Chemistry

Hey, I was learning about the enthalpy of hydration today and it went *whoosh* right over my head. Have a look at this paragraph from my textbook Erm okay, I have several questions Why is energy released when a bond is formed? How does the attraction of water molecules to ions release energy? Is hydration where water molecules break down a lattice by attraction and then water molecules end up surrounding a single ion OR is this solvation OR a special water case of solvation? Whats the difference between the enthalpy of solvation, the enthalpy of solution and the enthalpy of hydration? The paragraph says "Part of the energy is released...", so ther…

I urgently need help on a topic of discussion with a close friend, who feels he has been set up by the CPS concerning some residue of a controlled drug. The CPS are claiming that very small traces of narcotine, monactylmorphine and morphine were found on a surface, and because: 1. monactylmorphine is a breakdown product of diamorphine (heroin), 2. It in turn breaks down into morphine, 3. monactylmorphine is commonly seen along with narcotine in illicit drugs, 4. Diamorphine residue would break down (by itself) into monactylmorphine and morphine, over a period of 10 years or more, it is a proof that the traces found were once diamorphine (heroin). …

Below is a quote from wikipedia refering to the factors that increase the rates of chemical reactions: "Temperature: The kinetic energy of particles follows the Maxwell-Boltzmann distribution. An increase in temperature not only increases the average speed of the reactant particles and the number of collisions, but also the fraction of particles having kinetic energy higher than the activation energy. Thus, the effective collision frequency increases" So, the above quote states there are 2 reasons why temp increases rate of reaction. 1) temp increases the average speed of particles. 2)increases the kinetic energy of particles. I'm a little confused at this di…

Hi everyone, I am studying by myself at home, and this summer I am sitting my gcse sciences. I have to do coursework at home, and I have no idea what to do - any ideas anyone? I have no science equipment, I am prepared to buy some but I guess there is a limit to what I can buy? Anyone any good ideas for a good experiment which would give me the potential to gain top marks that I could do at home? thanks in advance everyone! Marc

Hi everyone, In relation to another post about reaction rates, please could someone answer if it is conventional in chemistry to use significance tests like chi-squared? For example, would it be used in something like a rates of reaction test? If reaction rate is supposed to double as you increase temp by 10°C but you find the increase is 1.8 rather than 2 - could you use chi-squared to see if this is a significant relationship. What would the scientific community think of using suck techniques to test significance? thanks as always

Hi everyone, So when sodium thiosulphate & hydrochloric acid react what is happening in terms of bonds breaking/being made to creat the new products? 1)In the word formula we write: Sodium thiosulphate + hydrochloric acid → sulphur + sulphur dioxide +chloride which is fine but 2NaCl is Sodium Chloride is n't it? So why do we omitt the Sodium in the wording of the products and just call it chloride? Also what happens to the hydrogen of the hydrochloric acid? It's part of the reactants but it isn't a product? Na2S2O3(aq) + 2HCl(aq) → S(s) + SO2(g) + 2NaCl(aq) 2Na2S2O3(aq) + 4HCl(aq) → S(s) + 3SO2(g) + 4NaCl(aq) But back to my original …

Hi all, I've got a few questions about collision theory....... 1)re: activation energy, do some particles collide but because they have an insufficient amount of energy they do not react (would these be known as ineffective collisions as opposed to effective collisions)? 2)what exactly is colliding? Electrons or full atoms? thanks very much!

Hi everyone, I've just done a science experiment - a fairly simple one testing rates of reaction using sodium thiosulphate (0.1 concentration 50ml) & hydrochloric acid (also 0.1 concentration 50ml). I wish I'd asked my tutor at the time but I didn't, and now I need to know why I decided to use a 0.1 concentration of each liquid and why I decided to use 50mls vloume of each liquid. Can anyone think of any scientific justifications? thanks for your help in advance!

During my homework I came across a question I am not sure how to answer: In experiment 1 there is: 2cm strip of Magnesium An Acid in a beaker In Experiment 2 there is: 4cm strip of Magnesium An acid with twice the concentration of the acid in experiment 1 The acid has the same volume Now in these experiments would the Magnesium react faster in experiment 1 or 2. And Why? Thanks in advance!

hello, ive got an analytical chemistry project to do. i have to choose a topic about bioprospecting in the middle east and effectively carry out the experiment and it has to be of valuable use. i have no idea plz send me ur suggestions thx

What substance(salt) facilitates the self-ionization of water when it dissolves in water? What about ammonium chloride? Does it accomplish the job above? Which reaction for it has a greater dissociation constant? the reaction of NH4+ with water or the reaction of it with hydroxide ion?

I have just recieved my grade on my enthalpy test (78) and have a few questions in which my teacher was unable to answer to my understanding. 1. In exothermic reactions, the products contain more heat than do the reactans. Sometimes True, Never True, or Always True? I put AT because wouldn't the products gain heat from the reactant? 2. Here is a multiple choice question in which I also missed: A limiting Reactant: a. may be heat but only in an exothermic reaction. b. may be heat but only in an endothermic reaction c. does not involve the heat change at all d. both a and b are correct e. none of the above. The answer for 2 is "B" but why?

I'm writing up a critique for my chemistry class and at the end paragraph, I have to conclude with my point of view (early in the paper, I talked about the pros of the article and cons of the article by using evidences from the paper). What type of things should I address in the conclusion? I don't want to just bluntly says, "I agree(disagree) with...." and just end it there. What kind of things do you guys normally address at the end of critique? I'm putting this under chemistry because it's from chemistry class and deals with radioactive burial under the sea.

Hi I have a weird question that is from a biology lab but has to do with chemistry. We were testing the effect of different pH on bacteria, and placed tablets soaked in different concentration of HCl on an agar plate and couple of days later we measured the circle of inhibition around the tablet. My question is, how far can the HCl spread to? Like one circle of inhibition was about 2 cm in diameter (with 2.0M of HCl). Going away from the center, how does the concentration of the HCl drop? I vaguely remember reading somewhere that the concentration of HCl decreases logarithmically when moving away from the center of the circle. Is that right? Thank you!

Would this catalyste be able to be used in conjunction with thermite to create a higher burning tempature?

There is a solution containing a mixture of carbonate ions and hydrogencarbonate ions. A few drops of phenolphthalein indicator is added into the solution, ammonium solution is added drop by drop into the solution following. When there's the sign of the permanent change of the colour of the indicator, my teacher calimed that all the hydrogencarbonate ions have been reacted through the reaction (HCO3 - + H+ ---> CO2 + H2O) My idea is that all carbonate ions did completely reacted instead.

Can someone please explain to me how to do this problem. The molarity and molality of potassium chloride solution are 1.000 mol/L and 0.9750 mol/kg. what is the solutions density? I got an answer of 1.101 g/ml. will someone show me how to do it and verify to see if my answers right?

Different types and kinds of storing fuels What will be the most dangerous way to store fuel if you must choose between gas / liquid. 1 Liter of Methanol Or 1 Liter of Hydrogen

i recently performed an experiment, with hcl and mg as i placed both into a eudiomter. how would air entering affect the way the reaction would occur?

Actually, Im a newbie to the site, great to be here. But the reason that I've stumbled across this forum was this question. "How much pressure, and at what temperature can you force a gas to become a liquid? I know like condensation and all those kiddie experiments blah blah blah, but Im actually interested to learn the type of materials and equipment it would require to take an amount of gas, and condense it into enough liquid to fill a small glass. Im thinking possibly pressure chambers and an extremely low temperature would produce this. If anyone could crunch some numbers and come up with the specifications required to do this it would be awesome. -MaZe

Why when HCl reacts with a metal the metal changes colors.

Can someone expain to me how to interpret a solubility curve, how you know what temperture a solution is soluble, and how you know if a solution is super saturated based on the soulubility curve.

Hi everyone, I am looking for a shop that sells equipment suitable for the range of experiments to be done at gcse (14-16 yrs old). I'm 26 and retaking my gcse science and would really appreciate some help! So any suggestions of shops that sell basic science equiment would be really helpful! thanks Marc

hello everybody i discovered by myself the process of transforming carbon dioxide into calcium carbonate. and i think this is the solution for problems concerning CO2 emissions in factories. i tested the process and luckily it works!(science project in highschool). Plz rep if you need more info.

PCL3 (g) + CL2 <---> PCL5 (g) in the equation above, the forward reaction is first order in both PCL3 and CL2 and the reverse reaction is first order in PCL5. a. suppose that 2 moles of PCL2 and 1 mole of CL2 are mixed in closed containers at a constant temp. Draw a graph that shows the concentrations of PLC3, CL2, and PCL5 change with time until after equilibrium has been firmly established. b. give the initial rate law for the forward reaction c. provide a molecular explanation for the dependence on the rate of the forward reaction on the concentration of reactants. d. provide a molecular explanation for he dependence of the rate of the forward re…