+0  
 
0
95
3
avatar

what is 7.2 divided by a negative log

Guest Mar 15, 2017
Sort: 

3+0 Answers

 #1
avatar+75287 
0

7.2  = - log (H).....multiply both sides by  -1

 

-7.2  = log (H)     and  we can write

 

10-7.2  = H ≈   6.3 x 10-8

 

 

cool cool cool

CPhill  Mar 15, 2017
 #2
avatar
0

log, or logarithm, is an operation.  It is in the same category as a multiplication or addition.  Logistically, the question you asked doesn't really make sense as it would be in the same line as asking, "what is 7.2 divided by a multiplication sign?"

 

 What we're looking for here is the concentration of protons (H+) or more accurately hydronium ions (H3O+).  A pH of 7.2 says that your solution is 10^(-7.2) molar H3O+.  A pH of 13.1 would mean your solution is 10^(-13.1) molar H3O+.  

 

Logarithms are operators saying "to what number must your base be raised to achieve a number?"  For instance, another way of writing 10^x = 1000 is writing log10(1000) = x, where x = 3.  Exponentials and logarithms are like additiion/subtraction or multiplication/division.  They are inverse operators.

 

So, that means in order to know the concentration of H+ or H3O+, we can multiply both sides by negative one and exponentiate 10^(-7.2) to learn the molarity.

 

 

If anything I said was unclear, please let me know.

Cheers.

Guest Mar 15, 2017
 #3
avatar
0

My teacher confirmed the answer was 6.3*10^-8 Thanks

Guest Mar 15, 2017

12 Online Users

avatar
We use cookies to personalise content and ads, to provide social media features and to analyse our traffic. We also share information about your use of our site with our social media, advertising and analytics partners.  See details