Chemistry, 31.07.2019 20:30 YODIIZ6590

If the rate constant for the decomposition of n2o5 is 6.2 × 10−4/min, what is the half-life? (the rate law is first order in n2o5.) how long would it take for the concen- tration of n2o5 to decrease to 25% of its initial value? to 6.25% of its initial value?

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half life = 1.1*10^3min , 2.24*10^3min are taken for the concentration to decrease to 25% and 4.48*10^3min for the concentration to decrease to 6.25% .

Explanation: The given information says, the reaction is first order with respect to N_2O_5 . For first order reaction, rate constant and half life are related to each other as:

half life = $\frac{0.693}{k}$

(where k stands for rate constant)

Value of k is given as 6.2*10^-^4min^-^1

half life = $\frac{0.693}{6.2*10^-^4min^-^1}$

half life = 1117.74 min or 1.1*10^3min

Let's say the initial concentration is 100. It asks to calculate the time taken to decrease the concentration to 25% which will be 25 as we have taken the initial concentration 100.

The equation that we use is:

lnA=lnA_0-kt

Where, A_0 is initial and A is remaining concentration or amounts. k is rate constant and t is the time. Let's plug in the values and do calculations for t.

ln25=ln100-6.2*10^-^4min^-^1*t

3.22=4.61-6.2*10^-^4min^-^1*t

3.22-4.61=-6.2*10^-^4min^-^1*t

-1.39=-6.2*10^-^4min^-^1*t

$t=\frac{1.39}{6.2*10*^-^4min^-^1}$

t = 2241.94 min or 2.24*10^3min

We can calculate the time when the concentration decreases to 6.25% of its initial value same as we did for the above.

ln6.25=ln100-6.2*10^-^4min^-^1*t

1.83=4.61-6.2*10^-^4min^-^1*t

1.83-4.61=-6.2*10^-^4min^-^1*t

-2.78=-6.2*10^-^4min^-^1*t

$t=\frac{2.78}{6.2*10*^-^4min^-^1}$

t = 4483.87 min or 4.48*10^3min

So, the answers for all the three parts are: half life = 1.1*10^3min , 2.24*10^3min are taken for the concentration to decrease to 25% and 4.48*10^3min for the concentration to decrease to 6.25% .

Answer from: Quest

distance, luminosity, brightness, radius, chemical composition, and temperature

Answer from: Quest

the balanced equation for reaction of ca metal with o2 to produce cao is as below

2 ca+ o2→ 2 cao2

explanation

the reaction is balanced since the number of atoms in reactant side is equal to number of atoms in product side. for example they are 2 atom of ca in reactant side and 2 atoms of ca in the product side.

the process is a meet the requirement of redox reaction because : calcium is oxidized from oxidation state 0 to 2+ while oxygen is reduced from oxidation state 0 to 2-

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