DeanK2

A thorough revision of your notes will help. It is certainly something that needs to be practiced as there will usually be one to three transformations per problem.

There is some use for both. By using sulfuric acid to liberate bromine from KBR would be the quickest, cheapest and least dangerous method. The oxidation stops when bromine is produced. If you are intersested, this is a two part reaction: 1.) KBr + H2SO4 -------> KHSO4 + HBr (sulfuric acid acts as an acid) 2.) 2HBr + H2SO4 ------> Br2 + SO2 + 2H2O (sulfuric acid acts as an oxidising agent) Excess acid must be used Hydrogen iodide proceed to further react with sulfuric acid, so Iodine is completely obtained from reacting with sulfuric acid, but other reactions take place that produce substances that take more time to safely remove (yet all Iodine will be liberated). 1.)KI + H2SO4 ---------> KHSO4 + HI 2.)2HI + H2SO4 -------> I2 + SO2 + 2H2O 3.)6HI + H2SO4 -------> 3I2 + S + 4H2O 4.)8HI + H2SO4 -------> 4I2 + H2S + 4H2O To obtain Iodine, a simple redox reaction can be performed. Simply add the KI with chlorine. 2KI + Cl2 --------> 2KCl + I2 Best of luck. However, these are extremely harmful and potentially problematic chemicals.

What is the answer? Well, a set of axioms must be established. I think everyone reading can agree that Axiom 1: 0 = 1/∞ Therefore 0/0 identical to (1/∞)/(1/∞). Using (x/y)/(p/m)=(x/y)x(m/p), it must be true that 0/0 is the same as ∞/∞. This is very similar to the first question. Why isn't ∞/∞ simply one? Well, ∞ = ∞+∞. Following on, if ∞/∞ was 1, then what is (∞+∞)/∞? Splitting the fraction, it becomes apparent that (∞+∞)/∞ = (∞/∞)+(∞/∞). 1 can never be equal to 2.

Q=cmΔT can also be written as Q=(m)©(ΔT) Q is the heat change (kJ per mol) m is the mass of water or solvent (g) c is the specific heat capacity of water (4.18 J per g per K) ΔT is the overakk temperature change in K If a work example is needed simply email and will send unique solution

All the questions require short steps and I hope you will figure them out. However, for each question a small aid is usually beneficial. I have completed each question, so if you post your results after, it would maybe be helpful. To really do you justice, I have outlined how to complete each question with no exact answers. [hide]1.) This really is just a unit conversion question. 2.) O2 has a density value given. Simply multiply (by 5), giving the mass in grams of the oxygen evolved (specified in question). Use moles of O2 =(mass (g)/atomic mass). Multiply by 2 for the moles of sodium nitrate. Following this, multiply by the atomic mass of sodium nitrate (85). This is 78.4% of the value for the grams of sodium nitrate originally. To obtain the theoretically minimum mass of sodium nitrate, simply divide by 78.4 and multiply by 100. Your answer will be close to 100 grams, yet to help you, I have not given an exact answer. 3.) The question requires knowledge of an empiracle formula - assuming you are aware of an empiracle formula (the simplest ratio of elements in a compund), it would be quite a good question. As a greater mass of iron (III) oxide than cementite has been created it is logical that this came from oygen in the air. Unfortunately, the ratio of iron (III) oxide: carbon dioxide is not given. An equation like this: (m)O2 + (n)X --> (o)FE2O3 + (p)CO2, were m,n,o,p are constants representing the moles , cannot be set up. This means the empiracle CANNOT be found with this little information. 4.) See question 2 and 5, as both of these methods are needed. This question contains irrelevant information - such as comparison with copper and so forth. However, the question does allow you to work backwards and find the moles of each substance in question. 5.) This is just a percentage purity problem. Work backwards from sulfuric acid, in simple steps. I.E: moles=(mass (g)/relative atomic mass) = (75000/98) = 765.306. This is the same amount of moles of SO3 in the reaction SO3 + H2O --> H2SO4. The moles of SO3 can be used to work backwards. However, do not be tempted to times this number by 2, just because 2SO2 + O2 --> 2 SO3 has a 2 in front of SO3, and the equation to make sulfuric acid does not. Remember that the equations only show the ratio of each molecule or substance with respect to another, while the moles represent an actual amount of the substance. Once a value for the moles of Sulfur has been found, multiply by 32, its atomic mass. Then remember to divide by 98 and multiply by 100.[/hide]