Entry 9

Hi everyone!

Hope you'll have had a good weekend! Anyway, i am back to share with you more about my laboratory lesson in school today.

Today was about crystallization. 
Introducing you to crystallization....
It is solution is the most common method used to purify soluble solids. There are many ways to carry out crystallization  The seeding method allows you to grow a large single crystal, others allows you to grow many crystals at a time. By controlling the variables such as cooling rate and evaporation rate, the size and shape of the crystals can be controlled.

In order crystallization to take place, there are certain conditions that need to be met.Firstly, the solid in question must be soluble in water. Secondly, the solubility of the substance should change with change temperature. Thirdly, the solution used should be saturated with solution.  Typically, the solution is heated to form a hot, saturation solution. The heating allows for excess solvent to be removed via evaporation. as the hot saturated solution cools. The dissolved solid appears as crystals as the solubility of the solute decreases with decreasing temperature. This means that as temperature of the solution drops less solute can be dissolved in the solution. The excess solution will then appear in the solution in the form of crystals.

After the entire experiment, i learned that crystals obtained by rapid cooling, meaning that the solution in the boiling tube is placed in a beaker of cold water. The crystals that are obtained are smaller and irregular. Crystals obtained by slow cooling, meaning it is heated slowly by hot water will result in becoming bigger and in a more regular shape.

This is how Copper (II) Sulphate looks like.

Some steps of the crystallization process.

Conclusion
Crystals formed by rapid cooling are smaller & less regular as compared to slow cooling.

Some questions to think about....

1. How can you obtain more crystals from the cooled copper (II) sulphate solution?

• Add more water to dissolve more copper sulphate. 
• Add more copper sulphate
• Apply slow cooling instead of rapid cooling. 

2. Suggest 2 reasons why in crystallization method we should stop heating before all the solvent evaporated. 

• To prevent the copper sulphate from decomposing 
• There will be soluble impurities will be left behind. 

We also learned more about sublimation. In which, the solid turns from solid -> gas without passing through liquid. An example would be iodine (solid). When placed with sand and a funnel placed over it, it will emit "purple" coloured gas. 

Sublimation set-up. 

Result of sublimation of iodine solids. 

After that, we continued doing our online activity called Are you good enough for it? Soon after that the class ended :) Thank you for reading!! 

Entry 8

Todays Lab lesson...

I learned about simple distillation today.
Generalization: Systems have elements that interact with each other to perform a function. Systems follow rules.

Distillation
Simple distillation is used to purify a liquid by separating the solvent from the dissolved solutes.
1. It involves 2 stages and both are physical state changes.
2. Stage (1): The liquid or solution mixture is boled to vaporise the most volatile component in the mixture (liquid ---> gas).
3. Stage (2): The vapour is cooled by cold water in the liebig condenser to condense (gas ----> liquid) it back to liquid (the distillate) which is collated.

This is a diagram of simple distillation 
*Note that the distillate is pure water.

For my experiment, we used Coca-cola to be the solution. after the experiment was was left behind from the distillation were sugar, carbon and caffeine.

Some questions to think about...
1. Why does the water enter the condenser from the bottom and exit from the top?

This is to ensure that most of the water vapour is condensed and collected as liquid. If cold water enters from the top, it will not fill the condenser.

2. What is the function of boiling chips?

It is to make boiling point smooth.

3. Why is the bulb of the thermometer placed next to the sidearm?

This is to allow us to measure the temperature of vapour in order to identify the boiling point of the distillate.

Application

• Distillation can be used to purify water because the dissolve solids will not evaporate with the steam. 
• It can also be use to separate two miscible liquids with different boiling point. But it is ineffective if the boiling points of liquids are relatively close. 
• Distillation is not the only way we can obtain pure drinking water. NEWater production make use of two main separation steps- micro filtration and reverse osmosis. 

Isn't it so fascinating to see how pure water is being obtained!! I think that todays lab lesson was extremely fun and engaging it was also an eye-opener. 

We also learned additional information about fractional distillation. Both distillation methods are similar because both involve coiling and condensing and require heat energy. However they are also different as the simple distillation method has no fractionating column, however the fractional distillation has a fractionating column. 

This diagram is a setup of fractional distillation. The fractionating column can be seen above the round-bottom flask.  

Simple distillation and fractional distillation are used to separate the solvent from the solution(simple distillation), for fractional distillation it is to separate 2 miscible liquids. 

During the 1st part of the lesson i also finally got to experience handling chromatography paper and carry out an experiment!! (It was super exciting and interesting!) 

This was the colour i got from mixing distilled water with green food dye! A really pretty colour. Apparently, some lucky people got to have some yellow and pink on their chromatography paper too. 

For the second part of the lesson we did an online class activity called "are you good enough for it?" We had to work in groups of 4 and plan a suitable procedure for separating all the chemicals in the given mixture. My group is still in the midst of creating our powerpoint slide which one of our group members is in charge of. The other 3 of us are in charge of researching on the different chemicals. 

1. Iron filings

2. Iodine (sublimes when heated) 

3. Copper Sulphate

4. Calcium sulphate

5. Ammonium chloride (sublimes when heated) 

6. Lead (II) Bromide

For every single chemical we are suppose to find out its physical appearance, magnetic attraction, solubility in water and solubility in organic solvents. After that we also need to create a flow chart to show our proposed separation procedure. It is very interesting but also brain racking when we are unable to find out things about the chemicals. 

Alright, that's it for today, thank you for reading my blog! 

Entry 7

Hi everyone!

Today was a lesson on Separation Techniques. We were given a stack of notes that had slides printed on it to aid us in learning more about it. Today the main focus was on the procedure of Chromatography.

Chromatography

• The more soluble the ink is the faster it will move upwards.
• Mobile phase is the solvent, it shows how fast it travels up the paper. 
• More soluble = travel up the chromatography paper faster. Less soluble = travel up the chromatography paper slower.
• Take note that only one drop of ink sample should be placed on the chromatography paper as if too much is placed, it will affect the accuracy and reliability of the results. 
• Solvent must be below the  pencil line. 
• Drop the ink right below the pencil line. 
• Solvent front is the maximum height the solvent can travel 

* When solvent is heated, the solubility will increase the ink spot will move up.

After that we moved on to Simple Distillation. 

• Distillation helps to separate water from other solutes, like salt. It is 100 % pure. 
• Distilled water is not good for consumption for human body as our body requires certain combination of salt etc. and cannot be 100% pure. 

We were given the task to find out the answers to these questions before our Lab lesson tomorrow. These questions came from observing the diagram of a simple distillation experiment....

• What do you mean by smooth boiling?
• What are solutes?
• Purpose of condenser? 
• Purpose of boiling stones?
• The position of inlet & outlet? 
• Why is the thermometer placed that way? 

We also got back our quiz results :) 

Thank you for reading! 

Entry 6

Hey :)

Today we had two parts to the lesson. The first part was a summary to the chapter on Elements, Compounds and Mixtures and we also started on a new chapter: Separation Techniques. The second part of the lesson was a Formative Assessment (FA) that allowed the teacher to gauge how much we understood from the first chapter Elements, Compounds and Mixtures.

Summary

Mixtures

• 2 or more substances added together and are not chemically joined together. 
• 2 elements 
• Mixture of 2 compounds 
• 1 element & 1 mixture. 

e.g H2O & CO2

      H2*NH2  (1 element, 1 compound) 

• Filtration, fistillation, chromatography 
• electricity/chemical reactions. 

Alloy

- Mixture of metals and other elements 

- Stronger 

e.g Bronze, stainless steel 

Steel

- Iron + Carbon 

Stainless steel 

- Iron, chromium, carbon

Brass

- Copper, Zinc

Bronze

-Copper, Tin

Separation Techniques

• Mixture 
• Physical Methods

Filtration

One substance soluble, one not soluble in water. 

Why PURE? 

• Health hazards
• Medicine: water, food etc. 
• Characteristics: properties, melting point, density 
• Identification: test to prove, separate first 
• Production of useful substances 
• No such things called 100% pure there can only be 99.99999% pure. 

Paper Chromatography

• Separate a mixture of solutes with different solubility & degree of absorption/ 
• More soluble->move further up
• Not so soluble-> stay below
• This method uses a solvent moving over a porous/absorbent medium (e.g paper/gel) to separate. 
• dye/sugar (glucose/fructose)

This is an example of what experiment i will be doing this friday in the lab session! Definitely eager to share my experience with you! As the solvent travels up the paper, the dye dissolves. Some dyes are less soluble, so they travel even faster upwards. 

Take note! 

1. Dont let the ink touch the solvent as it will soak up very quickly. 

Separation depends on....

• solubility of the dyes in the solvent. 

That will be all for the first part of the lesson! It was very interesting and enjoyable!! The next part was just our test about the first chapter. I felt the test was not that straightforward but doable :) Thank you for reading!! Hope that you will continue visiting my blog! 

HAHA!! 

Entry 5

Hey!

Today i learned about the Atomic Structure! An Element is made up by Molecules. An Element consists of Atoms and Sub-atomic particles this makes up the Periodic table. The sub-atomic particles are the protons, neutrons and electrons. Everyone/ Everything have sub-atomic particles just that they have different number. 

This is a diagram of an atom. Protons and Neutron make up nucleons. The second diagram shows the different charges of protons, neutrons and electrons. Proton is represented by the symbole (h). So its charge is h+. Electrons is represented by the symbol (e), so its charge is (-e). Neutron has no charge.

Electrons move about freely and randomly. Shells and orbitals put in place to assist studying. 

amu=atomic unit mass/relative mass. Electrons do not deviate due to (-e), proton is (+h). Negative and positive charge attract each other. 

This diagram also shows the respective relative mass of proton, neutron and electron. 

Atoms are electrically neutral as they have equal number of (+h) proton and )-e) electron. Hence, proton = electron. Atoms of different elements have different proton number. Each proton number is unique to a specific atom only. 

Nucleon number (proton+neutron)= mass number. 

E.g 12C (12=nucleon, 6=proton.) Since proton+neutron=nucleon. Nucleon-proton = neutron. So the neutron number is 12-6=6. Since the atomic mass of both proton and neutron is 1 respectively, its totally relative mass will be....

6p=1*6=6

6n=1*6=6

Total relative mass=6+6=12

Alright! This will be all for today! Thank you :) 

Entry 4

Hi!

Today i had another laboratory lesson! It was really really interesting and definitely a very good hands-on experience. Today's practical was on Comparing Element, Compound and Mixture. 

Our aim was
1. to observe and compare the properties of compounds and mixtures made up of the same constituent elements.
2. Thus, infer some common characteristics of mixtures and compounds that can be used to distinguish them.

There were 2 parts to the experiment. The first part being (A): Investigating a mixture of elements. (B) Mixture or compound? Throughout the entire experiment we used two elements, that being Iron and Sulfur. We observed the appearances of both. The appearance of the Iron Filings was that it was silvery-grey and was in solid state. The appearance of sulfur powder was that it was yellow/ bright yellow and was also in solid state.

This was our experimental plan...
1. Place a spatula of iron filings and a spatula of sulfur powder on a piece of filter paper. Mix them together.
2. Move a magnet under the filter paper and observe if the magnet separates the mixture of elements.
3. Add the iron and sulfur mixture into a test tube of water. Stir the mixture and then let it stand for a while. Draw and label what you see.

That was for Part (A). After conducting the experiment, we answered some questions.
1. To form a mixture can the iron filings and sulfur be mixed in any proportion?
2. Feel the mixture(from the bottom of the filter paper). Does it feel warm?
3. Does water separate the mixture of elements?
4. Do the iron filings and the sulfur act as separate substances or a single substance with water?

Answers...
1. Yes, it doesn't matter because they are going to be mixed.
2. It remains cold, mixing the elements does not result in any heat change.
3. No
4. Separate substances.

Note that both elements are insoluble substances, so they are unable to dissolve in water.

In conclusion:
The substances in a mixture can be mixed in any proportion. When a mixture is formed, heat and light are not usually taken in or given out. The mixture can be separated by physical means. The mixture has/retains the properties of its constituent substances.

*Constituent= Individual substances that make-up the mixture*

Moving on to Part (B)...

1. Mix one spatula of sulfur and half a spatula of iron filings in a crucible
2. Cover the crucible with a lid and heat for 10 minutes using strong flame.
3. When the crucible has cooled down, open the lid and observe the residue left.
*** Sulfur burns in air readily to produce a poisonous gas, sulfur dioxide. 
->Keep the crucible covered during heating and remove the lid only after the crucible has cooled down 
-> Do not mix too much iron filings and sulfur (increases amount of poisonous gas produced) 

After the crucible has cooled down, i observed that the residue left was hard and black in colour, it was no longer in separate substances but mixed compound.

Conclusion 

Three things to note from this experiment
1. Properties of the compound have different physical properties from its constituent elements.
2. A compound cannot be separated by physical means.
3. A chemical reaction takes place when a compound is formed, when there is an energy change.

We were also given more enrichment questions...
For example: You are given a solid mixture of common salt, sulfur powder and iron filings. Describe how you will separate these 3 substances.

After much thinking and some background knowledge, i came up with this answer. Firstly, separate the iron filings first using a magnet. Then, add water to the mixture of sulfur and salt.The sulfur substance will float to the top leaving salt water. Use a filter to separate the salt water from the sulfur through a process called filtration. After that, reheat the salt water till it reduces to salt solid substance again. Lastly, Reuse the filter paper to squeeze out the water from the sulfur substance.

*A filter is used to separate insoluble and soluble substances. 

This was what i learned for the day! Thank you for reading again:)

Entry 3

Aloha! :)

Today i learned more about elements! I would like to share with you all an interesting fact: apparently, graphite and carbon are non-metals that have the ability to conduct heat! Isn't that so cool? At least i think so :P

Alright, moving on to some theory of this chapter. There are some definitions that are important to memorize and know well especially for my examinations in school.

The two words that are important...
1. Malleable
Pure metal is soft. Hence it is able to be bent, metals are known to be very rigid and hard (unable to be bent so effortlessly). However, that only happens when other mixtures are mixed together with pure metal, making it so hard and strong.

The second one:

2. Ductile
This means that the pure metal can be drawn out into a thin wire.

*The density for metal is also high as its atoms are closely packed*

Now for an analogy: 

The picture above are paper clips joint together to form a shape. This is considered as an element.

This picture above is a paper clip that is on its own is known as an atom. An atom is the smallest that an element can go to and still be functional. This paper clip for example can still be broken down into smaller pieces, however, that does not mean that it is still functional.

Definition of an element and atom

• An element is a substance made up of one type of atom. 
• An atom is the smallest particle of an element that retain the chemical properties of that element.

An atom of element A is different from an atom of element B, this is a very important concept that has to be known. 

Difference between an atom and molecule

• An atom is the smallest particle of an element that retain the chemical properties of that element. 
• A molecule is a group of two or more atoms that are chemically combined (joined together).

Atoms that have the stable configuration are labelled noble gases or also under the group VIII in the periodic table. 

The periodic table 

The metals and non-metals in the periodic table are separated.

 This picture shows the features of the periodic table.

The periodic table consists of 7 periods of elements (shown by the different colours), numbered 1 to 7. Each element in a period has a proton number which is one less than the element after it. It is arranged in increasing atomic masses.

The periodic Table has 8 groups of elements, numbered from I, II etc to 0. They run vertically from top to bottom.

I also learnt about metalloids, metals and non-metals. They exhibit both metallic & non-metallic properties/ characteristics. Example: silicon as chemical properties similar to non-metals but exhibit properties such as electrical conductivity like metals.

Alright, that's all for today! Tomorrow i will be having hands-on experiment/lab lessons, its going to be so exciting! :))

Entry 2

Hi everyone! 

Today was my first Chemistry Laboratory lesson! It was very interesting and definitely very enriching. We had a 2 hour lesson in the lab, but we split it into 1 hour of hands-on experiments and the other hour was on researching. 

The first thing that we learnt was the main gist of the entire lesson and is a very important skill needed. This skill was how to go about lighting up the bunsen burner safely and learning the theory portion of it too. An interesting fact: Guess who invented the bunsen burner? It was Robert Bunsen! 

We also got to wear the safety goggles for the first time!! It wasn't that comfortable but i soon got quite used to it. The safety goggles is very important as it protects our eyes from getting hurt incase of any spillage etc.

 We moved on to gather at the front of the lab to watch how our Chemistry teacher went about lighting up the bunsen burner. I learnt that there are three parts to the flame. 

1) The tip of the orange flame. 
2) The tip of the blue flame (which also is the hottest part of the the entire flame) 
and lastly
3) the inner most core of the blue flame.

I also learnt that when you open the air hole partially oxygen rushes into it causing the orange flame to change into blue flame. The blue flame is known as the non-luminous flame. Though not luminous it is very hot. The orange flame on the other hand is luminous yet not as of that high a temperature compared to the blue flame. 

After returning back to our seats, everyone had a chance to light up the bunsen burner using the correct method. Once the allocated amount of time was up, we moved on to answering some questions. Soon after that, the teacher went through with us the questions, and also explained in detail what dependent, independent and controlled variables are. 

That was all for the experiment today. 

The next hour we spent the time researching on the different elements that we had adopted. My element that i adopted was Sulphur. Sulphur is also commonly known as sulfur. It is a non-metal and is soft, pale yellow, odorless, brittle solid. It is a good insulator of heat and electricity. It has a boiling point of 444.7 degree Celsius / 717.9 Kelvin and a  melting point of 115.2 degree Celsius / 388.4 Kelvin. It has a hardness of around 1.5-2.5.  Sulphur’s main commercial use is as a reactant in the production of sulfuric acid (H2SO4). Sulphuric acid is the industrialized world’s number one bulk chemical, required in large quantities in lead-acid batteries for automotive use. Sulphur is also used in the vulcanization of natural rubber, as a fungicide, in black gunpowder, in detergents and in the manufacture of phosphate fertilizers. Sulphur is a vital element for all forms of life. It is a component of two amino acids, cysteine and methionine.

After researching on it, we collated all the information on a google doc for the entire class to share. We were also given a worksheet to attempt.

Alright, that's all for today, thank you for reading! :)

Entry 1

10 January 2013! 

Today was the first official lesson that we started to learn more about Chemistry. We started on the Chapter of Elements, Compounds and Mixtures! We did a class activity and were split into different groups of 3.  Through this activity we learned how to classify the different particles into different categories based on our observation. There are many different ways to classify them, for example: same colour, same amount of particles, same shape etc. After completing that, we moved on to guess how other groups had classified the exact same set of particles. I think it was a very enriching experience, something that was new to me. Once we were done, we had to answer some questions on this activity:

1. Which one(s) do you think comes from the same type of substance? Why?
2. Which two do you think come from the same substance? Why?
3. Which one is/are gases? 
4. What do you think each particle represents? 

From answering the questions and asking questions, i also learned that when heat is introduced to do particles, the particles will move causing the atoms to be in a "distorted" manner instead of a uniform row. I also learned that the more number of particles occupying a certain space, the greater the density. 

I asked a question: what is the difference between particles and atoms. Apparently, "particle" is a broad term for atoms and molecules. 

That's all for today, thank you for reading!!