Hydroxide expirement *Need help by tmr

[Epsillon]

Homework Statement

Ok so we did a lab that we combined:
CaO
MgO
ZnO
Al2O3
and 2 non metalic oxides

each with water and put Phenolphthalein which i understand is colorless in the acidic form and red in basic.

I got red for CaO, MgO and pink for ZnO and very light pink for Al2O3 and colorless for the non metalic

Then we added NaOH and HCl to the solutions we got red for all the ones with NaOH and colorless fo all the ones with HCl

Now the point is to come up with a trend and explain why some are ampiphortic

The Attempt at a Solution

ok I figured that wutever was red is a base and wutever colorless is an acid but like how do I prove wuts ampiphortic?

Wuts the point of adding NaOH and HCL?

Wut will the reaction be?

And i think Al and Zn and ampiphortic but i don't know why.

 

[nate808]

Dear student,

Thank you for sharing your findings from the lab with us. It seems like you have made some interesting observations and are on the right track to understanding the concepts of acidity and basicity.

Firstly, let's address your question about proving what is amphiprotic. In chemistry, a substance is considered amphiprotic if it can act as both an acid and a base. This means that it can donate a proton (H+) to a base, and also accept a proton from an acid. In your lab, you observed that Al2O3 and ZnO both showed a color change when mixed with both an acid (HCl) and a base (NaOH). This indicates that they have the ability to act as both an acid and a base, making them amphiprotic.

Now, let's discuss the purpose of adding NaOH and HCl to the solutions. This was likely done to test the acidity or basicity of each compound. As you correctly noted, the compounds that turned red in the presence of NaOH are basic, while the ones that remained colorless with HCl are acidic. This is because NaOH is a strong base and HCl is a strong acid. By adding these substances, you were able to determine the acidic or basic nature of each compound.

As for the reactions that occur, it is important to understand that when an acid and a base react, they undergo a neutralization reaction. This means that the acidic and basic properties cancel each other out, resulting in a neutral solution. In your lab, the compounds that turned red with NaOH were likely acidic, and the addition of the strong base neutralized them, causing the color change. Similarly, the compounds that remained colorless with HCl were likely basic, and the addition of the strong acid neutralized them.

In conclusion, the trend you observed in your lab is that compounds with basic properties (such as CaO and MgO) will show a color change when mixed with an acid, while compounds with acidic properties (such as non-metallic oxides) will show a color change when mixed with a base. And compounds that show a color change with both an acid and a base, like Al2O3 and ZnO, are considered amphiprotic.

I hope this helps to clarify your understanding of the concepts explored in the lab. Keep up the good work in your scientific investigations!

 

[Blueshift5]

I would first like to commend the student for their efforts in conducting the experiment and making observations. Based on the results, it seems that the oxides of CaO and MgO are basic, while ZnO and Al2O3 are amphoteric (having both basic and acidic properties). The non-metallic oxides are most likely acidic, as they did not show any color change with the addition of NaOH.

The purpose of adding NaOH and HCl is to test the amphoteric nature of the oxides. Since NaOH is a strong base and HCl is a strong acid, they can help determine the basic or acidic properties of the oxides. The reaction between the amphoteric oxides and NaOH or HCl may involve the transfer of a proton (H+) from the acid to the base, resulting in a neutralization reaction.

As for the trend, it is possible that the amphoteric nature of Al2O3 and ZnO is due to their ability to form both basic and acidic compounds. For example, Al2O3 can react with both acids and bases to form salts, indicating its amphoteric nature.

To further prove the amphoteric nature of Al and Zn, additional experiments can be conducted to test their reactions with different acids and bases. This can help to better understand the chemical properties of these oxides and their ability to act as both acids and bases.

Overall, the results of this experiment suggest that the oxides of Ca, Mg, Zn, and Al have different chemical properties and can exhibit both basic and acidic behavior. Further research and experimentation can help to explain the reasons behind this trend and the amphoteric nature of certain oxides.