Chemical Kinetics

This is a Fill in the blanks Type Question as classified in NCERT Exemplar

Ans: Correct option A

Exothermic Reaction: Exothermic reaction is a chemical reaction in which the enthalpy change is negative, and energy is released in the form of light and heat.

As we all know, ΔH is negative.

Activation energy (forward reaction) – (backward reaction)

(Forward reaction) - E_a (backward reaction) 

The product's exothermic energy exceeds the activation energy of the reactants, therefore the correct answer is A, or graph 1, which depicts an exothermic reaction.

This is a Fill in the blanks Type Question as classified in NCERT Exemplar

Ans: Correct option C

Rate of Disappearance = $\frac{-1}{5}$ $\frac{\mathbf{\Delta }\left[\mathbf{B}\mathbf{r}\right]}{\mathbf{\Delta }}$   = - $\frac{\mathbf{\Delta }\left[\mathbf{B}\mathbf{r}{\mathbf{O}}_3\right]}{\mathbf{\Delta }\mathbf{t}}$ =  $\frac{-1}{6}$ $\frac{\mathbf{\Delta }\left[{\mathbf{H}}^{+}\right]}{\mathbf{\Delta }\mathbf{t}}$

$\frac{\mathbf{\Delta }\left[\mathbf{B}\mathbf{r}\right]}{\mathbf{\Delta }}$ = $\frac{5}{6}$ $\frac{\mathbf{\Delta }\left[{\mathbf{H}}^{+}\right]}{\mathbf{\Delta }\mathbf{t}}$

This is a Fill in the blanks Type Question as classified in NCERT Exemplar

Ans: Correct option  A

Because reactant concentrations fall as reactants are transformed to products, reaction rates decrease over time. When reactant concentrations are raised, reaction rates generally increase

This is a Fill in the blanks Type Question as classified in NCERT Exemplar

Ans: Correct option B

Reaction occurring at the smallest time interval is known as instantaneous rate of reaction. For e.g the instantaneous rate of reaction at 40s is the rate of reaction during a small interval of time close to 40s. Volume changes during a small-time interval close to the 40s.

Instantaneous rate can be determined graphically by drawing a tangent on the curve

Instantaneous reaction= $\frac{\mathrm{C}\mathrm{h}\mathrm{a}\mathrm{n}\mathrm{g}\mathrm{e}\mathrm{}\mathrm{i}\mathrm{n}\mathrm{}\mathrm{C}\mathrm{o}\mathrm{n}\mathrm{c}\mathrm{e}\mathrm{n}\mathrm{t}\mathrm{r}\mathrm{a}\mathrm{t}\mathrm{i}\mathrm{o}\mathrm{n}\mathrm{}}{\mathrm{C}\mathrm{h}\mathrm{a}\mathrm{n}\mathrm{g}\mathrm{e}\mathrm{}\mathrm{i}\mathrm{n}\mathrm{}\mathrm{t}\mathrm{i}\mathrm{m}\mathrm{e}}$

Option B is incorrect since the line travels through the graph but does not link to any of the Y axis lines. As a result, option B is incorrect.

This is a Fill in the blanks Type Question as classified in NCERT Exemplar

Ans: Correct option C

Option (c) is the only one of the four assertions that is incorrect. In rate law expression, the order of reaction is equal to the sum of the power of concentration of the reactants.

xA + yB→zC

r = k (A)^x (B)^y 

Order x + y

The order of the reactions can also be a fraction. In a balanced chemical equation, the order of reaction may or may not be equal to the total of the stoichiometric coefficients of the reactants.

This is a Fill in the blanks Type Question as classified in NCERT Exemplar

Ans: Correct option C

In the given graph V is the volume in the Y axis and time is in X axis

Zn + dil.HCl→ZnCl₂ + H₂↑

Average rate = 40s

Average rate of reaction = $\frac{\mathrm{C}\mathrm{h}\mathrm{a}\mathrm{n}\mathrm{g}\mathrm{e}\mathrm{}\mathrm{i}\mathrm{n}\mathrm{}\mathrm{C}\mathrm{o}\mathrm{n}\mathrm{c}\mathrm{e}\mathrm{n}\mathrm{t}\mathrm{r}\mathrm{a}\mathrm{t}\mathrm{i}\mathrm{o}\mathrm{n}\mathrm{}\mathrm{o}\mathrm{f}\mathrm{}{\mathrm{H}}_2}{\mathrm{C}\mathrm{h}\mathrm{a}\mathrm{n}\mathrm{g}\mathrm{e}\mathrm{}\mathrm{i}\mathrm{n}\mathrm{}\mathrm{t}\mathrm{i}\mathrm{m}\mathrm{e}}$

$\frac{\mathrm{F}\mathrm{i}\mathrm{n}\mathrm{a}\mathrm{l}\mathrm{}\mathrm{C}\mathrm{o}\mathrm{n}\mathrm{c}\mathrm{e}\mathrm{n}\mathrm{t}\mathrm{r}\mathrm{a}\mathrm{t}\mathrm{i}\mathrm{o}\mathrm{n}-\mathrm{I}\mathrm{n}\mathrm{i}\mathrm{t}\mathrm{i}\mathrm{a}\mathrm{l}\mathrm{}\mathrm{C}\mathrm{o}\mathrm{n}\mathrm{c}\mathrm{e}\mathrm{n}\mathrm{t}\mathrm{r}\mathrm{a}\mathrm{t}\mathrm{i}\mathrm{o}\mathrm{n}}{\mathrm{F}\mathrm{i}\mathrm{n}\mathrm{a}\mathrm{l}\mathrm{}\mathrm{t}\mathrm{i}\mathrm{m}\mathrm{e}-\mathrm{}\mathrm{I}\mathrm{n}\mathrm{i}\mathrm{t}\mathrm{i}\mathrm{a}\mathrm{l}\mathrm{}\mathrm{T}\mathrm{i}\mathrm{m}\mathrm{e}}$

Analyzing the graph line where time and volume intersect. 

$\frac{{\mathrm{V}}_3-0}{40-0}$

$\frac{{\mathrm{V}}_3}{40}$

This is a Fill in the blanks Type Question as classified in NCERT Exemplar

Ans: Correct option D

k = Ae -    $\frac{\mathbf{}\mathbf{E}\mathbf{a}}{\mathbf{R}\mathbf{T}}$             

From this equation

Kα $\frac{1}{\mathrm{E}\mathrm{a}}$

When Activation energy Ea decreases, rate constant k

 increases.

Hence, Rate constant increases exponentially with decreasing activation energy and increasing temperature. 

This is a Fill in the blanks Type Question as classified in NCERT Exemplar

Ans: Correct option A

Arrhenius equation Ae -   $\frac{\mathbf{}\mathbf{E}\mathbf{a}}{\mathbf{R}\mathbf{T}}$

K = rate constant

A= frequency factor

Ea= Activation Energy

R= gas constant

T= temperature

ln k = lnA - $\frac{\mathbf{E}\mathbf{a}}{\mathbf{R}\mathbf{T}}$

When the temperature rises, ln falls.

∴ ln kv/s $\frac{1}{\mathbf{T}}\mathrm{}$ , is a negative slope.

ln A is intercepted by k, and its magnitude decreases with time.

∴ Negative slope is obtained.

When compared to the other possibilities, T is increasing over time, which is incorrect.

ln k =  $\frac{-\mathbf{E}\mathbf{a}}{\mathbf{R}}$ $\frac{1}{\mathbf{T}}\mathbf{}$  + lnA

This is a Fill in the blanks Type Question as classified in NCERT Exemplar

Ans: Correct option B

Given:  

A (g) → B (g) + C (g) 

p_i= Initial pressure

(Time) t = 0

A (g) → B (g) + C (g) 

p_i        →0atm + 0atm

t, (p_i - x)atm

p_t = (p_i - x)atm + x + x = p_i + x

p_A = (p_i - x)

The value of x changes when it is substituted.

p_A = p_i - (p_t - p_i) = 2p_i - p_t

K =  $\frac{2.303}{\mathrm{t}}$ log $\frac{{\mathrm{p}}_{\mathrm{i}}}{2{\mathrm{p}}_{\mathrm{i}}-{\mathrm{p}}_{\mathrm{t}}}$