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(LO 37,45) A reaction is 75% complete in 45.0 min. How long after its start will the reaction be 50% complete if it is (A) first

seropon [69]

Answer:

A) t = 22.5 min and B) t = 29.94 min

Explanation:

Initial concentration, [A]₀ = 100

Final concentration = 100 -75 = 25

Time = 45 min

A) First order reaction

ln[A] − ln[A]₀ = −kt

Solving for k;

ln[25] − ln[100] = - 45k

-1.386 = -45k

k = 0.0308 min-1

How long after its start will the reaction be 50% complete?

Initial concentration, [A]₀ = 100

Final concentration, [A] = 100 -50 = 50

Time = ?

ln[A] − ln[A]₀ = −kt

Solving for k;

ln[50] − ln[100] = - 0.0308 * t

-0.693 = -0.0308 * t

t = 22.5 min

B) Zero Order

[A] = [A]₀ − kt

Using the values from the initial reaction and solving for k, we have;

25 = 100 - k(45)

-75 = -45k

k = 1.67 M min-1

How long after its start will the reaction be 50% complete?

Initial concentration, [A]₀ = 100

Final concentration, [A] = 100 -50 = 50

Time = ?

[A] = [A]₀ − kt

50 = 100 - (1.67)t

-50 = - 1.67t

t = 29.94 min

3 0

3 years ago

Give the coordination number of the central metal ion in the following complex ions.

melomori [17]

Answer:

a). Coordination no. of $[Ni(en)_2(NH_3)_2]^2+$ = 6

b). Coordination no. of $[Fe(en)(ox)Cl_2]^2-$ = 6

Explanation:

Coordination number is defined as number of donar atoms bonded to the central atom of the complex ion.

a). Coordination no. of $[Ni(en)_2(NH_3)_2]^2+$ = 6

en or ethylenediamine is a bidentate ligand.

In bidentate ligand, two atoms directly bonded to the central atom.

NH3 is a unidentate ligand.

So, coordination no.= No. of bidentate ligand x 2 + No. of unidentate ligand

= $2\times 2 + 2 = 6$

b). Coordination no. of $[Fe(en)(ox)Cl_2]^2-$ = 6

Ethylenediamine (en) is a bidentate ligand.

oxalate ion (ox) is also a bidentate ligand.

Cl is a unidentate ligand

So, coordination no.= No. of bidentate ligand x 2 + No. of unidentate ligand

= $2\times 2 + 2 = 6$

8 0

3 years ago

The following diagram represents the potential energy for the reaction:

Sloan [31]

A is the answer I reckon

3 0

2 years ago

Read 2 more answers

What is 6421 in scientific notation

Lynna [10]

The scientific notation should specific the significant digits. So it to write like x.xx * 10 ^ x. So the answer is 6.421 * 10 ^3.

4 0

2 years ago

A stock phenolphthalein solution was prepared by dissolving 0.050 g in a total volume of 100.0 ml. You place one drop (0.050 ml)

devlian [24]

Answer:

the value of molar absorptivity is 229000 $M^{-1} cm^{-1}$

Explanation:

given data

phenol phthalein solution = 0.050 g

total volume = 100.0 ml

dilute = 100.0 ml

diluted sample = 0.18

solution

we get here concentration that is express as

concentration = ( mass of solute × 1000 ) ÷ ( molar mass of solute × volume of solution ) .............1

put here value

concentration = $\frac{0.050\times 1000}{318.32\times 100}$

concentration = 0.00157 M

and here dillution equation is express as

c1 × v1 = c2 × v2 .................2

here c1 and c2 is initial and final concentration

and v1 and v2 is initial and final volume

put here value

0.001571 × 0.050 = c2 × 100

c2 = 7.855 × $10^{-7}$ M

and

now we get molar by absorbance equation that is

A = E × C × l ................3

here A is absorbance and E is molar and c is absorptivity and l is path length

put here value

0.18 = E × 7.855 × $10^{-7}$ × 1

E = 229000 $M^{-1} cm^{-1}$

3 0

2 years ago