O-Level Chemistry

PSLE marks the graduation of Primary school students and their entry into Secondary schools as teenagers. Discuss all issues about Secondary schooling here.
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uptas
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Re: O-Level Chemistry

Post by uptas » Thu May 21, 2020 6:35 pm

leeh40 wrote:
Thu May 21, 2020 12:14 pm
Hi,

What is the effect of impurities in melting point and boiling point of a substance? Need your help. Thanks.
Hi lee!

Impurities cause lowering of melting point through the process called melting point depression. For the boiling point, on the other hand, impurities results to higher boiling point of the substance because the number of molecules available for boiling is decreased.

I hope it helps!

If you have more assignments to be assisted with, you can post at this forum. https://www.kiasuparents.com/kiasu/foru ... 1#p1973791
you can also find Q&A and tips and tricks there!

leeh40
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Re: O-Level Chemistry

Post by leeh40 » Thu May 21, 2020 7:43 pm

uptas wrote:
Thu May 21, 2020 6:35 pm
leeh40 wrote:
Thu May 21, 2020 12:14 pm
Hi,

What is the effect of impurities in melting point and boiling point of a substance? Need your help. Thanks.
Hi lee!

Impurities cause lowering of melting point through the process called melting point depression. For the boiling point, on the other hand, impurities results to higher boiling point of the substance because the number of molecules available for boiling is decreased.

I hope it helps!

If you have more assignments to be assisted with, you can post at this forum. https://www.kiasuparents.com/kiasu/foru ... 1#p1973791
you can also find Q&A and tips and tricks there!
Why is the impurities causing the melting point to decrease? For the boiling point, thank you so much Uptas for the rationale.

Will visit the forum you have shared for my next queries. Thanks a lot!

uptas
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Re: O-Level Chemistry

Post by uptas » Sun May 24, 2020 8:13 am

leeh40 wrote:
Thu May 21, 2020 7:43 pm
uptas wrote:
Thu May 21, 2020 6:35 pm
leeh40 wrote:
Thu May 21, 2020 12:14 pm
Hi,

What is the effect of impurities in melting point and boiling point of a substance? Need your help. Thanks.
Hi lee!

Impurities cause lowering of melting point through the process called melting point depression. For the boiling point, on the other hand, impurities results to higher boiling point of the substance because the number of molecules available for boiling is decreased.

I hope it helps!

If you have more assignments to be assisted with, you can post at this forum. https://www.kiasuparents.com/kiasu/foru ... 1#p1973791
you can also find Q&A and tips and tricks there!
Why is the impurities causing the melting point to decrease? For the boiling point, thank you so much Uptas for the rationale.

Will visit the forum you have shared for my next queries. Thanks a lot!
hi Lee,

Impurities can cause a melting point depression because impurity disrupts the crystal lattice energies.

Hope it helps!

leeh40
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Re: O-Level Chemistry

Post by leeh40 » Mon May 25, 2020 10:30 am

Hello Uptas,

Thank you for your patience in answering my question. So, the presence of impurities weakens the lattice, making it less stable. As a result, the compound melts at a lower temperature..now I get it! Thank you so much!👍

chaocheng12
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Re: O-Level Chemistry

Post by chaocheng12 » Mon Jun 01, 2020 8:28 pm

Hello,

How does paper chromatography works in separating mixture of solutes in a solution?


change146
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Re: O-Level Chemistry

Post by change146 » Mon Jun 01, 2020 9:00 pm

chaocheng12 wrote:
Mon Jun 01, 2020 8:28 pm
Hello,

How does paper chromatography works in separating mixture of solutes in a solution?
I think it is measured through the different speeds of different solutes travelling on the paper. It has different speeds so eventually they are separated..

change146
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Re: O-Level Chemistry

Post by change146 » Sat Jun 06, 2020 7:45 pm

Thank you for answer.

rycho12
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Re: O-Level Chemistry

Post by rycho12 » Sun Jun 07, 2020 1:00 pm

Hi,

Need your advice. I'm weak in chemical calculations. Any tips on how to improve?

cysean009
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Re: O-Level Chemistry

Post by cysean009 » Sun Jun 07, 2020 2:05 pm

rycho12 wrote:
Sun Jun 07, 2020 1:00 pm
Hi,

Need your advice. I'm weak in chemical calculations. Any tips on how to improve?
Perhaps part of the tips would be to master chemical formulas and balancing of chemical reactions since those are essential factors in chemical calculations.

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