Chemistry questions help please! (1 Viewer)

[x.Exhaust.x]

Hey all. I need help with answering a few chemistry formulae questions and other questions. Here they are below, your help is greatly appreciated!

Formulae -

H2SO4 (aq) + 2NaO (aq) ---> Na2SO4 (aq) + 2H2O. The names of ea. element?
2Al2O3 (I) ---> 4Al (I) + 3O2 (g). The names of ea. element?
CaCO3 (s) + 2HCl (aq) ---> CaCl2 (aq) + H2O + CO2. The names of ea. element?

Write down each of the following chemical formulae and beside each write the total number of atoms in each formula.

CuSO4
KAl(SO4)2 . 12H2O
(NH4)2Cu(SO4) . H2O
Cu(NH3)4SO4 . H2O

Name of each compound -

Pbl2 -
Fe2(SO4)3 -
Al2(SO4)2 -

Questions -

1) Why can't noble gases form covalent compounds?

2) If an element has one elctron in its outer shell, is it a metal or a non-metal? Explain your answer.

3) If an element has seven electrons in its outer shell, is it a metal or a non-metal? Explain your answer.

4) What is special about elements that have eight electrons in their outer shell?

5) What experimental evidence is there to show that electron shells actually exist?

6) Draw electron diagram configurations to show how the following covalent compounds form:

a) Tetrachloromethane (CCl4)
b) Ammonia (NH3)
c) Carbon Disulfide (CS2)

7) How many electrons have been gained or lost by the following ions?:

a) Pb4+
b) Br-
c) Cr3+
d) Se2-

8) What is the difference between:

a) 2N and N2?

b) CO2 and C + O2

c) 2Cl2 and Cl2?

Thanks.

 

[Forbidden.]

Ah, the preliminary course, I'll try to help as much as I can.


Formulae -

Not all of these are compounds.

H₂SO₄ (aq) + 2NaO (aq) ---> Na₂SO₄ (aq) + 2H₂O.
Sulfuric Acid + Sodium Monoxide --> Sodium Sulfate + Water

2Al₂O₃ (I) ---> 4Al (I) + 3O₂ (g)
Aluminium Oxide ---> Aluminium + Oxygen

CaCO₃ (s) + 2HCl (aq) ---> CaCl₂ (aq) + H₂O + CO₂
Calcium Carbonate + Hydrochloric Acid ---> Calcium Chloride + Water + Carbon Dioxide


Write down each of the following chemical formulae and beside each write the total number of atoms in each formula.

They are chemical formulas on their own aren't they ?
Using KAl(SO₄)₂.12H₂O as an example:
To make it easier, first find the number of atoms in (SO₄)₂.
There are (1 + 4) x 2 (indicated by the 2 subscript), then you count the elements before it.
The water is added on as 12 x (2 + 1)

Therefore KAl(SO₄)₂.12H₂O has 1 + 1 + [(1 + 4) x 2] + 12 x (2 + 1) = 48 atoms

CuSO₄ = 6
KAl(SO₄)₂.12H₂O = 48
(NH₄)2Cu(SO₄).H₂O = 20
Cu(NH₃)₄SO₄.H₂O = 25


Name of each compound -

Pbl₂ - Lead(II) Iodide
Fe₂(SO₄)₃ - Iron(III) Sulphate
Al₂(SO₄)₂ -
I have doubts about this chemical formula.
The Aluminium ion has a charge of 3+ whereas the Sulphate ion has a charge of 2-, therefore 2Al³⁺ + 3SO₄^2- --> Al₂(SO₄)₃ Aluminium Sulphate (You cross multiply the charges of the ions to form the neutral compound)


Questions -

1) Why can't noble gases form covalent compounds?
Their outermost shell has a complete orbit of electrons which makes chemical reactions with it very difficult.

2) If an element has one electron in its outer shell, is it a metal or a non-metal? Explain your answer.
This free electron is able to move freely as electrical current and this fits with the property of metal which is a conductor of electricity


3) If an element has seven electrons in its outer shell, is it a metal or a non-metal? Explain your answer.
The seven electrons would be very difficult to remove let alone move around, so the atom finds it easier to accept electrons rather than pass them on like metals do.

4) What is special about elements that have eight electrons in their outer shell?
(Question 1 is a guide to this) They are inert because they cannot accept or reject electrons easily.

5) What experimental evidence is there to show that electron shells actually exist?

Image Below

A clue to this is what is known as ionisation energy.
Look back at your previous questions.
Looking at the trend of the graph above,
The low troughs show that there are only a few electrons in the orbit so they can be removed without much work.
The higher the peaks the more energy is required to remove electrons from that orbit, a high number such as seven electrons represent the peaks, showing it is harder to remove more electrons.
This pattern repeats with the number of orbitals.

6) Draw electron diagram configurations to show how the following covalent compounds form:

a) Tetrachloromethane (CCl₄)
b) Ammonia (NH₃)
c) Carbon Disulfide (CS₂)

7) How many electrons have been gained or lost by the following ions?:

An ion with a positive charge (⁺) has lost electrons, the more positive charges there are the more electrons lost.
An ion with a negative charge (^-) has gained electrons, the more negative charges there are the more electrons are gained

a) Pb⁴⁺ - 4 electrons lost
b) Br^- - 1 electron gained
c) Cr³⁺ - 3 electrons lost
d) Se^2- - 2 electrons gained

8) What is the difference between:

a) 2N and N₂?

b) CO₂ and C + O₂

c) 2Cl and Cl₂?


I'll get back to them later unless someone else is able to take my position to assist you.

 

[xiao1985]

6) see attachment

8)

a) 2N and N2?
2 nitrogen atoms (not necessarily covalently bonded) and nitrogen gas (covalently bonded)


b) CO2 and C + O2
Carbon dioxide and 1 carbon atm and oxygen


c) 2Cl and Cl2?
2 chlorine atom (not covalently bonded) and a chlorine gas molecule.

 

[x.Exhaust.x]

Thank you so much forbidden, xiao and again, lodgic .

 

[Forbidden.]

rolf, xiao1985 you answered those questions too :rofl:

Thank you so much forbidden, xiao and again, lodgic .

The more the merrier !

 

[x.Exhaust.x]

(NH₄)2Cu(SO₄).H₂O = 20

Hey forbidden, for that question you anwered, I got a different solution. For that one, I got a total of 24 atoms. Did I mistakenly calculate it wrong?

The last few questions I answered some of the questions myself. Please correct me if I'm wrong with your working out/solution to the answer. Thanks:

1) In the spaces between the particles that make up a sodium atom, would you expect to find any air? Explain.
No, because oxygen (O) is a separate element in comparison to sodium (Na). Therefore, you wouldn’t expect to find any air in the spaces between the particles.

2) The formulas N2 and O2 are used to represent nitrogen and oxygen respectively. What do these formulas indicate about these two elements?
<O</O
They indicate that both oxygen and nitrogen have two atoms of their own element.

3) What is the difference between a single and triple covalent bond, in terms of the number of electrons involved?
<O</O
Single and triple covalent have different chemical bonds. (Couldn’t answer the rest in terms of the number of electrons involved...)<O</O

Write down the answer to each formula:<O</O

1) Fe2(SO4)3 - <O</O
2) Ca3(PO4)2 – <O</O
3) Al(NO3)3 –<O</O
4) Ag3PO4 –<O</O
5) Fe(OH)3 – <O</O

Multiple choice questions:

1) The formulas of caesium chloride is CsCl, that of calcium chloride is CaCl2, and that of calcium sulphate is CaSO4. What is the formula of caesium sulphate?

A) CsSO4
B) Cs(SO4)2
C) Cs2SO4
D) 2CsSO4

2) The formula of aluminium sulphate is Al2(SO4)3. The number of atoms in molecule of the substance is

A) 9
B) 14
C) 15
D) 17

3) Which of the formula listed below contains the greatest amount of atoms?

A) K2Cr2O7
B) Al(OH)3
C) Ca3(PO4)2
D) MgSO4.2H2O

(The multiple choice answer in bold in every question are the ones I have answered myself. But I'm not 100% sure.)

Please leave all working out to every question as well if you don't mind. Thanks again.

 

[brenton1987]

1) In the spaces between the particles that make up a sodium atom, would you expect to find any air? Explain.

No. Having an oxygen atom within a sodium atom would cause it to either become unstable and decompose or change the sodium atom to an atom of potassium as the proton number increases.

2) The formulas N2 and O2 are used to represent nitrogen and oxygen respectively. What do these formulas indicate about these two elements?
<o></o>

Both nitrogen and oxygen are diatomic. They consist of two atoms of the respective element covalently bonded together.

3) What is the difference between a single and triple covalent bond, in terms of the number of electrons involved?
<o></o>

A single covalent bond involves a single electron from each atom being shared. It involves two electrons.
A triple covalent bond involves three electrons from each atom being shared. It involves six electrons.

Write down the answer to each formula:<o></o>
1) Fe2(SO4)3 - <o></o>
2) Ca3(PO4)2 – <o></o>
3) Al(NO3)3 –<o></o>
4) Ag3PO4 –<o></o>
5) Fe(OH)3 – <o></o>

1 Iron (III) Sulfate
2 Calcium Phosphate
3 Aluminium Nitrate
4 Silver (I) Phosphate
5 Iron (III) Hydroxide

1) The formulas of caesium chloride is CsCl, that of calcium chloride is CaCl2, and that of calcium sulphate is CaSO4. What is the formula of caesium sulphate?
A) CsSO4
B) Cs(SO4)2
C) Cs2SO4
D) 2CsSO4

2) The formula of aluminium sulphate is Al2(SO4)3. The number of atoms in molecule of the substance is
A) 9
B) 14
C) 15
D) 17

3) Which of the formula listed below contains the greatest amount of atoms?
A) K2Cr2O7
B) Al(OH)3
C) Ca3(PO4)2
D) MgSO4.2H2O

1 Cs₂SO₄
2 17
3 Ca₃(PO₄)₂

 

[WantToDoBetter]

Look, i love chem, i really do, but the only way u'll get this stuff down pat Razizi is if you do your homework yourself. It's like your posting your whole work sheet. If your seriously stuck with a question then post as you did with your second post which was a lagit attempt. In the end it's your learning but speaking from experience, you need to know this general prelim stuff to go anywhere in the HSC course. I hope you will consider this, seriously.
Cheers.

 

[x.Exhaust.x]

Look, i love chem, i really do, but the only way u'll get this stuff down pat Razizi is if you do your homework yourself. It's like your posting your whole work sheet. If your seriously stuck with a question then post as you did with your second post which was a lagit attempt. In the end it's your learning but speaking from experience, you need to know this general prelim stuff to go anywhere in the HSC course. I hope you will consider this, seriously.
Cheers.

Alright, first off, you can keep your affectionate love to chemistry to yourself, thanks Secondly it isn't my whole worksheet. I received so many chemistry sheets from my chemistry tutor and with the questions I posted, I put a number for each question, as they were the questions I wasn't sure of. But I agree with you, I shouldn't be posting a bunch of questions for you guys to complete, but say 1-5 questions would probably do. For you, it may look like I'm not doing any work at all and posting the questions up so I can just look at them and copy them down for fun. But instead of waiting for my chemistry tutor to arrive after the holidays, I'd like to get these questions over and done with, so when my tutor arrives, we would've already went over the work faster and we can continue onto the next chapter. I think 'keen' is the best term for the sentence before.

And thanks for the advice of knowing the general preliminary course to continue on with the chemistry HSC course, which, isn't it obvious? lol. But for my last point, if I continue to post the questions up that I DID NOT UNDERSTAND at all, would it be a harm for others to answer it if they'd wish to?

1. They don't have to do it if they don't wish to, and if they do, they are very kind enough to help, and the best I can do is thank them, or send a bunch of chocolates (won't be happening lmao).
2. I've been a member in boredofstudies since last year, and this is a student community with high school students and university students helping each other and posting questions up
3. There aren't any restrictions in posting questions?

But as I said, this will probably be the last time I will post up a bunch of questions (excluding HSC), and I will consider your words WantToDoBetter. Your name explains best of why I posted the questions up so early, instead of going through it with the chemistry tutor.

Edited:

Thanks the 3rd time lodgic <3 lol not in a real way haha, and of course brenton =].

 

[WantToDoBetter]

Alright, first off, you can keep your affectionate love to chemistry to yourself, thanks Secondly it isn't my whole worksheet. I received so many chemistry sheets from my chemistry tutor and with the questions I posted, I put a number for each question, as they were the questions I wasn't sure of. But I agree with you, I shouldn't be posting a bunch of questions for you guys to complete, but say 1-5 questions would probably do. For you, it may look like I'm not doing any work at all and posting the questions up so I can just look at them and copy them down for fun. But instead of waiting for my chemistry tutor to arrive after the holidays, I'd like to get these questions over and done with, so when my tutor arrives, we would've already went over the work faster and we can continue onto the next chapter. I think 'keen' is the best term for the sentence before.

And thanks for the advice of knowing the general preliminary course to continue on with the chemistry HSC course, which, isn't it obvious? lol. But for my last point, if I continue to post the questions up that I DID NOT UNDERSTAND at all, would it be a harm for others to answer it if they'd wish to?

1. They don't have to do it if they don't wish to, and if they do, they are very kind enough to help, and the best I can do is thank them, or send a bunch of chocolates (won't be happening lmao).
2. I've been a member in boredofstudies since last year, and this is a student community with high school students and university students helping each other and posting questions up
3. There aren't any restrictions in posting questions?

But as I said, this will probably be the last time I will post up a bunch of questions (excluding HSC), and I will consider your words WantToDoBetter. Your name explains best of why I posted the questions up so early, instead of going through it with the chemistry tutor.

Edited:

Thanks the 3rd time lodgic <3 lol not in a real way haha, and of course brenton =].

NEVER!!!! I LOVE CHEM!
Anyway, you seemed to not want to even try just by the amount of work you put up in you first post for these kind people to answer. Use a thread like this as a secondary resource after you urself has exhausted other reasources. When i was stuck, i spent hours on google looking for different practice questions or answers to my questions.

1. 2. People help you because they are kind enough to, i wasn't discouraging others not to answer your questions as you seem to think i am.
3. Nor was i placing restictions on the amount you or anyone else can post, again you seem to get that impression when it clearly isn't there.

What i did write was that it seemed to ME as though you were just being lazy. By posting what looked like a whole work sheet i was made to believe that you were after a "quick fix" but i wasn't sure of the circumstances so i only offered FRIENDLY advice.

If you find some advice that i feel compelled to give useless, due to it being a blantant fact to yourself, then discard it and leave it at that, sardonic comments transform light friendly comments into unessicary and unwanted scorn and bicering.

It is great to want to do better. I joined BoS for two reasons, to help people and offer advice and to receive help.

I wish you the best of luck and if you read my post as an indifferent "stab" at you then you were mistaken. If that was your perception i apologise.
If you post anything else i will view it with sincerity and always help if i can.
Again best of luck.
Cheers.

 

[x.Exhaust.x]

I wish you the best of luck and if you read my post as an indifferent "stab" at you then you were mistaken. If that was your perception i apologise.
If you post anything else i will view it with sincerity and always help if i can.
Again best of luck.
Cheers.

No need to apologise. But thanks for replying, as now I more so understand what you said. And thanks for offering your help. Appreciate it.

All the best in your HSC. Good luck.