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Teacher's response to Hong Feng Question 

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Teacher's response to Hong Feng Question 

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25 degree celsius is a rough gauge. If the boiling points of the miscible  liquids are too close together,  there are complications due to evaporation of either liquids, your distillate would not be pure.

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Teacher's response to Yew Lim, Hong Feng and Ethan's Question 

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Teacher's response to Yew Lim, Hong Feng and Ethan's Question 

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You could use liquid such as oil for gases that are not soluble in oil.

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There is no gas that is denser than water

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Is crystalization able to be done at extremely high or low temperatures?

Teacher's response:
Crystallization occurs generally at normal room temperature or lower than that. I am not sure about extreme high temperature and low temperature.

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Can we use other liquids such as alcohol?

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Is water the only liquid that can be used?

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What is the maximum amount of any substances that can be gotten through Crystallisation?

Teachers : Depends on the amount of dissolved substances

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Simple Distillation does not work when the boiling point of two substances is less then 25 degrees celsius. Because they do not get separated and purified completely, how so?( why 25 degree celsius?)

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Why is filter paper used in Paper Chromatography? Instead of Normal Paper

Teacher's response :
Normal paper does not absorb the solvent as well as filter paper.

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Other then water, is there any other liquid that could replace water?

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How do we seal the flask without air getting in? Will air getting in affect the results?

Teacher's response
Yes

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Does the material of the ballon affect how Ling the ballon can float

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Can all gases make the ballon float? Teacher's response : No

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What method is used for sodium chloride and sulfur dioxide

Teacher's response :
Sodium chloride is not a gas at room temperature. So not using any of the gas collection methods. Sulfur dioxide is denser than air. Use downward delivery method.

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Why are all gases less dense than water?

Teacher's response : Gas particles occupies more space than liquid water particles. Thus all gases are less dense than water.

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Why is the gas syringe method suitable for all gases?

Teacher's response :
Depends on your usage of the gas collected, if you need your gas to be very pure, then gas syringe method is not suitable to collect the gas. But if you using it to measure the volume, then gas syringe method is suitable.

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What is the difference between upward displacement and downward displacement?
How does the movement of gases vary?

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Off the 4 methods which is most common in daily lives

Teacher's response
These methods are used in chemistry lab.

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What if other gases are put into balloons will they be still able to float

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If the gas is soluble in the water do we need to change the liquid used in the over water method ?

Teacher's response:
Can change the liquid to oil. Gases that not soluble in water are usually soluble in organic solvent such as oil.

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If we use the over water method to collect the gas and the gas is denser than water what will happen to the gas

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1) Make use of the Boolean Algebra AND and inverted commas
e.g  Google search engine will search for exact phrase of simple distillation and filtration if you type  "simple distillation" AND "filtration"
2) Make use of the "video" tab of the search results to learn concepts more effectively.

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Raymond Ng - Help for workbook worksheet 2

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Raymond Ng - Help for workbook worksheet 2

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Some help for your workbook worksheet 2
Section B : structured questions

Question 1c
Search"Calculate Rf value"

Question 2c
https://www.minichemistry.com/determining-if-a-substance-is-pure.html

Section C : Free Response Questions

Question 1
Search "Filtration" and "Crystallization" and understand these two process.

Question 2
Search videos on "distillation" and "fractional distillation" and find out the difference between these two to answer this question

Search images on "heating curve of fractional distillation" to answer (di)

Search on "separating funnel". to answer part (e)

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Watch the below videos about some of the  important Separation techniques that you need to know and post questions that you have after watching the videos.

Paper Chromatography
https://www.youtube.com/watch?v=PvHvx7k7UPU

Calculating Rf values

Simple distillation
https://www.youtube.com/watch?v=V5ep0-ojPGw
Crystallisation
https://www.youtube.com/watch?v=nztV4w0DtOo

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Mr Raymond Ng -Measurement and Experimental Techniques

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Mr Raymond Ng -Measurement and Experimental Techniques

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Watch the video in this link about collection of gases.
https://www.youtube.com/watch?v=EOBRZxn4JIA
Do you have any questions you want to ask?