Thursday

April 2, 2015

April 2, 2015

Posted by **Help** on Monday, March 15, 2010 at 6:17pm.

In a first order decomposition reaction, 50% of a compound decomposes in 10.5 minutes. What is the rate constant of the reaction?

The solution my professor gave says:

k = .693 / 10.5min

Where did the .693 come from?

Thanks

- Chemistry -
**DrBob222**, Monday, March 15, 2010 at 7:18pmThat is the natural logarithm of 2. You can do it this way.

Let's start with 100 atoms of something.

No = 100. Since it is 50% decomposed in 10.5 min, then 10.5 is the half-life and N at the end of that time will be 50.

So ln(No/N) = kt

ln(100/50) = k*t_{1/2}

ln(2) = k*t_{1/2}

0.693 = k*t_{1/2}and

k = 0.693/t_{1/2}

**Answer this Question**

**Related Questions**

Chemistry - In a first order decomposition reaction, 50% of a compound ...

Chemistry - What is the value of the rate constant for a reaction in which 75.0 ...

Chemistry - What is the value of the rate constant for a reaction in which 75.0 ...

Chemistry - a certain first order decomposition reaction has a half-life of 15.0...

Chemistry - A reaction is first order and it takes 324 minutes for the reaction ...

Half-Life - Can someone please show me a detailed solution to this problem? ...

Chemistry - Dinitrogen pentoxide, N2O5, decomposes by a first-order reaction. ...

Chemistry - The rate constant for the decomposition of gaseous azomethane, C2 ...

chemistry - how do you solve this problem? consider the reaction A->B the ...

Chemistry - i seriously do not understand the formula for this problem :( The ...