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re: HSC Chemistry Marathon Archive 99% sure they do. It's only pressure and volume that are affected by only gases, right? I'd like a fourth opinion on this though.

no...

lol chem and easy marking don't go together.

re: HSC Chemistry Marathon Archive You don't have to. As long as you have one detailed example, you should get the marks. The marking guidelines for 3-4 (the question I have is only worth 4 marks) marks were: - names a recent development of a named biopolymer - states desirable properties of...

re: HSC Chemistry Marathon Archive what? i dont think thats right?

If one mole of pentanol is combusted, 2800kJ of heat is generated. How many moles of pentanol should be combusted to generate 108kJ of heat? 1mol ---- 2800kJ xmol ---- 108kJ x = 108kJ . 1mol / 2800kJ = 0.03857...mol Then just use m = n x M, and you should get D.

When writing equations, I put Cl with a dot. Same thing when writing it in a sentence " the Cl(dot) radical" [or "the chlorine radical"] Same thing for ions. In equations, H+ and when writing it in a sentence "H+ ions" or "hydrogen ions"

re: HSC Chemistry Marathon Archive I used the tests for BOD and DO for this. Is that wrong...?

No, it's not because of that.. NH4Cl disassociates in water: NH4Cl --> NH4+ + Cl- NH4+ reacts with water to form an excess hydronium ions NH4+ + H2O --> NH3 + H3O+ It is the presence of the hydronium ion that lowers the pH, and makes the solution acidic. Hence, NH4Cl is an acidic salt. As for...

There's another way to do it. 1. Find the percentage of sulfate - this comes to 16.89...% 2. For percentage of sulfur: ( molar mass of sulfur / molar mass of sulfate ) x percentage of sulfate (32.07 / 96.07) x 16.89... = 5.64%

re: HSC Chemistry Marathon Archive Explain why models are useful in chemistry. [2] lol guess I really do know nothing from module 3.

re: HSC Chemistry Marathon Archive 2)Describe how to quantitatively measure the amounts of nitrates and phosphates Is it by measuring dissolved oxygen and biochemical oxygen demand? Or is that for eutrophication? Or am I completely off?

re: HSC Chemistry Marathon Archive why can't there be more calculation questions :/

re: HSC Chemistry Marathon Archive Haha, sorry. It was only worth 2 marks. But the sample answer says "provides surface for particles to collide". So you probably don't have to include "speeds up rate of reaction"

Yes, it is exactly that.

Exoothermic: N2 + 3H2 --> 2NH3 Energy is required to break the bonds between the N atoms in N2, and the H atoms in H2. Therefore, energy is absorbed. When the bonds in NH3 form, energy is released. For this reaction to be exothermic, heat has to be released overall. So, the amount of heat...

re: HSC Chemistry Marathon Archive This isn't right, but how did you get the bolded part? :s If you want to see the solution, scroll up :D

re: HSC Chemistry Marathon Archive I don't think you should say that either. Also, this sounds incomplete: "Concentrated is used when an acid has a high concentration". Okay, but a high concentration of what? The term 'concentration' refers to the concentration of solute in a solution. If an...

When bonds are broken, energy is absorbed. When bonds are made, energy is released. Whether a reaction is endothermic or ectothermic depends on the amount of energy required to break bonds, and the amount of energy released when bonds are formed. Not the other way around.

re: HSC Chemistry Marathon Archive What is the difference between the terms 'strong' and 'concentrated' when referring to acids?