A chemical reaction is a process that leads to the chemical transformation of one set of chemical substances to another. Classically, chemical reactions encompass changes that only involve the positions of electrons in the forming and breaking of chemical bonds between atoms, with no change to the nuclei (no change to the elements present), and can often be described by a chemical equation. Nuclear chemistry is a sub-discipline of chemistry that involves the chemical reactions of unstable and radioactive elements where both electronic and nuclear changes can occur.
The substance (or substances) initially involved in a chemical reaction are called reactants or reagents. Chemical reactions are usually characterized by a chemical change, and they yield one or more products, which usually have properties different from the reactants. Reactions often consist of a sequence of individual sub-steps, the so-called elementary reactions, and the information on the precise course of action is part of the reaction mechanism. Chemical reactions are described with chemical equations, which symbolically present the starting materials, end products, and sometimes intermediate products and reaction conditions.
Chemical reactions happen at a characteristic reaction rate at a given temperature and chemical concentration. Typically, reaction rates increase with increasing temperature because there is more thermal energy available to reach the activation energy necessary for breaking bonds between atoms.
Reactions may proceed in the forward or reverse direction until they go to completion or reach equilibrium. Reactions that proceed in the forward direction to approach equilibrium are often described as spontaneous, requiring no input of free energy to go forward. Non-spontaneous reactions require input of free energy to go forward (examples include charging a battery by applying an external electrical power source, or photosynthesis driven by absorption of electromagnetic radiation in the form of sunlight).
A reaction may be classified as redox in which oxidation and reduction occur or nonredox in which there is no oxidation and reduction occurring. Most simple redox reactions may be classified as combination, decomposition, or single displacement reactions.
Different chemical reactions are used during chemical synthesis in order to obtain a desired product. In biochemistry, a consecutive series of chemical reactions (where the product of one reaction is the reactant of the next reaction) form metabolic pathways. These reactions are often catalyzed by protein enzymes. Enzymes increase the rates of biochemical reactions, so that metabolic syntheses and decompositions impossible under ordinary conditions can occur at the temperatures and concentrations present within a cell.
The general concept of a chemical reaction has been extended to reactions between entities smaller than atoms, including nuclear reactions, radioactive decays, and reactions between elementary particles, as described by quantum field theory.
1. It has been found by experiment that the molar mass of the Rn nucleotide is 221.9703 g and that of the Po nucleotide is 217.9630 g. The molar mass of helium is 4.00150 g. Given this information, and the information from the class, calculate the energy evolved, in kJ, for the following nuclear...
Homework Statement
For each reaction, give balanced chemical equations or NR (no reaction) and rationalize your answers in terms of trends in oxidation states. Calculate net potential for the reactions:
a) Fe2+(aq) + Co3+ (aq) (acidic conditions) →b) CrO42−(aq) + MoO2(s) + H+ (acidic...
is it possible to have a triple replacement type reaction? I know of single and double replacement but what if you mix sodium carbonate, magnesium hydroxide, and potassium sulfate all together (this is all made up just for an example).
would all the different ions mix to form all possible...
I thought I understood it cause I always had the right answer ever since I learned about it.
But now my friend asked me a question about why does a piece of chalk break if you put a heavy thing on it, say a car.
If we just think about action and reaction, the forces have to be along a...
Homework Statement
Topic
Homework Equations
http://en.wikipedia.org/wiki/Horner%E2%80%93Wadsworth%E2%80%93Emmons_reaction
This is basically a variation of a wittig reaction.
The Attempt at a Solution
I'm trying to understand this concept, because the chemistry gods have decided that it...
Homework Statement
See attachment there is reaction.why --OH attach to 2nd carbon. why not it attach first carbon(from left).
Homework Equations
steric hindrance
The Attempt at a Solution
there seems greater steric hindrance in right carbon(2nd from left) than left one.
Homework Statement
Human reaction times is sometimes worsened by alcohol. How much farther would a drunk driver's car travel before he hits the breaks than a sober drivers car? assume both cars are initially traveling 49 mi/h the sober driver takes .33s to hit the brakes and the drunk driver...
This is the link for the assignment: http://imageshack.us/f/840/assignmentsynthesisofev.jpg/
Homework Statement
Given in the link
Homework Equations
Why would the proposed synthesis be successful if the reaction stopped after 2 hrs?
How does H attack compound 2 to create compound...
I am having trouble understanding what exactly happens in an exothermic reaction. Specifically, I need to answer the following question:
In an exothermic reaction:
a) the kinetic energy increases and the potential energy decreases.
b) the kinetic energy and the potential energy decrease...
First of all, I'm asking here for advice since I've seen how the members of this forum answer in a mature manner (I've read some problems like mine in the forum, however, I've not contributed some). your advice is very much appreciated (please don't mind the different field of study)
I've...
Suppose you have a reaction wheel or a control moment gyroscope on your spacecraft for attitude control. This would be a self contained unit, with 3-axis control. Either device utilizes the conservation of angular momentum, trading angular momentum between the unit and the spaceship frame as...
hi,
The drawing show 2 transformers T1 and T2. Each primary of transformer is at fixed voltage (110 volt for example), but one transformer is with 0° phase and other with 180° phase. The secondary of each transformer has the same charge and the same current. The idea is to cancel the flux from...
consider
3A + 5B ----> 4C + 2D
if this is an elementary process
the rate of reaction is given as
r = k [A]3 [ B ]5 , where k is rate constant, [x] are concentrations
so my question is , why is the rate of production of A = 3 times the rate of reaction?
since the rate of reaction has...
Homework Statement
I am reacting methyl salicylate with sodium hydroxide to produce salicylic acid. However, first it is important to add acid to neutralize the very basic solution.
My question is, when determining the amount of HCl to add, do I need to take into consideration the methyl...
The problem statement says to derive the concentration as a function of time for the general three species first order reactions. I have attached an image of the problem, so see the image for the reaction.
I have written the reaction rates for all the reactions but I am having trouble...
A 9g sample of solid NH4Cl is heated in a 4L container to 924.4oC and decomposes according to the following equation.
NH4Cl(s) -> HCl(g) + NH3(g)
at equalibrium the partial pressure of NH3 (g) is 1.346 atm. Calculate the equilibrium constant for Kp for this reaction
Homework Equations...
Please help Due in 2 hours. Statics machine equilibrium: reactions- too many unknowns
Homework Statement
The woman using the lat pulldown machine is holding the 80-lb weight stationary in the position shown. What are the reactions at the built-in support E and pin support F? (A and C are...
Latley, I have been trying to conduct an experiment dealing with Potassium Carbonate and water. But first I need to get everything down on paper. So, what is the reaction between water that is 145 degrees and 30 grams of Potassium Carbonate? Would it help if I put the PC in the water and then...
A chemical Reaction A-->B is carried out in a closed vessel. The following data are taken for the concentration of A, Ca (g/L), as a function of time, t(min), from the start of the reaction. A proposed reaction mechanism predicts that Ca and t should be related by the expression
ln...
Two lightweight metal spheres are suspended near each other from insulated string. One sphere has no net charge, the other has a net charge. The spheres will?
Homework Equations
None
The Attempt at a Solution
I know opposite charges attract and similar charges repel, but not sure...
This question is about momentum in a system when an electron and positron annihilate each other.
Consider the following, please:
SITUATION
Consider a system of 3 particles. They are in motion (which I will explain with Earth as the geometric frame).
The electron (#1) is moving, coming from...
Homework Statement
Histidine is an amino acid. It is not soluble in water but it will dissolve in water when dilute sodium hydroxide is added.
The question has two parts to it:
part-a)
Write an equation for the reaction that occurs between histidine and dilute sodium hydroxide...
I'm in my 3rd year of a chemistry course so its fairly ridiculous that I can't balance equations. I can balance simple equations in my head in seconds but what I need is an algorithm that I can use to balance any equation I will ever encounter. Can any of you teach me a method for balancing...
Homework Statement
Basically I have to show the product of this reaction:
Homework Equations
Grignard reaction mechanism:
The conversion of a ketone to an alcohol
The Attempt at a Solution
My attempt of this reaction produces an alcohol with two ethyl groups attached to...
I thought heat increased reaction rates, meaning that when something is at equilibrium, it should increase both the forward and reverse reaction rates...
Is this wrong?
Then why does Le Chatelier's principle predict that a temperature increase favors the endothermic direction?
For a piece of coursework I have to design a shaft for a windturbine.
The shaft has a load on one end due to the rotor blades and a load on the opposite end due to a sprocket which is chain linked to a generator. The supports are bearings in between the two loads, as shown in this drawing...
Homework Statement
n-butyl alcohol was reacted with potassium bromide in the presence of concentrated sulphuric acid and water.
1) Is hydrobromic acid involved in this reaction? If yes, how so?
2) Is this reaction SN1 or SN2? What is the mechanism?
3) What is the purpose of the...
i am working on a hoop and its 550mm diameter, 7mm thickness. I applied 1mm displacement from its upper face which is normal to its direction.Stress is 730Mpa which is normal but the total reaction force is 0.0004N which is too low. where do i make the mistake.Material is structural steel...
Classical charged particle's reaction to a retarded field
This is something I've been curious about for a while -- every once in a while, I'll see some random reference to it in an article, but I never feel like it's the whole story.
The situation is this -- you have a moving classical...
Dear all,
I am not an expert of Chemistry and I would like to know if there is a reversible reaction that can be activated only by thermal energy. The result of the reaction should be something which can be brough again to the initial state, releasing again the thermal energy stored. I was...
Homework Statement
Reaction time can be crucial in avoiding a car accident. You are driving at 75 km/h [N] when you notice a stalled vehicle 48.0m directly ahead of you. You apply the brakes, coming to a stop just in time to avoid a collision. Your brakes provided a constant acceleration of...
Hello,
I'm making a question on the explosion of hydrogen/oxygen. All the things you need to know are the following. The formation of H-radicals in the H2-O2 mixture are responsible for ignition of the explosion. This means the H-radicals need to be formed faster than they are destructed to...
Homework Statement
http://img101.imageshack.us/img101/9546/3dstats.jpg
Pole AB is supported at point A by a pin joint, and held at point B by two wires, BC and BD, as described in the drawing. At point B acts on the pole force F which equals 500 [N]. The force F acts on a horizontal...
Homework Statement
The apparatus below shows an experiment to investigate the speed of reaction between lithium and water. A piece of lithium is wrapped in steel gauze and placed in a beaker of ]water. The volume of gas collected in the measuring cylinder is measured at 10s time interval...
Which fundamental force mediates the reaction \pi^+ + D \rightarrow p + p?
My initial assumption was the strong force because states only feature quarks (i.e. there are no leptons) but looking at it again I'm not 100% sure.
Do I need to include colour factors? Could it be a neutral current...
Redox reaction...with a twist!
In the chlor-alkali process OH–(aq) and Cl2(g) are produced by the electrolysis of a saturated solution of sodium chloride. Explain why chlorine gas rather than oxygen gas forms at the anode.
The solution to the question has the word "Overpotential" and I...
Just need some clarification as to whether or not I'm doing this right. 1 drop HCl and several drops KMnO4 added to 2mL NaHSO3.
HSO3- → HSO4- + 2e-
MnO42- + 4e- → MnO22-
2HSO3-(aq) + MnO42-(aq) → 2HSO4-(aq) + MnO22-(aq)
A few questions:
-Since NaHSO3 is not an acid, the hydrogen atom...
Hello,
I need a few compounds that i can use that are soluble with water that causes the water to cool, so that if ingested it will not do any harm. your advice would be greatly appreciated, also if you may include a chemical formula if it is known. THANK YOU.
P.S. this is out of interest...
Homework Statement
What are the two final products when cis-2-butene reacts with HBr and CH3OH?
Homework Equations
Reactions of Alkenes.The Attempt at a Solution
I'm not sure if the HBr will attack the double bond first or if the OH on methane will take the H off HBr and create a radical...
There's a catalyst pellet in a reactor and I'm supposed to prove an equation for the maximum temperature which is:
Tmax=Ts +[(-H)*(D*Cas)]/k
First thing I did was develop an Energy Balance across the spherical catalyst and I got the following equation:
(1/r^2)*d/dr(r^2*k*dT/dr) +...
Hi,
I have been studying the radiation reaction problem and I see a weakness in the derivation that hopefully someone might illuminate for me. In the textbooks by Griffiths and Jackson, as well as some journal articles I have found, the radiation reaction seems to be "derived" by a suggestion...
So if I have a general reaction diffusion equation and perform a liner stability analysis on it I would only get the domains in which Turing Instability occurs but not which pattern I would get (stripes , spots etc.). So I need to use a nonlinear analysis. One technique people use is a...
i've got thoughts about a series of chemical reactions that would simply keep on repeating. perhaps by time release. the thought is to use this perpetual chemical reaction to create a battery that releases the electrons then has a series of chemical reactions eventually resulting in the two...
Hi guys,
I'm wondering how the wall of the cantilever beam (a beam fixed at one end at a wall) can exert a reaction moment? Is this done by the wall pushing back on the cantilever beam away from its centroidal axis?
Also is the reaction moment always applied to the centroidal axis of the...
I want to know the fundamentals of finding the force reqd for moving a stationary object such as a car or a segway (which has got two wheels).
Also let me know in a formula mu = F/ NORMAL REACTION,
WHAT IS THE VALUE OF A WEIGHT HAS TO BE TAKEN?
meaning if weight of a person standing on a...
Homework Statement
Homework Equations
The Attempt at a Solution
The problem I'm having is that I'm not sure how to work out the reaction forces because of the applied moment of 50kN.m. I know that the formulas are the sum of forces in a single direction equals 0 and the sum of...