination of solutions during the experiment?
Answer: Use clean glassware and avoid cross-contamination. -
What is the role of the burette in titration?
Answer: To deliver precise volumes of the titrant solution. -
How is the volume of titrant solution measured during titration?
Answer: By reading the burette scale and recording the initial and final readings. -
What is the purpose of using a primary standard substance in the standardization process?
Answer: To ensure accuracy and reliability of the titration results. -
What precaution should be taken while performing titration to avoid errors?
Answer: Perform the titration slowly and cautiously to avoid overshooting the endpoint. -
What is the role of sulfuric acid in the titration?
Answer: To acidify the solution and provide suitable conditions for the reaction. -
How is the concentration of the standardized solution determined after titration?
Answer: By calculating the volume and concentration of the titrant used.
Multiple Choice Questions (MCQs)
-
Which compound is commonly used in volumetric analysis for determining the value of X?
- a) NaCl
- b) HCl
- c) \( (COOH)_2 \cdot XH_2O \)
- d) NaOH
-
What is the role of phenolphthalein indicator in the titration process?
- a) To provide color to the solution
- b) To neutralize the oxalic acid
- c) To indicate the endpoint of the titration
- d) To increase the solubility of oxalic acid
-
What is the balanced chemical equation for the reaction between oxalic acid and sodium hydroxide?
- a) \( NaOH + H_2(COOH)_2 \rightarrow Na(COOH)_2 + 2H_2O \)
- b) \( 2NaOH + (COOH)_2 \cdot XH_2O \rightarrow Na_2(COO)_2 + 2H_2O \)
- c) \( NaOH + H_2SO_4 \rightarrow Na_2SO_4 + 2H_2O \)
- d) \( 2NaOH + H_2O_2 \rightarrow 2NaOH + 2H_2O \)
-
What is the purpose of standardizing the NaOH solution before titration?
- a) To provide accurate measurements
- b) To adjust the pH of the solution
- c) To increase the solubility of oxalic acid
- d) To determine the exact concentration of NaOH
-
What is the significance of recording initial and final burette readings during titration?
- a) To calculate the volume of oxalic acid solution used
- b) To measure the volume of NaOH solution used
- c) To determine the color change of the solution
- d) To calculate the volume of KMnO4 solution used