Standerising NaOH: How to Do It & What Concentration of HCl

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In summary, the conversation discusses the need to standardize a 0.1moldm-3 solution of NaOH with HCl acid for a chemistry practical. The reason for this standardization is due to the fact that NaOH pellets have no definite composition and the concentration of the solution can change over time. However, the participants are unsure of why and how to standardize and what concentration of HCl to use. They seek advice and further information on the topic.
  • #1
Bunting
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I am doing my chemistry practicle and my tecaher has told me that I need to standerise my 0.1moldm-3 solution of NaOH with HCl acid. But I don't know why or how, or what concentration of HCl. Does anyone have any ideas pls?
 
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  • #2
Why? NaOH pellets have no definite composition --- you can't make up solutions by weight to better than a few percent uncertainty, and, once made up, it's a base, it absorbs CO2 from the air --- so, no matter how careful you are about keeping it closed, the concentration changes over time. This much information is not as well stressed during instruction as it should be. You get this much for free.

Since this is more in the category of a HW problem, now, you can tell us what you do know, how much instruction you've had, what lab manual you're working from, how much success you had with the acid-base titration exercises, and what you think is the place to start on this problem. 'Kay?
 
  • #3


Standerising, also known as standardizing, a solution of NaOH with HCl acid is a common practice in chemistry laboratories. It involves determining the precise concentration of a solution by titrating it with a known concentration of another solution. This process is important because it ensures that the concentration of the solution being used in experiments is accurate and consistent.

To standardize your 0.1moldm-3 solution of NaOH, you will need to titrate it with a solution of HCl acid of known concentration. The concentration of HCl to use will depend on the volume of NaOH solution you are using and the desired accuracy of the standardization. In general, a concentration of 0.1moldm-3 or higher is recommended for accurate results.

The standardization process involves carefully measuring out a known volume of your NaOH solution and adding it to a flask. Then, a few drops of an indicator, such as phenolphthalein, are added to the flask. The HCl solution is then slowly added to the flask while swirling until a color change is observed. The color change indicates that the titration is complete and the volume of HCl solution used can be used to calculate the concentration of the NaOH solution.

It is important to note that the standardization process should be repeated at least three times to ensure accuracy and precision. This means that you will need to use a new flask and fresh NaOH solution for each titration. Additionally, it is recommended to use a burette for accurate and precise measurements of the HCl solution.

In summary, standardizing a solution of NaOH with HCl acid is an important step in ensuring the accuracy and consistency of your experiments. The concentration of HCl to use will depend on the volume of NaOH solution and desired accuracy. It is important to carefully follow the steps of the standardization process and repeat it multiple times for accurate results.
 

1. How do I standardize NaOH?

To standardize NaOH, you will need to perform a titration with a known concentration of acid, such as HCl. First, measure out a specific volume of NaOH solution using a volumetric flask. Then, add a few drops of an indicator, such as phenolphthalein, to the flask. Slowly add the acid solution to the NaOH solution until the indicator changes color. Record the volume of acid used, and use this information to calculate the concentration of the NaOH solution.

2. What is the purpose of standardizing NaOH?

The purpose of standardizing NaOH is to determine its exact concentration. This is important because the concentration of NaOH can vary due to factors such as storage conditions and evaporation. Knowing the exact concentration allows for accurate and precise results in experiments and other scientific processes.

3. What concentration of HCl should I use to standardize NaOH?

The concentration of HCl used to standardize NaOH will depend on the concentration of the NaOH solution. It is recommended to use a concentration of HCl that is close to the expected concentration of the NaOH. For example, if you expect the NaOH to be around 0.1 M, then you can use a 0.1 M HCl solution for standardization.

4. Can I use any acid to standardize NaOH?

Yes, you can use any acid with a known concentration to standardize NaOH. However, it is important to choose an acid that will react with NaOH in a 1:1 ratio, such as HCl. This will make calculating the concentration of NaOH easier.

5. How do I know when the titration is complete?

The titration is complete when the indicator changes color. For example, phenolphthalein will change from colorless to pink in the presence of excess base. You should also see a stable color change that lasts for at least 30 seconds. It is important to add the acid solution slowly and swirl the flask to ensure an accurate endpoint.

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