Chemical Kinetics and Reaction Orders Quiz

55 Questions

What is the expression for the rate of a reaction?

dc/dt

What is the specific rate constant for a single-step reaction?

What does the half-life of a reaction refer to?

The time required for one-half of the material to disappear

What does molecularity provide complete detail about?

Order of reaction specially those of several steps

According to kinetic study, how is the rate of a reaction determined?

By the slow step

What is the first-order rate constant for an ordinary solution?

-d[C]/dt = kf[C]

In the case of a suspension, what is the relationship between Kf, solubility, and K0?

K0 = Kf x Solubility

What does the second-order equation describe?

Bimolecular reactions

What does the rate law for second-order reactions depend on?

The product of the concentrations of A and B raised to the second power

How can the rate law for second-order reactions be integrated and written according to 3 possibilities?

Using the initial concentrations of A and B, and the concentration of each species reacting in time t

What is the value of k for the decomposition of hydrogen peroxide?

0.0277 min^-1

How is the half-life (t90) related to the initial concentration and k?

t90 = 0.10[A]o /k0

What is the time at which the drug will have decomposed to one-half of its original concentration?

40 days

Which equation is used to calculate the value of k for the hydrogen peroxide decomposition?

k = 2.303 𝐶0 log 𝑡 𝐶

What does the value of k represent in the context of chemical kinetics?

Rate constant for the reaction

How does the dielectric constant affect the rate constant of an ionic reaction?

It increases the rate constant

What factor affects the rate of reactions depending on the polarity of the reactant?

Solvent polarity

What equation is used to calculate the shelf life (t90%) from K25°C?

$t90% = 0.105/ K25°C$

What does the equation log 𝑲𝟐 𝑲𝟏 = 𝑬𝒂 𝑻𝟐−𝑻𝟏 ( ) 𝟐.𝟑𝟎𝟆𝑹𝑻 𝑻𝟐𝑻𝟏 represent?

Arrhenius equation

What does the plot of logarithm of rate constants (k) against reciprocal of absolute temperature allow to calculate?

$K_{25°C}$

What does the ionic strength affect in a reaction?

Rate of reaction for ionic compounds only

What is the rate law for a second-order reaction?

Rate = -d[A]/dt = k[A]^2

What is the relationship between Kf, solubility, and K0 in the case of a suspension?

K0 = Kf x solubility

What is the rate law for an ordinary solution with no drug reservoir according to the provided text?

-d[C]/dt = kf[C]

What does the expression -d[A]/dt = K0 represent in the context of chemical kinetics?

Rate law for an ordinary solution with no drug reservoir

What does the second-order equation describe in chemical kinetics?

Rate of decomposition of A and B

What is the equation for the rate of decomposition in a second-order reaction?

-d[A]/dt = k[A]^2

What is the order of the reaction with respect to acetic anhydride?

First order

What is the order of the reaction with respect to ethyl alcohol?

Second order

What is the overall order of the reaction?

Second order

If the alcohol is in large excess and only a small amount is used up in the reaction, what is the order of the reaction?

Zero order

What process may affect the stability of drugs in liquid, solid, and semisolid products?

Hydrolysis, oxidation, isomerization, epimerization, and photolysis

What is the relationship between K observed, KOH, OH−, [OH−], and Kw?

$K observed = KOH - OH− [OH- ] = Kw/ [H+ ]$

Which type of pharmaceutical decomposition process can affect the stability of drugs in various products?

All of the above

What does the rate equation $Rate= − rac{d(CH3CO)2O}{dt} = k [(CH3CO)2O] [C2H5OH]^2$ indicate about the rate of reaction?

$Rate$ increases exponentially with concentration changes in acetic anhydride.

What is the relationship between the stability of thiamine hydrochloride and pH?

It is most stable at pH 2 to 3 and unstable above pH 6

What does molecularity classify the reaction into?

Unimolecular, bimolecular, and trimolecular

What does chemical kinetics study in relation to drug products?

The rates and mechanisms of reactions, particularly the decomposition and stabilization of drug products

What does the logarithm of rate constants (k) at various temperatures plotted against reciprocal of absolute temperature allow to calculate?

Activation energy

How can the shelf life t90% be calculated from the provided equation?

t90% = 0.105 / K25°C

What does the polarity of solvents affect in reactions?

The rate of reaction

How does the ionic strength affect the rate of reaction?

It increases the rate of reaction for neutral molecules

What is the relationship between the specific reaction rate (k) and the absolute temperature (T) according to Arrhenius equation?

k = Ae$-E_a/RT$

What factor is expected to affect the reaction velocity in addition to concentration, based on the provided text?

Molecularity

What is the relationship between reaction rate and temperature according to Collision Theory?

Reaction rate increases as temperature increases

What does the interfacial tension cause immiscible liquids to do?

Resist mixing

What type of intermolecular forces are reflected in the large surface tension values for mercury and water?

Hydrogen bonds

What chemical groups decrease the interfacial tension when present in a substance?

Groups capable of hydrogen bonding with water

What is the net effect on molecules at the surface of a liquid?

They experience an inward force toward the bulk

What is interfacial tension?

The force per unit area existing at the interface between two immiscible liquid phases

Why are interfacial tensions ordinarily less than surface tensions?

Because the adhesive forces between two liquid phases forming an interface are greater

What is the initial spreading coefficient when benzene is added to water?

10.1 dyne/cm

What does a negative final spreading coefficient indicate?

Formation of a lens by benzene on the surface of water

What phenomenon is observed when benzene and water become mutually saturated with each other?