Unit of reaction

The units of reaction rate are molar per second, M/s, or, equivalently, moles per liter second, mol/(L s). We define reaction rate in terms of concentration (moles per liter) rather than amount (moles) because we want the rate to be independent of the scale of the reaction. When twice as much 0.0200 M N2O5 decomposes in a vessel of twice the volume, twice the number of moles of 02 form per second, but the number of moles of 02 per liter that form per second is unchanged. 

Concentrations of trace constituents of the atmosphere are sometimes expressed in molecules/cm3. If those units are used for concentrations, what are the units of reaction rate ... 

The defined unit of reaction for acids and bases is the neutralization reaction... 

The rate at which a reaction proceeds can be followed by measuring the concentration of either the reactant or product. If dx represents the amount of the reactant changed during a small interval of time dt, then the reaction rate is represented by dx/dt. If, on the other hand, dc represents the concentration of the reactant left behind after a short interval of time dt, then the reaction rate is also represented by -dc/dt. The negative sign implies that the concentration of the reactant decreases with time or rate of reaction decreases with time. The unit of reaction rate is mol L I s-1. 

Since the left-hand side of the expression has the units-of-reaction rate (molL 1s 1), then these units must also apply to the right hand side (balance of dimensions). Therefore, the units of /c[A] must be molL-1 s l, implying that k has units of s l. Thus, simple dimensional analysis leads directly to the general expression for the units of a particular constant in a particular reaction scheme. 

FIGURE 14 Windows of reality for chemical reactivity per unit of reaction volume. 

In this reaction 2 mol of electrons is transferred for every unit of reaction —that is, for every 2 mol of Cr2 + reacting with 1 mol of S4062- to form 2 mol of Cr + and 2 mol of S2O32-. Thus n = 2. Then... 

Standard free energy change the change in free energy that will occur for one unit of reaction if the reactants in their standard states are converted to products in their standard states. (10.9) Standard free energy of formation the change in free energy that accompanies the formation of one mole of a substance from its constituent elements with all reactants and products in their standard states. (10.9)... 

In general, initiation should be as fast as is practical to produce as much polymer as possible per unit of reaction time. The reaction cannot be allowed to proeeed more quickly than the rate at which the exothermic heat of polymerization can be removed from the system, however. The decomposition rates of free-radical initiators are very temperature sensitive (the fi/2 of benzoyl peroxide drops from 13 hat 70°C to 0.4 h at 100°C), and a runaway reaction can result from overheating if the rate of initiation is not limited appropriately. 

According to thermodynamic convention a spontaneous cell reaction has a negative free-energy change numerically equal to the electrical work (in joules) per unit of reaction as written. In general, the total free-energy change is... 

The rate of acetylene hydrogenation on a clean Pd( 111) model catalyst has been measured using a high-pressure reactor incorporated in an ultrahigh vacuum chamber [87]. This allows the reaction to be carried out on clean, well-characterized samples. This yields a kinetic rate equation (in units of reactions/site/s) of the form ... 

Furthermore, we have called a change involving the increase of by unity one equivalent of reaction. This is not entirely satisfactory since it is neither necessary nor always customary to write the stoichiometric equation for a reaction so that one chemical equivalent of each reactant and product is involved, but once the stoichiometric equation has been written down in order to define what is meant by the unit of reaction is also defined. The French phrase la reaction a marche une fois does not admit of direct translation. An alternative suggestion j has been made that when increases by unity the reaction should be said to have advanced by one de donder. 

The last two thermodynamic parameters listed also deal with the pressure generated. The moles of gas generated per unit of reaction mass, along with the void space of the container, will be used in determining the maximum pressure which will be reached in the closed vessel. The pressure measurements are significant since the pressure and the integrity of the container will determine the potential for rupture of the container. 

We also discussed the choice of the reactor. A batch reactor has a much larger volume per unit of reaction product and tank like pressure vessels are much more expensive than cylindrical vessels. This combined with the difficulties of handling catalyst slurries and above all of preventing losses of the often rather expensive catalysts made us consider continuously operating reactors with fixed catalyst beds too. We eventually chose for the packed bubble column as a well suited reactor. 

Reagents are frequently used for precipitation reactions and the defined unit of reaction is the amount which provides Aa positive (or negative) charges. For example, for AgN03 one equivalent is the same as one mole, but for BaC one equivalent is one-half mole. 

The term reaction rate denotes the rate of a reaction in a general way. We now define it specifically as the moles reacting per unit of reaction space per unit time. The reaction space can be the empty volume of the reacting space, void volume of the catalyst bed, volume of the catalyst, weight of the catalyst, surface area of the catalyst, or volume of one or all of the phases present in a heterogeneous system. Where time is concerned, its definition depends on the type of reactor used. There are essentially two broad classes of reactors batch and flow. In a batch reactor, time (0 corresponds to the elapsed time from the start of a run. In a flow reactor, it is given by... 

In this reaction, 2 moles of electrons are transferred for every unit of reaction, that... 

The usual units of reaction rate used in this book are mol dm s h... 

Standard free energy change the change in free energy that will occur for one unit of reaction if the reactants in their standard states are converted to products in their standard states. (10.9)... 

The value which defines the intensity of gas dissolution in the gas-liquid reaction mixture flow in the device is the sulfite number of the reactor , i.e., the amount of oxygen absorbed by a unit of reaction volume per unit of time ... 

Reaction rates r are all expressed in moles per unit of reaction volume per second. If solid catalysts are involved, it is more convenient to express reaction rates per unit mass (rw) or unit surface area (rg) of catalyst. 

How much material do you need to supply to customer—100 g, 1 kg, 10 kg How much product can you obtain per unit of reaction volume (substrate/product solubility) ... 

How long does one batch take to run in process per unit of reaction volume How long do you have to make your delivery How large is the reaction vessel How long can the vessel be practically and safely operated ... 

In this reaction, 2 moles of electrons are transferred for every unit of reaction, that is, for every 2 moles of Cr " reacting with 1 mole of 8406 to form 2 moles of Cr + and 2 moles of 8203 . Thus n... 

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