Some Study Questions (1 Viewer)

[jesst]

Here are some study questions to see if you've covered the basics. I guess if you can anwer all of them you're well on your way. I'll post up more later if you guys want.

1. What is a strong acid?
2. What is a weak acid?
3. What is an indicator?
4. What is Litmus?
5. What other indicators could be used to indicate the environment pH?
6. The oxides of what three elements cause acid rain?
7. What period in history corresponds to the increase in acid oxides in the atmosphere?
8. What activity became significant in this time to cause acid rain?
9. The combustion of PVC plastics also contributes to acid rain, how does this cause acid rain?
10. What causes localised areas to have major problem with acid rain?
11. List five environmental consequences of acid rain
12. What three acidic oxides are naturally occurring in our atmosphere? and
13. What period in history corresponds to the increase in natural occurring acidic oxides in the atmosphere?
14. What was it about the industrial revolution that caused the increases in the amounts of acidic oxides in the atmosphere?
15. What do these acidic oxides react with to form acidic rain?
16. What are the natural sources of sulfur dioxide in the air?
17. How does the burning of PVC contribute to acidic rain?
18. Why can’t the pH of soil be tested directly using universal indicator?
19. Why is Barium Sulfate used in measuring the pH of soil?
20. Why can’t other white compounds such as powdered sodium carbonate be used to absorb the water from the soil for pHtesting?
21. What is Le Châtelier's principle?
22. What factors affect the equilibrium of a system?
23. How is a gaseous equilibrium system affected by changes in pressure?
24. How are equilibrium systems affected by temperature?
25. How does the addition of product or reactant to a system that has already reached equilibrium affect the position of the equilibrium?
26. What affect does the addition of a catalyst have on an equilibrium system?
27. What compound forms when carbon dioxide dissolves in water?
28. What causes the carbon dioxide equilibrium system to shift from the left to the right?
29. Why does this shift occur according to Le Chatelier’s principle?
30. Why does the release of pressure on this equilibrium system cause it shift back towards the left hand side?

 

[steve_ell]

lol i would mind some answers posted .lol... as im in big trouble for my chem hsc

 

[Xayma]

Fine Ill answer them.

1. A strong acid is one that ionises completly.
2. A weak acid does not ionise completly.
3. An indicator is a material that changes colour based on the pH of a solution.
4. Litmus is an indicator, derived from algae (I think its algae not 100%)
5. Tons of them, if you dont want the standard indicators like Methyl Orange, things like Hibisicus flowers.
6. Carbon, Nitrogen, Sulfur
7. Industiral Revolution to the present
8. Large scale combustion of coal products often which contained large amounts of sulfur.
9. PVC when burnt releases Hydrogen Chloride, which forms Hydrochloric Acid in rain.
10. No idea on this question based on the wording, but things acid rain would cause trouble to is water sources without an adequate buffer, limestone.
12. CO₂, NO₂, SO₂, SO₃
13. See 7
14. See 8
15. Water
16. Volcanoes, hot springs.
17. See 9
18. It cant be seen
19. To provide a white background so that when the indicator comes up it has a contrasting colour
20. They change the pH
21. A system at equilibrium will change direction in order to minimise a disturbance
etc etc

 

[~*HSC 4 life*~]

22. What factors affect the equilibrium of a system?

-temperature (is the fwd reaction exo or endothermic? this will help you find out which way the equil position lies due to LCP)

23. How is a gaseous equilibrium system affected by changes in pressure?

an increase in pressure would by LCP cause an equil to shift to the side with fewer gaseous moles
an decrease in presuure--> more gaseous moles

24. How are equilibrium systems affected by temperature?

an increase in temp would favour the endothermic reaction
a decrease in temp would favour the exo

25. How does the addition of product or reactant to a system that has already reached equilibrium affect the position of the equilibrium?

adding a product/reaction is like increasing its conc, therefore if u add a product, it would shift to LHS (reactant side) and vice versa

26. What affect does the addition of a catalyst have on an equilibrium system?
no effect on eqiul pisition

27. What compound forms when carbon dioxide dissolves in water?

carbonic acid

CO2 + H20 ---> H2CO3
28. What causes the carbon dioxide equilibrium system to shift from the left to the right?

this is COS equil

CO2 g--> CO2 (aq)

CO2 (aq) + H+ ---> HCO3-

HC03- + H+ --> H2CO3 (aq)

to shift this right we can, add an acid...increase temp...and increase pressure i think

29. Why does this shift occur according to Le Chatelier’s principle?

it will shift to minimise any burden you place on it

 

[Xayma]

22. You only mentioned one of them, metion all of them, concentration, temperature, pressure (if a gas is involved).

28. An increase in temperature will shift it to the left.

CO_2(g)<----->CO_2(aq) is an exothermic process, where as the other ones are negligble compared to it.

 

[Plebeian]

10. No idea on this question based on the wording, but things acid rain would cause trouble to is water sources without an adequate buffer, limestone.

Possibly areas which contain power-plants, sulfide ore smelters etc. or regions with high sulfur-content coal would be more prone to acid rain.

 

[~*HSC 4 life*~]

if it is endothermic and you increase the temperature, it shifts right.

 

[Xayma]

Exothermic now fixed.

Gaseous states have a higher energy then aqueous states. So an introduction of heat pushes them to a higher energy to absorb the heat.

 

[~*HSC 4 life*~]

i'm a bit confused...ah?

can anyone elaborate on this?

i thought dissolution of gases was an endothermic process

 

[~*HSC 4 life*~]

Exothermic now fixed.

Gaseous states have a higher energy then aqueous states. So an introduction of heat pushes them to a higher energy to absorb the heat.

oh ok

but if gases are at a higher energy level, then if you add energy like heat, wouldn't it wanna minimise it, hence it would go to (aq)?

 

[Xayma]

No because you are trying to minimise change. Having the atoms move more results in less radiation released.

Similar reason why most solids become more soluble as temperature rises as generally aqueous states have more energy then solid states.

 

[t-i-m-m-y]

31. What is the probability of passing HSC chem?