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State the two conditions of molecules for a collision to be effective
Molecules must collide with the proper orientation and speed (energy)
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Define Activation Energy
Activation Energy is the minimum amt of energy substances must have for a reaction to occur
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According to Ref J, will this reaction occur? Explain
Zn (s) + MgCl2 (aq)
No Zinc is less active than Mg and can not replace it
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Explain which substances will react:
NaCl(s) with AgNO3(s)
or HCl(aq) with NaOH(aq)
The aqueous solutions will react, not the solid reactants, due to the free moving particles in a solution.
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Which type of substance reacts faster, ionic cmpds or covalent?
Ionic substances react faster than covalent.
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In terms of collision theory, why does an increase in temperature inc the rate of a rxn?
An inc in temp speeds up the molecules thus inc the number of collisions. The result is an inc in the rate of the rxn.
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In terms of energy, why does addition of a catalyst speed up a rxn?
A catalyst lowers the activation energy and so inc the rate of the reaction.
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Explain why pressure only affects gases.
Gases can be affected by pressure because thier molecules are so far apart unlike a solid or liquid whose particles are close together.
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Define activated complex
The activated complex is a short-lived substance that must be formed in order for a reaction to occur.
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Define endothermic
Endothermic reaction has a net gain of heat. Energy is a reactant.
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Define Exothermic
Exothermic is a net loss of heat. Energy is a product.
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How is ∆ H calculated?
∆ H = energy of products - energy of reactants
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What is enthalpy?
Enthalpy is the change in heat of a rxn or ∆ H
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State the units in which heat and temperature are measured
Heat is measured in Joules and temperature is measured in celsius or kelvin.
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Of what is temperature a measure?
Temperature is a measure of kinetic energy.
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Is this rxn exothermic or endothermic?
Rxn is endothermic
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Label A, B, and C
- A is the Activation Energy of the forward rxn, B is A. E. of reverse, and C is change in heat.
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For any reversible reaction, Compare the ∆ H of the forward with the ∆ H of the reverse.
The ∆ H of the forward reaction is always equal to the ∆ H of the reverse.
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On a potential energy diagram, what values can a catalyst not change.
- A catlyst does not change the value of
- ∆ H, the reactants or the products.
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Compare the value of the reactants and products in an exothermic rxn.
The products are at a lower potential energy than the reactants in an exothermic rxn.
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