Complete the following table by calculating the missing entries. In each case indicate whether t

Complete the following table by calculating the missing...

Key Concepts

pH Scale

The pH scale is a quantitative measure of the acidity or basicity of a solution, ranging from 0 to 14. A pH value below 7 indicates an acidic solution, while a pH value above 7 indicates a basic solution, and a pH of 7 represents a neutral solution.

Acidic and Basic Solutions

An understanding of acidic and basic solutions is essential in acid-base chemistry. Acidic solutions have higher concentrations of hydrogen ions (H+), resulting in pH values below 7, whereas basic solutions have higher concentrations of hydroxide ions (OH-), leading to pH values above 7.

Logarithmic Calculations in pH Determination

Calculating pH often involves logarithmic functions, where pH is defined as the negative logarithm of the hydrogen ion concentration (pH = -log[H+]). This mathematical relationship helps simplify and manage the wide range of hydrogen ion concentrations encountered in aqueous solutions.

Water Ionization and the Ion Product Constant (Kw)

The ion product constant for water (Kw) is a critical concept in acid-base chemistry, representing the relationship between the concentrations of hydrogen ions and hydroxide ions in water (typically 1.0 x 10^-14 at 25°C). It is used to relate pH and pOH and to calculate one when the other is known.

Transcript

00:01 All right, today we'll be doing chapter 16, problem 36, completing the table, and we're going to be using the equations on the right side.

00:11 Ph is equal to the negative log of your h concentration.

00:15 Your h plus concentration is equal to 10 to the negative ph.

00:19 This also works face -versely for the p -o -h in the o -h concentrations.

00:23 Also, 14 is equal to your ph plus your p -o -h, and then your k -w is equal to your o -h times your h.

00:31 Your h plus concentrations.

00:35 So we're first going to be using our ph for row one, and we're going to be trying to find our p -o -h.

00:46 So we're going to be using the equation, 14 is equal to our ph plus our p -o -h.

00:52 And what we would be doing is just doing 14 minus our ph.

00:59 And when we do that, we should get 8 .75 for our first answer.

01:05 All right, so now that we have our ph and our poh, we can now find our h plus ion concentration as it's next in line.

01:17 And so to do our h -ion concentration, we're going to use the next equation, which is 10 to the negative ph.

01:25 And so we just do 10 to the negative 5 .25.

01:30 And when we plug that into our calculator, we should get 5 .6 times 10 to the negative 6.

01:42 All right.

01:43 Next, we're going to find our o -h concentration.

01:47 And we're going to use the same general equation that we just used.

01:51 Instead of our ph, we're going to put our p -o -h, which we just calculated.

01:57 There's 8 .75.

01:59 And when we plug that entire calculator, we go 1 .78 times 10 to the negative 9th.

02:08 All right.

02:09 So now, since we have that answer as well, we can now figure out if it is acidic.

02:14 Or basic.

02:16 And when we look at our ph scale, the acidity goes from zero.

02:21 And our basic is at 14 and usually neutral around 7.

02:28 So our ph is about 5 .25.

02:32 And so therefore it runs around the acidity area.

02:35 So our answer is acidic.

02:38 All right.

02:39 Now time to go into the next part, which is the second row.

02:46 So now we're given our p -o -h, and so now we have to find our ph.

02:51 We can still use that same equation we use in the first part, whereas our ph plus our p -o -h.

02:59 And so this time we were given our p -o -h, so all we had to do is 14 minus our 2 .02, which is our p -o -h, to get our p -h.

03:08 And in this case, it is 11 .98 when you plug it into your calculator...

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