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Question: discuss the need for alternative for the petrochemical industry The petrochemical has a variety of social and environmental problems asociated with it, the main ones being; -The petrolium of the world is not infinite and will run out in the next 30 years according to many. -When...

Polyvinyl chloride has excelent electrical insulation properites and is generally very tough and flexible, however it is not weather resistant and as such should not be exposed to direct sunlight. These properties make it perfect for use in electrical insulation in the home. Polystyrene is an...

It's there now^^. Post up some new quesitons please. Question: Contrast the processes that produce low-density polyethylene and high density polyethylene.

The current value that the data sheet gives is C = 4.18 * 10^3 J kg^-1 K^-1 working from there; C = 4.18 *10^3 J kg^-1 K^-1 C = 4.18 *10^3 J 1000g^-1 K^-1 C = 4.180 J g^-1 K^-1 Which is the value that you are probally mreo familiar with. If you want to use this value you have to start...

It is vital the you include equations. If there is an equation that can be included you will not get full marks unless you do, a detailed explaination is not enough, if are not sure that the equation is right write it in the margin that way you shouldn't lose marks if it is wrong...

When you say calculate the oxidation state what exactly do you mean? Loss of an electron increaces the oxidation state gain of an electron reduces the oxidation state. For the rust equation I will be using the overall equation: 4Fe(OH)2 + O2 ---> 2(Fe2O3.H2O) +2H2O or 4Fe(OH)2 + O2 --->...

If you are going to calculate for a back titration it helps to know how one is performed. The steps involved are actually quite simple: 1- React the solution being measured with an excess of as appropriate standard (generally NaOH for an acid and HCl for a base) and leave for a time to allow...

Re: what raw marks you need for band 5/6 lol i can't really argue with that

I don't see how they could have possibally got A for that question, their reasoning is quite flawed: "Filtration (S) cannot be used to separate dissolved substances and a separating funnel (R) is used to separate liquids" However to find the total dissolved solid you must first remove the...

That is the best explaination of the Ph of salts that I have ever heared, it makes so much more sense that way than the way that my textbook tries to explain it.

Re: what raw marks you need for band 5/6 Hmm ok fair enough. If it was so easy why were sp many ppl complaining about it? Maybe they were people who just can't take that they didn't do that well, or that their students didn't do that well. I hope it's much harder than last years, since...

I would say that it was important to know that copper is a trace element and as such very small concentrations (a few ppm) of it in waterways is important and that anything larger than this can have dangerous consequences Question: Discuss the effectiveness of AAS in pollution control and...

Re: what raw marks you need for band 5/6 I have heard that it was very hard and included things that were only just in the syllabus, the head teacher of science at my school said it was very hard. The main reason that it was considered hard was because it included high mark questions on...

Re: what raw marks you need for band 5/6 They can and will give you marks for anthing you can see, my chem teacher told me that if you are not sure about and equation write it in the margin, that way if its right you will get marks for it and if you are not you wont lose marks.

Molar heat of combustion is the heat liberated when one mole of a substance if combusted assuming no heat loss and complete combustion. The method that real labs use to determine the molar heat of combustion is called a bombcolorimeter: -a known amount of the substance and the oxygen that is...

Re: what raw marks you need for band 5/6 You can ask for writing booklets which you can attach and direct them towards in your answer, I usually don't follow the lines, I write down past where the lines end the down the margin first.

We don't have to know about AAS calibration curves, the syllabus says: "describe the use of AAS in detecting concentrations of metal ions in solutions and assess its imact on scientific understanding of the effects of trace elelments" I dont see how they could possibally get calibration...

Re: what raw marks you need for band 5/6 This question always seems to come up before exams and the answer is always the same, it depends on the test. One thing i can almost gurantee is that the cut off will be higher this year than last year since so many people complained about how hard...

You need the basic components which are -electrolytes -electrodes usually either the metals which are in the solution or inert metals such as graphite or platimun -a salt bridge and external circut for the electrons to flow Question:Why is the hole in the ozone layer concentrated over the...

some equations for the ethanol ect. one fermentation C6H12O6(aq) ---> 2CH3CH2OH(aq) + 2CO2(g) i think the ethanol to ethyl butanoate is: CH3CH2OH(ethanol) + CH3CH3CH2COOH(butanoic acid) ---> CH3COOCH2CH3CH3CH3(ethyl butanoate) + H2O