#5

EXCESS ZINC CARBONATE IS ADDED TO HYDROCHLORIC ACID IN THE PREPARRATION OF ZINC CHLORIDE SALT. 

(i) Write an ionic equation for this reaction


ZnCO3 (aq) + 2HCl (aq) à  ZnCl (aq) + H2O (l) + CO2 (g)








(ii) Why is excess Zinc Carbonate used? 


This is to ensure that ALL Zinc Carbonate has completely neutralized with the acid before we filter out the excess unreacted solid from the salt solution.








(iii) Briefly explain how the Zinc Chloride Crystals can be obtained


Excess ZnCO3 will be added to HCl until a black, insoluble unreacted solid can be seen. Filtration is carried out to remove the excess unreacted solid. The solution of reacted and neutralized solution then undergoes evaporation to remove the water and make a saturated salt solution. The hot saturated solution is left to cool to obtain the zinc chloride crystals.

#4

SULFURIC ACID IS TITRATED WITH POTASSIUM HYDROXIDE IN PREPARATION OF POTASSIUM SULFATE SALT

(i) Explain why this method is recommended for the preparation of the salt

Pottasium Sulfate is a Group (I) salt and it is soluble. The solutions used are all also colourless, and because of this we would need an indicator (provided in titration method) to indicate the end point of neutrolization between the acid and alkali before preparing the salt.

(ii) Write an ionic equation for the reaction

H2SO4 (aq) + 2KOH (aq) à K2SO4 (aq) + 2H2O (l)

#3

An unknown green solution is heated with a piece of aluminium foil and sodium hydroxide solution

(i) The gas produced turns damp red litmus paper blue. Name the gas evolved.

Ammonia gas

(ii) This is a confirmatory test for an anion. Name this anion.

Nitrates.

(iii) Give a possible cation which gives the green solution.

Iron(II) ions (Fe 2+)

#2

AMMONIUM SULFATE IS HEATED WITH SODIUM HYDROXIDE

(i) Write the chemical equation (including state symbols) for the reaction


 (NH4)2SO4 (aq) + 2NaOH (aq) à   NA2SO4 (aq)+ 2H2O (l) + 2NH3 (g)

(ii) Describe a test for the gas.

Hold a piece of damp red litmus paper over the mouth of the test tube. The ammonia gas will turn the damp red litmus paper blue indicating its presence. Ammonia hydroxide is formed on the damp red litmus paper, as it has became an alkali, it turns the damp red litmus paper blue

#1

Zinc Nitrate (NO3-) reacts with Aqueous Ammonia (NH4OH) to form a SALT and a BASE

(i) Name the salt and the base

The salt produced in this reaction is Ammonium Nitrate (NH4)2NO3
The base formed is Zinc Hydroxide (ZnOH)

(ii) Describe the observations for the reaction

The previously-colourless solutions remain colourless (due to the formation of Ammonium Nitrate) and there is a presence of white precipitate (the insoluble Zinc Hydroxide)

(iii) Write a chemical equation for the reaction (including state symbols)

ZnNO3 (aq) + 2NH4OH (aq) à Zn(OH)2 (s) + (NH4)2NO3 (aq)


(iv) Write an ionic equation for the reaction


Zn2 + (aq) + 2OH- (aq) à  Zn(OH)2 (s)

MY PROFILE.

Hello, I'm sorry but I dislike lengthy and super informative profiles because they somehow tick me off in their own little way. I think that since this is my own blog, and as Mr Tan repeatedly said, I have to treat it like my own blog.

Well, I think that I should design this blog according to my preference! Nonetheless, I wouldn't want to lose marks by not making a profile so I decided to write it in a post instead! (:

My name is Ysabelle Torres and I'm 14 years old.

My birthday falls on every 2nd of October

I study in Yuhua Secondary School

I'm in secondary 3 and my class is 3E5!

I was from Boon Lay Garden Primary School and my CCA was Brownies there.

Yea, you can start laughing now.

 

Zees is my vb clique! I'm somehow closer to these 4 people during training and they're the ones that I go to when I'm having problems with my skills! HEHEHE, we've been through thick and thin together and we are all there for each other! We've been together since sec1! 

and this is yet another clique! Founded when we were in sec1! They're the closest to me when in class! I love spending time with them but sadly, we've drifted apart ever since being segregated into different classes in sec3. I really miss the fun times we had when we were in lower sec though!!! :(

AND THIS IS B'GIRLS 2010.

I've been through a lot with this team and we always have funny and weird moments together! Sadly, the sec4s this year had already passed out so that they can study for their O'levels! I miss them soooo much! Especially the times when we were all eating meals after training and gossiping and laughing! Plus the times when we're all going home from our friendly matches and I will jump on Kahman's back :( I hope they can come back after their O's! 

and this is the Durians! HAHAH, since the Bgirls'10 had so many people, we were split into 2 groups! The Durians and the Pineapples! We managed to go into the knock-out round! We sadly lost to Presbyterian High's 'Red' team! 

And oh btw I didn't wear the wrong jersey!!!! I was required too! :P

and this is my bruddaaaaaaaaaaaaaaaaaaaa :D hehehehe! 

COMMENTS! (:

Michelle (30) - HEY! I think that your answers are very summarized and is suitable for quick revisions! However, you should perhaps include more information in your answers. Your font is good and easy to read, so that's a plus. Your blog skin is neat and tidy too! Include more punctuation in-between so that your sentences won't be too long! :>

Aleen (27) - Okay, your blog is super informative and very wordy! However, I think that you should style your paragraphs in a way that it doesn't look SUPER wordy because; well, people -especially teenagers in our age group- will surely feel the need to sleep when they see like a huge chunk of words in one paragraph! HAHAHA, maybe try breaking them down into more paragraphs and perhaps adding underlines, highlights and colours so as to make it look more 'teenager-friendly'! :>

Mingsiew (25) - I like your answers for the question regarding the isotopes. However, for those questions about the ions and atoms; I know that you can write more! HEHE, maybe write more information or something! (: Other than that, you pretty much nailed down the important points! Good work! :>

Chelsea (08)  - Yo bro! Hehehe, you also have the important stuff written down, but I feel like your answers could have been better with more information! Just crap a lot :P MAYBE it'll gain you a few extra points seeing that you've went great lengths in understanding the subject! HAHA, I know that you rushed your answers, hence they're quite short! Anyway, still good answers! :D

#1

What does an atom look like? What are the sub-atomic particles inside it?

(Talk about protons, neutrons, electrons, etc...)

Atom: The smallest particle that has some subatomic particles.

Subatomic particles: electrons, protons, neutrons

Picture of an atom:

An electron is negatively charged. It has a relative charge of -1 and a relative mass of 1/1840. It's mass is much lighter than than that of a proton and neutron. Electrons are the smallest part of an atom. It is found in the atom's shells. A maximum of 2 electrons is found in the first shell. 8 electrons in the second shell and so on. The 4th shell can contain 18 electrons. The electron is what controls the charge (either positively or negatively) of the atom. An atom lose or gain electron(s) in order to achieve stability.

The nucleus of an atom is made up of the proton and the neutron. The sum of the neutron and proton number is called the atomic mass number. In other words, the nucleon number.

The number of protons in the nucleus of an atom is called the proton number/atomic number. The relative charge of protons is +1 and their relative mass is 1. It's mass is the same of a neutron.

For the neutron, it's relative charge is -1 and it's relative mass is 1. (Mass same as that of proton)

#2

Draw the atomic structure of a sodium atom and 

a sodium ion....

Explain why you draw it this way.

Picture of a sodium atom! (:

The electronic configuration of sodium is 2.8.1 due to the number of it's protons; 11. The number of electrons and protons is the same! 

As the 'rules' say. A maximum of 2 electrons can be contained in the first shell. A maximum of 8 in the 2nd and so on. However as shown in the picture above, there's an 'extra' 1 electron in the 3rd shell. 

What will happen to that 1 extra electron will be explained in the following..

And this is a Sodium ion

So yup, the third shell was kinda 'taken away' because the last valence electron was given out. And as I mentioned before, an atom becomes positively charged when it gives away electrons. As for this case, one electron is given out, so sodium ion has a charge of +1. The electronic configuration becomes (2.8) as it has gained stability by giving away it's one valence electron.

#3

Draw the atomic structure of a sulfur atom and a sulfide ion

explain why you draw it this way.

This is a picture of a sulfur atom.

As you can see, the configuration for it is 2.8.6! When added-up, the number of electrons is 16, equals to the number of protons. The picture is drawn that way because in the first shell, there should be only 2 electrons and 8 electrons in the second shell, However for the third shell, there are only 6 electrons left and so we say that there are 6 valence electrons in the 3rd shell.

And this, is the sulfide ion. 

and this, my friends is a Sulfide Ion. Sorry for the.... er, 'unique' drawing. I had a hard time drawing it using Windows Paint. BUT WOW, I made such an effort. Right, Mr Tan :P

*cough cough* but well, as show above; the configuration of the sulfide ion is (2.8.8) the third shell has GAINED 2 more electrons to achieve stability.

stability meaning that all respective shells have the perfect number of electrons it's supposed to contain and there's no extra or missing electrons.

 Because of this, the previous Sulfate atom becomes negatively charged and becomes a Sulfide ion.

The sulfide ion has gained 2 electrons and it now has a charge of -2.

#4

CHLORINE-35 ATOM AND CHLORINE-37 ATOM ARE ISOTOPES. 

Use these two examples to explain what isotopes are.

Firstly, isotopes are atoms of the same element with the same number of protons but different number of neutrons. 

Because of this, isotopes have the same proton number but different nucleon number.

As for Chlorine, it has 2 isotopes. Cl gas consists of 75% abundance of Cl-35 and the remaining 25% abundance is Cl-37. They have the same number of protons (17) however, their neutrons have different numbers. One has 18 (Cl-35), and the other; 20 (Cl-37). 

This is why they are isotopes. 

#5

SODIUM IS A METAL AND SULFUR IS A NON-METAL.

Why do we classify them this way? 

Metals in the periodic table lose electron(s) and become positively charged ions.

For Sodium, it loses one valence electron and hence it becomes a positively charged ion. In this way, they achieve a noble gas structure, therefore belonging to the 'Metals' group.

CATIONS are formed by atoms losing electrons. They are formed from metals and there is no change in name. 

As seen in the photo above, an atom becomes negatively charged when it gains electrons. Negatively charged electrons are called ANIONS.

 As for Sulfur (2.8.6), it needs 2 electrons to achieve a full shell. So Sulfur accepts 2 electrons and becomes a negatively charged ion. Hence, belonging to the 'Non-Metal' group. 

ANIONS are formed by atoms gaining electrons. They are formed from non-metals and they have a change of name.

First post!

Just to see how my blog will look like with a post (: will try to do some of the questions and everything tomorrow as it is already 12:38 in the morning!

And hey, I have to add photos and write as if this is my personal blog too, right?

So here I am at 12:39am in the morning.

HAHAAHHAHAHAHAHAHA!! 

And hey, I went the extra mile to google amazing photos of chemical reactions :P

and look at this video I found on Youtube!

SICKKKKKKKKKKKKKKKK

I didn't know Chemistry was this fun! 

http://youtu.be/1PJTq2xQiQ0