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.
In order to calculate the energy of a reaction's ejectile, we make use of the concepts of the conservation of energy and momentum along with the reaction Q energy. However, if there is a threshold energy with above zero, meaning Q value is negative, do we have to consider the threshold energy as...
Homework Statement
I have some doubts about the method constructing chemical reaction process of quantum mechanics in the referencehttp://www.southampton.ac.uk/assets/centresresearch/documents/compchem/DFT_L2.pdf, for the example of ##H_2O## molecular dissociation to ##H^+## and ##OH^-## ions...
Homework Statement
The decomposition of phosphine 4PH3(g) + P4(g) + 6H2(g) is first-order with respect to phosphine with a rate constant k = 0.0155 s-l at 953 K. If the decomposition occurs in a constant-volume batch reactor at 953 K, calculate, for 40% conversion of PH3,
(a) the time...
Homework Statement
5.5 MeV alphas hit Be-9 and produce carbon with a gamma. the Q value is 10.65
I have to find the kinetic energy of the carbon nucleus and the gamma and I am to ignore the gamma ray momentum.
Homework Equations
T = p^2 / 2*m
Q = T_be + T_alpha - T_c - T_gam[/B]The Attempt...
I am wondering the answer to the following question, and what equation you would use to solve it:
What is the duration of the following reversible reaction?
A <--> B
You have 10 moles of A and zero moles of B.
After 1 minute, 25% of A turns into B, and 50% of B turns into A.
My class...
here is the question (part I):
For part I, I need some assistance, I cannot figure out how to do the question. I know eventually what to do, it's just working out the equilibrium constants I'm having trouble with. So to start, I want to work out the K values at 600K and 800K, I do this by...
Hey guys,
Sorry for this newbie question, I would to ask how to I obtain the reaction of the pinned connection of A, B, and C (See attachment)? Do I really have to use Force-Method? I actually attempted to use Moment at different places and do simultaneously (Idk if it's the right thing to do)...
Homework Statement
A uniform horizontal rod of mass 4 kg and length 500 mm, is hinged at the left hand side and supported at rest by a chain (S) attached 10 cm from the hinge.
Calculate the magnitude and direction of the reaction force on the rod at the hinge. State the principle you have...
How would one approach part I and II? In terms of thermodynamics I'm not sure how I can show that this hypothesis is true. Could I work out the equilibrium constant and make a decision based on its magnitude? For example if it is >>> 1 then the hypothesis is true, would that be correct?
For the...
Alright, I have a basic understanding about anti hydrogen - hydrogen annihilation reaction. But what exactly happens if an anti hydrogen atom stumbles into anything else like a deuterium, tritium of helium atom?
From my limited understanding, antimatter can only react with its anti-particle...
I'm trying to solve one of the problems in my textbook (Atkins Physical Chemistry) and I just can't get it out. Here's the problem:
"The data below apply to the formation of urea from ammonium cyanate. Initially 22.9g of ammonium cyanate was dissolved in enough water to prepare 1.00 dm3 of...
Homework Statement
The complete combustion of methane is represented in the following equation:
CH4(g) + 2O2 -> CO2(g) +2H2O(g) +802.5 kJ
Assume that natural gas is essentially methane. The emission level of Carbon monoxide, CO(g) from the burning of natural gas is 19.14kg/MJ of energy...
Pronouncing a nuclear reaction like
as "one,zero,neutron + 235,92,uranium yields 141,56,barium + 92,36,krypton + 3,1,0,neutron" is awkward. How is it pronounced by physicists in practice?
Hi folks,
I was thinking about an old physics olympiad question I read. Can't remember exactly but it was about minimising the reaction force of a skier as she took a curved path down a ski-slope. That got me thinking generally about what is going on with the reaction force in such a situation...
Homework Statement
Homework Equations
Δ[A]/aΔt = Δ[ B]/bΔt
The Attempt at a Solution
Δ[ I]/3Δt = Δ[H]/2Δt = 7.8E-4. What exactly am I supposed to do for this?
I am a high school student in Hong Kong studying Physics. I am having some problems about atmospheric pressure. Imagine there is a cube block with volume 1 m3 and top surface area 1 m2 . The cube block is being placed on the floor and it has mass of 1 kg. What is the normal reaction force F...
Homework Statement
when fission occurs why neutron get less energy as compare to the daughter nuclei? i need both physical and mathematical explanation.
Homework EquationsThe Attempt at a Solution
i think it is due to the small mass of neutron. but i am not sure as it is not satisfactory. a...
Hello. Where is come from the heat (about 17,59MeV) from reaction deuteron + tritium -> Alfa + netron + Q although sum of substrates's mass is greater than sum of products's mass?
I need to design an ammonia production process but I can't find the kinetic info from the articles online. The catalyst will be iron. Can somebody explain how to find kinetics data and conversion rate? I found some articles but there was no conversion info on them.
Hi there,
I was thinking that static friction works in opposition to a reaction force like the force of a fridge against you as you push it. However, since you are pushing horizontally and friction works against you why is it equal or greater than the reaction force? Will the force get...
Homework Statement
Given the reaction K2CO3(s) + 2HCl(aq) → 2KCl(aq) + CO2(g) + H2O(l), I need to find the enthalpy change in J, given that:
The specific heat capacity of water is 4.2J g-1 °C-1, and
The mass change of potassium carbonate is 2.98g, and the temperature change was °6C, and the...
Hello, I am reading about this and I have a question , so let me explain how I understood this and please correct where I am wrong. I will ask about nuclear reactors because obviously in bombs only prompt neutrons matter since there is no need for any control only an exponential increase in...
Good evening,
I am new to this forum and do not have a strong physics background. So if my questions seem woefully inept please respond with a simple laymans answer.
I understand that there are 2 basic ideas for fusion containment, and that the main 2 components of any successful fusion...
Hi guys,
First of all, thank you for your help. I am new in Ansys and Fluent (less than a month), hoping to learn.
I am trying to model a simple and single surface reaction
CH4 (g) -> C(s) + 2H2 (g)
on a "CVD reactor" to grow C(s) (graphene, or graphite). The inlets are gases inyections of...
I do not have a clear concept about half-reactions...Can someone please give the half reactions for following reaction,
Zn^0 + 2H^1 Cl^-1 -----> Zn^+2 Cl2^-1 + H2^0
or Zn + HCl ----> ZnCl2 + H2
good morning,
I'd like to know if exsists a classical explanation and, of course, qualitative about the nuclear fission / fusion reactions.
I would like to explain the development of external energy to considering only nuclear forces system
in terms of internal mechanical energy and the fact...
Homework Statement
In each of the diagrams (please see attached file (I am sorry for the rotated, the original was in normal form but when uploading it, it was somehow rotated)) and the description of each case below, a particle is moving on a smooth surface, so that the reaction force R acting...
Homework Statement
The modulus of elasticity of each member is E = 20kN/(mm^2) and the cross section of each member is 1000(mm^2) , except member EB and EC is 40(mm^2) , determine :
a) The vertical displacement at joint C
b) The horizontal dispalcemnet at joint C
at A , it's a pinned...
Homework Statement
Write separate equations for each potassium salt (KH2PO4) dissolving in water and for the ionization reaction of the weak acid anion that each of these salts contains.
Homework Equations
None
The Attempt at a Solution
I just needed to clarify when it dissolves in water do...
By conversation of momentum, the rocket can be propelled forward by ejecting mass like gas.
However, how is the propelling force explained in terms of action and reaction? If gas is ejected, what does the force act on?
Homework Statement
Rod of length b and mass m topples from vertical position at theta = 0. Calculate the reaction force f as a function of theta. What is the minimal and maximal values of f for theta between 0 and pi
Homework Equations
Third law?[/B]The Attempt at a Solution
I never really...
1. Homework Statement
2. Homework Equations
rate law equation
3. The Attempt at a Solution a) I would expect this reaction to be a multi-step reaction because there are six reactant molecules, as shown in the overall chemical equation. For this reaction to be one-step, all six molecules...
Homework Statement
A beam of ##^{50}##Ti nuclei impinged on a ##0.5 mg/cm^2## thick ##^{208}##Pb target in an experiment lasting 176 hours. During that time a total of ##3260 \; ^{257}##Rf nuclei were detected. The beam intensity was throughout the experiment constant at ##6.6\mu A##. Each...
Homework Statement
What is the maximum reaction force exerted by a seat on the passenger of a ferris wheel? There's a diagram showing the seat at 6 o'clock, 12, 3, and 4:30... on a 12 hour clock.
Homework Equations
N/A
The Attempt at a Solution
I guess the reaction force is the normal force...
Hello,
I have a problem
Basically, in theory -- a damaged 1220mm dia pipeline sub-sea (-8msw) with a 500mm hole in the 12oclock position 600mm. Pipeline resting on the seabed
The goal of the problem is to flush the pipeline of its contents in both directions.
The idea - have a containment...
Homework Statement
Homework Equations
The Attempt at a Solution
2(255) - [(1)(159) + (1)(243)]
= +108KJ
The answer key says its b) -108KJ. Am i doing something wrong or is the book wrong?
I have an assignment in which I must find a named reaction, the original reference to it, and show what experimental evidence was used to develop the reactions mechanism. So far I've had no luck finding anything. It's hard enough finding the original reference and so far I haven't been able to...
For organic chemistry we typically look at the stability of the end product to determine if the reaction will proceed. For instance for an Sn2 reaction we would check if the product anion is more stable or less stable than the nucleophile attacking - if the product anion is more stable than the...
Dear all,
As we know, the reaction rate can be calculated as following:
R = N * σ * Φ (1)
Where R is reaction rate (events/s/cm3)
σ is cross section (cm2)
Φ is flux of incident particle beam (particles/s/cm2
N is density of target (atoms/cm3)
Logically, there is a limitation of R, because...
Homework Statement
Hello all, I am doing this lab http://scc.scdsb.edu.on.ca/Students/onlinecourses/Sikora/sch4u/v12/60.pdf
i am stuck on trying to find hte concentration of ch3cooh
Homework Equations
n = m / M and c = n*vand i think the ideal gas law could be used but not sure
The Attempt...
Homework Statement
Consider the decomposition of N2O5:
1. N2O5 → NO2 + NO3
2. NO2 + NO3 → NO2 + O2 + NO
3. NO + N2O5 → 3NO2
a) Find the reaction for the decomposition of N2O5 to stable products
b) Find the steady-state concentration of the intermediate(s)
c) Use the previous to show how the...
Hi everyone! I know that the Election Day thread has now been locked by the moderators, but I felt I had to respond to Donald Trump winning the 2016 US Presidential Election.
I had a swirl of emotions floating inside of me, from shock (despite knowing that there was a reasonable chance that...
Homework Statement
Homework EquationsThe Attempt at a Solution
Can't find this exact reaction mechanism online. Help?
http://imgur.com/a/X9P7e
I don't know what the mild oxidation does. Does it split the double bond into a ketone and aldehyde?
i.If all the calcium carbonate used in set up X was used up for the reaction, what is the amount of moles of carbon dioxide produced during the reaction ? (Ca = 40, C = 12, O = 16)
My progress:
Molar mass of CaCO3=(40+12+(16*3))gmol-1=100 gmol-1
Molar mass of CO2=12 + 16* 2 gmol-1=44 gmol-1...
Homework Statement
A control rod to limit the rate at which a nuclear reactor is working is made from boron which is sealed in a casing. A boron atom (105B) is able to capture a neutron; an atom of lithium (Li) and an alpha particle being produced in the process. As a result helium gas is...
Hey,
I have a simple ANSYS model shown in link:
https://dl.dropboxusercontent.com/u/104865119/hand_calc.PNG .
Ansys reaction force in z axis is +121 N and -121 N. Can someone clarify how do you
get to this result using hand calculations?