Non ideal behaviour of gases

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Non ideal behaviour of gases | 1st year chemistry chapter 3
Non ideal behaviour of gases | 1st year chemistry chapter 3

Gases deviate more from the general gas equation at 0oC and deviate to less extent at 100oC. Why?

Ans. General gas equation is for ideal gases (which have no forces of attraction). At 0oC molecules are close to each other and have strong attraction, while at 100oC molecules are far away from each other and have very weak attractions. Therefore, Gases deviate more from the general gas equation at 0oC and deviate to less extent at 100oC.

Hydrogen and helium are ideal at room temperature, but SO2 and Cl2 are non-ideal. How do you explain it?

Ans. Molecules of hydrogen and helium are very far away and have no force of attraction at room temperature. While molecules of SO2 and Cl2 are very close and have force of attraction at room temperature. Therefore, Hydrogen and helium are ideal at room temperature, but SO2 and Cl2 are non-ideal.

Why the gases deviate from ideal behaviour at high pressure and low temperature? OR do you think that some of the postulates of KMT of gases are incorrect?

Ans. At high pressure and low temperature molecules of gases are close to each other and have forces of attraction. Moreover, actual volume of gas is not negligible as compared to the total volume of vessel. Therefore, we can say that some of the postulates of KMT of gases are incorrect.

Water vapours do not behave ideally at 273 K. Why?

Ans. At 273K (0oC) molecules of water vapours are close to each other and have forces of attraction. So, Water vapours do not behave ideally at 273 K.

Give two causes for deviation of gases from ideality?

Ans. The two causes for deviation of gases from ideality are

       i.            There are no forces of attraction between molecules of gas.

     ii.            Actual volume of gas is negligible as compared to the total volume of vessel.

SO2 is comparatively non-ideal at 273 K but behave ideally at 327 K. Why?

Ans. At 273 K (0oC) molecules of SO2 are close to each other and have forces of attraction. While at 327 K (54oC) molecules of SO2 are very far away from each other and no forces of attraction between them. Therefore, SO2 is comparatively non-ideal at 273 K but behave ideally at 327 K.

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