CHEMISTRY COMMUNITY

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How can you tell, by looking at the different flasks, which one is at equilibrium? Is it when the number of moles of diatomic molecules is half that of it dissociated particles?

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When a reaction takes place within a calorimeter, a device in which heat transfers is monitored by recording the change in temperature produced by a process taking place within it, any heat lost from the reaction is absorbed by the calorimeter. Thus -q = q(cal).

(I hope this helps).

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Work happens when a system is pushing against an opposing force. Free expansion occurs in a vacuum, where the opposing external pressure is zero. Because there is no opposing force, no work is done during free expansion.

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Also, an additional tip to help you better understand which relation to use is knowing the relationship between Cp,m and Cv,m: Cp,m= Cv,m + R. Keeping in mind that molar heat capacity increases with molecular complexity, and knowing that you simply have to add R to the molar head capacity at constan...

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At constant pressure with no nonexpansion work, delta H is equal to q.

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The reacting gases (the gases that are actually part of the equilibrium constant) still occupy the same individual molar concentration/partial pressure within the reaction vessel so there is no change to the equilibrium constant.

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When adding an inert gas into the reaction vessel, the reacting gases continue to occupy the same volume, so their individual molar concentrations/partial pressures remain unchanged despite this addition of inert gas. Thus, the equilibrium constant with the addition of an inert gas remains unchanged.

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Yes, adding to the response above, as long as the k value corresponds to the correct temperature value (k1 with T1, and so on), it should be fine.

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When looking at the steps in a reaction mechanism, you can also distinguish the two by looking at where they end up getting placed. Intermediates aren't written in the final chemical equation because they get used up in the reaction- they become products in one step, and a reactant in the follow ste...

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The textbook gives a really good analogy to collision theory: Imagine playing pool (with billiard balls). Say you hit the ball with a low speed. All that happens is that the balls collide and bounce apart from each other. However, if you hit the ball with a high enough speed, the balls colliding sma...

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How can you tell whether or not a step in a reaction mechanism is slow or fast? Or is this told ahead of time?

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According to the textbook, the steady-state approximation assumes that any intermediate formed during a reaction remains at a constant, low concentration. The pre-equilibrium approach assumes that the rate of consumption of the intermediate in the slow step is insignificant relative to its rates of ...

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Reaction mechanisms are basically the sequence of steps that a reaction must undergo on the molecular level to go from reactants to products. It has to show the order and rate in which bonds form/break at each step and all steps must add up to give the overall balanced chemical equation for the reac...

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The different units for k:

For 0th order: molA/L*s
For 1st order: 1/s
For 2nd order: L/molA*s

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Why does one use freezing temperature to calculate the entropy of fusion at a substance's melting point? (Reference: 6th ed-Self Test 9.8B)

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Based on Self-Test 9.8A in the 6th ed. textbook, why is it that the standard entropy of fusion for mercury at its freezing point is a positive value? What is happening at the freezing point of mercury that validates finding the standard entropy of fusion (and not of freezing), and thus, using the en...

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When you are calculating the change in entropy for a system that was compressed suddenly and irreversibly, followed by change in temperature, you have to calculate both the change in entropy for volume change and the change in entropy for temperature change. For this particular question, why is that...

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(If I understand you correctly)

In the case when the system is isothermal (constant temperature) and the system is under constant pressure, work can be defined as the external pressure times the change in volume. If there is no change in volume, no work is done.

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Because each unit of the Kelvin scale (called a Kelvin) is equal to that (a degree) on the Celsius scale, they may have not included in units.

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I am not sure by what you mean by the energy of an isolated system being constant at equilibrium specifically, but the definition of an isolated system is a system that cannot exchange either matter or energy with its surroundings. There can be energy transformations within an isolated system, but t...

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An isolated system is defined as a thermodynamic system in which neither energy or matter can be exchanged with the surroundings. Work and heat can be done within the system, but this must be distinguished with whether or not there is a CHANGE in the internal energy within the system. The first law ...

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An isolated system is defined as a thermodynamic system in which neither energy or matter can be exchanged with the surroundings. Work and heat can be done within the system, but this must be distinguished with whether or not there is a CHANGE in the internal energy within the system. The first law ...

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You can cancel them out because they are on opposite sides of the equation! (one is a reactant, the other is product)

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Fusion happens when solids are heated to such a point that bonds holding molecules together break apart and the solid becomes a liquid. An easy way to put it is to say that fusion means melting. The input of heat makes the change in enthalpy positive, and the reaction endothermic. When you reverse f...

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OH- and H30+'s connection to autoprotolysis is the fact that water is an amphoteric molecule, meaning that it can act as both an acid and a base. This is relevant to autoprotolysis, a process in which a proton is transferred between two identical molecules (in this case water) that can act as both a...

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How do you write a net ionic equation so that you can use its results to calculate the equilibrium constant?

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In addition to what was said, activities are simple quantities that are introduced to facilitate writing the expression for K. All activities are pure numbers and thus, are unitless. In the simplified version of the equilibrium constant, activity is the numerical value of pressure in bars, or numeri...

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You should use a net ionic equation when a reaction involves fully dissociated ionic compounds in solution. A net ionic equation automatically gets rid of spectator ions, which are ions that exist in the same form in both reactant and product sides of the chemical reaction (thus, concentrations of s...

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For reactions involving fully dissociated ionic compounds in solution, how do you use the activity of each type of ion to write an equilibrium constant for the net ionic equation?

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The same method of calculating K is used to calculate Q. Q, the reactant quotient, is different from K when the reaction has not reached equilibrium, and depending on how much larger of smaller Q is from K, one is able to tell whether the forward or backwards reaction is favored. Like what the perso...

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A good example of this can be found in an example given during lecture in which we are required to find Kp for CaC03(s)-->/<-- CaO(s) +CO2(s). The ratio for the equilibrium constant would be Kp= P(partial pressure of)(CO2) because solids or liquids have such an irrelevant change in concentration tha...

CHEMISTRY COMMUNITY

Search found 31 matches

6th Edition 11.7

Re: q cal versus q reaction

Re: free expansion

Re: Heat Capacity at Constant Volume and Pressure

Re: ∆H and q [ENDORSED]

Re: adding an inert gas

Re: Inert Gas

Re: Arrhenius Equation

Re: catalyst vs intermediate

Re: collision theory

Slow or Fast Step

Re: Pre-Equilibrium vs Steady-State Approach

Re: Mechanism

Re: Units

Calculating Standard Entropy of Fusion

Standard Entropy of Fusion at Freezing Point (Self-Test 9.8A- 6th Ed.)

(6th edition) Example 9.5: Calculating Change in Entropy for T and V

Re: Work without change in volume

Re: Unit for Heat Capacity

Re: Energy

Re: Isolated System

Re: Isolated System

Re: method 1

Re: Reverse fusion

Re: Autoprotolysis

Net Ionic Equations

Re: Activity

Re: Net Ionic Equations for Equilibrium Constants

Equilibrium constants for ionic compounds

Re: Q vs K

Re: Liquids and Solids in Equilibrium Constants