Quantitative analysis of soda ash by double indicator
*why there is a need to boil distilled water in the preparation of base solutions?
*why a mixture of NaOH and NaHCO3 is incompatible?
*why there is a need t o boil the solution before reaching the methyl orange endpoint?
*is it possible to used NaOH as primary standard for HCl and the properties of an ideal primary standard?
*what is the rationale behind not storing basic solutions in volumetric glassware?
*why there is a need to boil distilled water in the preparation of base solutions?
*why a mixture of NaOH and NaHCO3 is incompatible?
*why there is a need t o boil the solution before reaching the methyl orange endpoint?
You want to rid the water of CO2 from H2O + CO2 ==> H2CO3.
*is it possible to used NaOH as primary standard for HCl and the properties of an ideal primary standard?
No, NaOH is sold commercially and it is relatively pure (probably 98 or 99% or better); however, it picks up water plus CO2 from the air and that makes unsuitable for use as a primary standard.
*what is the rationale behind not storing basic solutions in volumetric glassware?
Strong bases react with the SiO2 in glassware.
I see I missed a couple
*why there is a need to boil distilled water in the preparation of base solutions?
Same a below. You want to rid the solution of CO2 that is dissolved in the water.
*why a mixture of NaOH and NaHCO3 is incompatible?
I don't know that I would call them incompatible. They are incompatible in the the sense that they react with one another but they are not incompatible because of an explosion or some other deleterious effect.
NaOH + NaHCO3 ==> Na2CO3 + H2O
In other words, you no longer have NaOH and NaHCO3. You have water and Na2CO3.
1. The boiling of distilled water is done to remove dissolved gases and impurities that may affect the accuracy of the analysis. Distilled water is generally used to prepare base solutions because it is free from most impurities but may still contain dissolved gases. Boiling helps to remove these gases and ensure that the base solution is not contaminated.
To boil distilled water, you can start by pouring it into a clean beaker and placing it on a heating source, such as a hot plate or a stove. Heat the water gradually until it reaches its boiling point, which is 100 degrees Celsius at sea level. Maintain the boiling for a few minutes to ensure complete removal of any dissolved gases. Allow the boiled water to cool before using it to prepare the base solutions.
2. A mixture of NaOH (sodium hydroxide) and NaHCO3 (sodium bicarbonate) is considered incompatible because they undergo a chemical reaction when mixed together. This reaction produces water, carbon dioxide gas, and a compound called sodium carbonate (Na2CO3). Sodium carbonate is not suitable for use in the desired quantitative analysis of soda ash. Therefore, it is important to avoid mixing NaOH and NaHCO3 in this analysis.
To avoid mixing NaOH and NaHCO3, it is recommended to prepare separate solutions of each compound and use them independently in the analysis.
3. Boiling the solution before reaching the methyl orange endpoint is necessary to remove any dissolved carbon dioxide present in the solution. Carbon dioxide can react with sodium hydroxide (NaOH) to form sodium carbonate (Na2CO3), which can interfere with the accuracy of the analysis. Boiling ensures complete removal of carbon dioxide, minimizing any potential interference with the endpoint determination using methyl orange indicator.
To boil the solution, you can transfer it to a heat-resistant flask and gently heat it on a heating source, such as a hot plate or a water bath, until it reaches its boiling point. Continue boiling for a few minutes to ensure complete removal of carbon dioxide. Allow the solution to cool before proceeding with the analysis.
4. Sodium hydroxide (NaOH) can be used as a primary standard for HCl (hydrochloric acid) if it meets the properties of an ideal primary standard. The properties of an ideal primary standard include:
- High purity: The NaOH used should be of very high purity to ensure accurate and precise results.
- Stability: The compound should be stable and not undergo any degradation or reaction during storage that could affect its concentration.
- Solubility: It should be highly soluble in the solvent used for the analysis to ensure complete and accurate titration.
- Known stoichiometry: The reaction between NaOH and HCl should have a known stoichiometry, meaning the balanced chemical equation should be known.
Before using NaOH as a primary standard for HCl, it is important to verify its purity and stability. This can be confirmed by performing a standardization process using a secondary standard and determining the concentration of the NaOH solution accurately. The concentration obtained can then be used for subsequent analyses.
5. Basic solutions should not be stored in volumetric glassware (such as burettes or volumetric flasks) because they can react with the glass and cause leaching of ions from the glassware. The leaching of ions can lead to contamination of the solution and affect its composition and accuracy during subsequent analyses.
To store basic solutions, it is recommended to use chemically resistant containers such as polyethylene bottles or containers made of other suitable materials. These containers are less likely to react with the basic solution and ensure its stability and integrity during storage.
When using volumetric glassware for basic solutions, it is important to rinse the glassware with the basic solution being used immediately before use to minimize the effects of leaching. Additionally, the glassware should be thoroughly cleaned and rinsed after each use to prevent any residue or contamination.