Prelim Chem Thread (2 Viewers)

[1008]

Need help with chemical equations:

1. heating potassium chlorate, KCLO3, to form solid potassium chloride and oxygen gas
2. reacting aluminium with aqueous hydrochloric acid, HCL, to produce aqueous aluminium chlirode and hydrogen gas
3. Burning Hydrogen sulfide gas in oxygen to form gaseous sulfur dioxide and gaseous water
4. CO+O2--->C02. This took me a while to solve properly (I solved it by asking someone for their answers and I don't really want to do that)
5. Na+H2O--->NaOH+H2. For some reason, when I am adding all these numbers and trying to balance the chemical equation, I am still not able to balance it and I've spent a while doing that
6.HCL+AL--->AlCl3+H2. Same reason as 5
7. Nitirc acid+sodium hydroxide
8. Sulphuric acid+magnesium
9. Hydrochloric acid+magnesium oxide
11. Sulphuric acid+calcium oxide
12. Hydrochloric acid+magnesium carbonate
13. Nitric acid+aluminium bicarbonate

1. 2KClO3 (s) --> 2KCl (s) + 3O2 (g)
2. 2Al(s)+ 6HCl(aq) --> 2AlCl3(aq) + 3H2(g)
3. H2S(g) + O2(g) --> SO2(g) + H2O(g)
4. Done by yourself

 

[eyeseeyou]

1. 2KClO3 (s) --> 2KCl (s) + 3O2 (g)
2. 2Al(s)+ 6HCl(aq) --> 2AlCl3(aq) + 3H2(g)
3. H2S(g) + O2(g) --> SO2(g) + H2O(g)
4. Done by yourself

4 was CO+02-->CO2

LHS=3 Oxygen atoms and 1 carbon atom
RHS=1 carbon atom and 2 oxygen atoms

 

[eyeseeyou]

What are the main things I need to remeber in water before a water test?

 

[eyeseeyou]

I would probably answer your questions by saying "by inspection".

This literally shows you have no pure understanding of the sciences

 

[eyeseeyou]

2. Pure substances have a constant, definite composition. Why? It cannot be separated into simpler substances by physical means. Why?
3. If there is an imbalance in chemical equation, why would we need to add extra numbers in order to balance it?
4. Why is sodium+hydrochloric acidSodium chrloride+hydrogen gas
5. Why does delta H represent a change in heat energy (enthalpy)?
6. Why does delta H < 0 represent heat energy released (exothermic)?
7. Why does delta H>0 represent heat energy absorbed (endothermic)?
8. Why are elements considered the simplest substances which cannot be broken down into further physical and chemical means?
9. Why are elements made up of only one type of atom?
10. Why are all known elements listed on the periodic table?

I'll do 1 at a time to make your life easier Integrand

 

[InteGrand]

I'll do 1 at a time to make your life easier Integrand

But I have ''no pure understanding of the sciences'', so it makes no difference for me.

 

[eyeseeyou]

But I have ''no pure understanding of the sciences'', so it makes no difference for me.

Well...are you an expert in the field of chemistry (I know you're an expert in maths and physics)?

 

[eyeseeyou]

Can someone give me tips on what I should write for these following dotpoints?

1. Living organisms make compounds which are important sources of energy

outline the role of photosynthesis in transforming light energy to chemical energy and recall the raw materials for this process

outline the role of the production of high energy carbohydrates from carbon dioxide as the important step in the stabilisation of the sun’s energy in a form that can be used by animals as well as plants

identify the photosynthetic origins of the chemical energy in coal, petroleum and natural gas

process and present information from secondary sources on the range of compounds found in either coal, petroleum or natural gas and on the location of deposits of the selected fossil fuel in Australia

 

[eyeseeyou]

There is so much useless off-syllabus crap being asked on here

It benefits your understanding and hence you won't have to memorise as much

 

[BlueGas]

Can someone give me tips on what I should write for these following dotpoints?

1. Living organisms make compounds which are important sources of energy

outline the role of photosynthesis in transforming light energy to chemical energy and recall the raw materials for this process

outline the role of the production of high energy carbohydrates from carbon dioxide as the important step in the stabilisation of the sun’s energy in a form that can be used by animals as well as plants

identify the photosynthetic origins of the chemical energy in coal, petroleum and natural gas

process and present information from secondary sources on the range of compounds found in either coal, petroleum or natural gas and on the location of deposits of the selected fossil fuel in Australia

Don't wanna go into too much detail for that one but basically light reactions are carried out in the thylakoid membrane of the chloroplast where light energy is converted to chemical energy, after the light reactions occur the Calvin Cycle (also known as the Kreb's cycle) takes place, forming Glyceraldehyde 3-phosphate, which can then undergo gluconeogensis to form glucose. The raw materials for photosynthesis are carbon dioxide and water.

 

[BlueGas]

There are two types of chlorophyll, a and b, they absorb light at specific ranges and the energy from this light undergo the light reactions. In order to understand the light reactions you gotta go awwaaaaay from the syllabus to know what happens though.

 

[eyeseeyou]

Cheers Bluegas

 

[drsabz101]

What is the amount of ethanol in 750ml of wine, if it is given that ethanol has a content of 12% w/v.


HOW do you solve this? Could someone outline the solution step by step. Thanks! I am still confused with moles

 

[ThreeSciences]

What is the amount of ethanol in 750ml of wine, if it is given that ethanol has a content of 12% w/v.


HOW do you solve this? Could someone outline the solution step by step. Thanks! I am still confused with moles

Weight/volume (w/v) percentage is a measure of the concentration of a solution:

• 12% w/v = 12g/100mL
• Divide both sides by 100 (to get g/mL) = 0.12g/mL
• Multiply both sides by 750 to get 750mL = 90g/750mL

So the answer should be 90g.

 

[eyeseeyou]

2. Pure substances have a constant, definite composition. Why? It cannot be separated into simpler substances by physical means. Why?
3. If there is an imbalance in chemical equation, why would we need to add extra numbers in order to balance it?
4. Why is sodium+hydrochloric acidSodium chrloride+hydrogen gas
5. Why does delta H represent a change in heat energy (enthalpy)?
6. Why does delta H < 0 represent heat energy released (exothermic)?
7. Why does delta H>0 represent heat energy absorbed (endothermic)?
8. Why are elements considered the simplest substances which cannot be broken down into further physical and chemical means?
9. Why are elements made up of only one type of atom?
10. Why are all known elements listed on the periodic table?

Someone please help me

 

[BlueGas]

Someone please help me

Almost all your questions are useless, no offence.

 

[eyeseeyou]

Almost all your questions are useless, no offence.

I'm asking 10 questions at once. Also its for the benefit of understanding (although it's not going to be asked in exams)

 

[BlueGas]

I'm asking 10 questions at once. Also its for the benefit of understanding (although it's not going to be asked in exams)

They never will be asked in exams. Just look at your last question... why would you want to ask that?

 

[eyeseeyou]

1.When water boils and evaporates, what happens to the particles?
2. When water is heated and boiled, do the H2O molecules ever break up? Explain
3. Use diagrams to model the arrangement and movement of particles in cold water and boiling water
4. Describe the tests you used to identify the oxygen and hydrogen produced

 

[eyeseeyou]

@Bluegas read this: http://www.keystoneeducation.com.au...-can-do-to-ace-the-hsc-with-almost-zero-study
https://www.matrix.edu.au/how-i-topped-physics-at-fort-street-high-wasim-awal/

hopefully you'll understnad why I ask these questions