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Informally, a reaction is said to be fast if _______ are formed rapidly, like in a _______ reaction or an _______. A reaction is slow if the _______ are formed over a long period of time, like in ______ or the ______ of organic material.
- products
- percipitation
- explosion
- products
- corrosion
- decay
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In everyday life, a rate is defined as the ______ in a property by the _____ it takes for that change to take place.
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In chemistry, rates are expressed in terms of how quickly ______ are used up or ______ are formed. So the reaction rate is defined as either the _______ or the ______ divided by the ______ interval which the changes take place.
- reactants
- products
- product
- reactant
- time
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What is the formula for the average rate of consumption of reactants and average rate of formation of products. Explain the difference in the structure of the formulas
- Average rate of consumption: R = -Δ[R]/Δt
- Average rate of formation: P = Δ[P]/Δt
The 1st is negative because reactants are consumed in reaction while the 2nd is positive because products are formed
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H2(g) + I2(g) → 2HI(g)
In the reaction above, two HI molecules are produced from one H2 molecule. Therefore, the rate of formation of HI is ____ the rate of ________ of H2. Represent this numerically.
- twice
- consumption
- -Δ[H2]/Δt = (1/2)Δ[HI]/Δt
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In order to report rate without specifying the species, we use the ______ ______ _____. We get this figure dividing the ______ rate by the _______ _______. How would that work in the reaction: aA+bB → cC+dD
- unique average rate
- average
- stoichiometric coefficient
- unique average rate: -(1/a)Δ[A]/Δt = -(1/b)Δ[B]/Δt = (1/c)Δ[C]/Δt = (1/d)Δ[D]/Δt
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Most reactions _____ ____ as the reactants are used up. To determine the reaction rate at given instant during the course of the reaction, ____ concentration measurements must be taken and they must be as _____ in time as possible.
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The instantaneous rate is the slope of the _______ to the plot of concentration against _____ at the time of interest.
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To set up expressions for the instantaneous rate of a reaction, we consider the time interval Δt to be so _____ that t and t+Δt are very _____ together.
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Patterns in reaction rate data can often be identified by examining the _____ _____ of reaction, which is the _______ ______ occurring right at the start of the reaction. Why is recording this at the start of the reaction an advantage?
- initial rate
- instantaneous rate
- Presence of product during the reaction may affect the rate; but at the beginning of the reaction when there is no product present and we can be certain that the only things affecting the rate are the reactant.
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In a reaction, as the ________ of a substance falls, the _____ falls too. State the equation here using a rate constant. That equation is an example of a _____ law
- concentration
- rate
- Rate of reaction = k*[substance]
- rate law
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Rate law is an expression for the _________ reaction rate in terms of the ________ of a species at any given instant.
- instantaneous
- concentration
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Some reactions don't give us a straight line when we plot rate against the concentration. For example, NO2 in the reaction: 2NO2(g) → 2NO(g) + O2(g). In this case, the plot of the rate against the square of the concentration of NO2 is linear. This shows that the rate is proportional to the _____ of the concentration and therefore the rate at any stage can be written as:
square
rate of consumption of NO2 = k*[NO2]2
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What is the structure of the rate law formula? What do you call it when a = 2? Why?
Rate = constant * [substance]a
Second order, because the rate is proportional to the second power of the concentration
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Doubling the concentration of a reactant in a first order reaction doubles the _______ ______. What if we doubled the concentration of second order reaction, what would the factor of increase look like?
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The reaction: 2NH3(g) → N2(g) + 3H2(g), is an example of a _____ order reaction, a reaction in which the rate is independent of concentration of the reactant. What would the equation look like?
- zero order reaction
- Rate = k*[substance]0
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In the reaction: Aa + Bb → Cc + Dd, what would the rate and the overall order be?
Rate = k*[A]a *[B]b
Overall order = a + b
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The overall order of the reaction affects the ______ in the rate of consumption. Also, pressure (if known) can be used as a value for _______ in these equations.
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A negative order implies concentration appears in the _____ of the rate law.
denominator, [A]-1 = 1/[A]
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In the reaction 2O3(g) → 3O2(g), the rate = k*[O3]2/[O2] which is = k*[O3]2*[O2]-1, what is the overall order?
2+(-1)=1
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An _______ _____ _____ gives the concentration of reactants or products at any time after the start of the reaction.
integrated rate law
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The integrated rate law of a zero order reaction is easy to find because the rate is _______ (at k). The difference in concentration of a reactant from its ______ value, [A]0, is proportional to the time for which the reaction is in place. State one of the formulas
- constant
- initial value
- [A]0 - [A] = kt or [A] = [A]0 - kt
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Which formula lets us know when the reaction has come to an end?
- t= [A]0/k
- because then all the reactant has been consumed [A] = 0
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To find the concentration of reactant A in a first order reaction at any time after it has begun, we use which two formulas? The equations are forms of the integrated rate law of a _____ _____ reaction. Finally, state a variation of the formulas that takes the "y = intercept + slope * X" form. We use this to confirm if the reaction is in fact ______ _____ and to measure the rate constant
- ln[A]t/[A]0 = -kt
- [A]t = [A]0e-ktfirst order reaction
- ln[A]t = ln[A]0 - kt
- first order
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What is the difference between finding the average rate vs the unique average rate
average rate doesn't involve coefficients
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