hELP PLEASE.............?

Question

Find the pH factor of a substance of your choice. Is this substance acidic or basic? Why?
Using this pH, show how to find the hydrogen ion content of the substance using the formula. Round to 10 decimal places or write your answer using scientific notation. Include units on your answer.

Answer 1

The only help you need is learning how to do your own work. What don't you understand about this assignment that we can help you with?

Answer 2

"pH" is defined as the negative log of the hydrogen ion concentration of a solution. Let's define our terms:

"negative" = Not just "less than zero" in this case. It has a curious effect on logarithms. The logarithm of anything less than "1" is a negative number. To further complicate things, there are no logarithms of actual negative numbers. Negative logs are therefore any numbers greater than zero and less than 1.

"Log" = "logarithm". It is a mathematical means of writing a number in terms of another number raised to some power. "Powers" are the number of times a number is multiplied by itself repeatedly. For example, 10*10*10 = 1000. Therefore 1000 happens to be 10 raised to the third power. The logarithm of 1000 is therefore "3". Of course, numbers can also be raised to fractional powers as well. This makes it possible to describe any positive number greater than zero as 10 raised to some power. The power it is raised to is then the logarithm of that number.

"Hydrogen ion" = these subatomic particles are the basis of acidity. They are in fact naked protons. Ordinarily hydrogen atoms have a positive proton and a negative electron. If some acid molecule keeps the electron, the hydrogen is left as a single proton with a positive charge. This proton can then get its electron back from some other substance. This is how acids affect things chemically. Think of acids as "electron strippers".

"concentration" = chemists equate this to a cretain number of particles dissolved in a set volume of liquid. All chemistry is metric, so the volume is 1 liter, about a quart. Chemists use the "mole" as a basis of counting particles. It is 6 with 23 zeros following it. A huge number, but atoms are very small and weigh practically nothing. Only large numbers of them are significant enough to measure, hence the concept of the "mole" - and hence the definition of concentartion expressed in "moles" per "liter".

//////////////////////// and here's how it works!

Water is H2O, two hydrogens and a single oxygen. The three atoms stay together, but every now and then, one of them separates. The equation is:

H2O -> H(+) + OH(-)

Water is therefore an acid because of the hydrogen ions, but also a base because of the (-OH) hydroxyl ion. Everyone ought to know acids and bases cancel one another out and this is just what happens with pure water. There are exactly as many hydrogen ions as hydroxyl ions. The water is then neither an acid nor a base. It is "neutral".

Everyone ought to also know a pH of "7" is neutral. In terms of pH, this means we are expressing the hydrogen ion concentration terms of a negative logarithm. Now, since "7" is positive, it means the logarith itself is negative. This in turn means the concentration is a number less than one. In fact it is 0.0000001 or around a tenth of a part per million. This is the ordinary concentration of hydrogen ions in neutral water.

Now, this changes if some acid is added. The hydrogen ions from the acid didn't come from the water of course, so they accumulate. Now there are more than 0.1 parts per million. Say we increased the number of them to exactly 1 part in a million. That's one hydrogen ions to a million water molecules. The log of this concentration would be -6 and the negative log would be 6. This is why a pH value less than 7 is concidered "acid".

Of course, we can work in the opposite direction. If a base is added, it supplies negative hydroxyl ions. These then decrease the number of hydrogen ions by combining with them to form water. As the concentration gets smaller, the log becomes a greater and greater negative number. The pH is therefore now a number larger than 7. This is why a pH value greater than 7 is concidered alkaline.

There are limits to the scale. A pH of zero means there are as many hydrogen ions as there are water molecules. In other words the concentration is 1.0 exactly. Another fact about logarithms is the log of 1 is zero. In other words, any number raised to the zero "power" is equal to 1. The scale increases to 14. This means there is a 0.00000000000001 moles/liter hydrogen ion concentration, and no matter how much more base is added, it can't get less than this. Therefore, the pH scale runs from 0 to 14.