Calculate the pH of each of the following strong acid solutions: (𝐚) 0.0178 M HNO3,(𝐛) 0.500 g

Calculate the pH of each of the following strong acid...

Calculate the pH of each of the following strong acid solutions: $(\mathbf{a}) 0.0178 \mathrm{M} \mathrm{HNO}_{3},(\mathbf{b}) 0.500 \mathrm{~g}$ of $\mathrm{HClO}_{3}$ in $5.00 \mathrm{~L}$ of solution, $(\mathbf{c}) 5.00 \mathrm{~mL}$ of $2.00 \mathrm{M} \mathrm{HCl}$ diluted to $0.500 \mathrm{~L}$, (d) a mixture formed by adding $75.0 \mathrm{~mL}$ of $0.010 \mathrm{M} \mathrm{HCl}$ to $125 \mathrm{~mL}$ of $0.020 \mathrm{M} \mathrm{HBr}$.

Calculate the pH of each of the following strong acid solutions: $(\mathbf{a}) 0.0178 \mathrm{M} \mathrm{HNO}_{3},(\mathbf{b}) 0.500 \mathrm{~g}$ of $\mathrm{HClO}_{3}$ in $5.00 \mathrm{~L}$
of solution, $(\mathbf{c}) 5.00 \mathrm{~mL}$ of $2.00 \mathrm{M} \mathrm{HCl}$ diluted to $0.500 \mathrm{~L}$, (d) a mixture formed by adding $75.0 \mathrm{~mL}$ of $0.010 \mathrm{M} \mathrm{HCl}$ to $125 \mathrm{~mL}$ of $0.020 \mathrm{M} \mathrm{HBr}$.

Key Concepts

pH Calculation

The pH of a solution is defined as the negative logarithm (base 10) of the hydrogen ion concentration. This concept is central to acid-base chemistry and provides a scale (typically from 0 to 14) for measuring how acidic or basic a solution is. For solutions where the concentration of hydrogen ions is known, the pH can be directly calculated using the formula pH = -log[H+].

Strong Acids

Strong acids are substances that dissociate completely in aqueous solution, meaning that every molecule of acid contributes one or more hydrogen ions. This complete ionization simplifies the pH calculation because the concentration of hydrogen ions is directly equal to the initial concentration of the acid (considering the stoichiometry of dissociation).

Molarity and Concentration

Molarity, defined as moles of solute per liter of solution, is a fundamental concept for preparing and calculating the concentrations of solutions. It is crucial for pH calculations, as determining the number of moles from mass (when given the molar mass) or volume and concentration (when dealing with liquid solutions) allows for the accurate determination of the hydrogen ion concentration.

Dilution

Dilution refers to the process of reducing the concentration of a substance in solution, typically by adding more solvent. The concept is governed by the relation C?V? = C?V?, where the initial concentration and volume determine the final concentration after the addition of solvent. This principle is essential when dealing with acid solutions that have been diluted before pH measurement.

Solution Mixtures

When combining multiple solutions, especially acids, the overall hydrogen ion concentration is found by summing the total moles of hydrogen ions contributed by each solution and then dividing by the total volume of the mixture. This approach ensures that the pH reflects the combined effect of all acidic components present in the mixed solution.

Transcript

0:00 All right.

00:01 We're going to be doing chapter 16, question number 44 from chemistry, the central science.

00:08 And the question is asking us to calculate ph over the following strong acid solutions when they give us different conditions.

00:16 But the first one is giving us a concentration of 0 .067 molar of hno3.

00:28 And so to find our ph of this, we know ph is equal to the negative log of our h concentration, which is given above.

00:41 And so we just do the negative log of our 0 .0167.

00:49 And when we plug that into our calculator, we get 1 .78 for our ph.

00:55 So that is going to be our answer for a.

00:59 So for b, we are given 0 .225 grams of h .c .o3.

01:12 And we dissolve it in two liters of a solution.

01:18 So the first thing we have to do first is find the molarity, which is moles over liters.

01:25 So we need to figure out how many moles of hcl -o -3 we have.

01:31 To find the moles, we take the amount of grams that we have and divide it by the molecular weight of h -c -l -3.

01:42 H -c -l -o -3.

01:43 And the molecular weight of h -c -l -o -3 is 1 times the molecular weight of h, plus 1 times the molecular weight of 8 means cl, plus 3 times the molecular weight of oxygen.

02:02 So we'll have 1 .01 plus 35, plus 3 times 16.

02:12 And our molecular weight is going to be 84 .5.

02:24 So we then plug it into here to get our moles of hcl3.

02:35 And when we plug that into our calculator, we get 0 .00266 of h.

02:56 C .l .3.

02:59 Now we have our moles and we know the amount of liters.

03:02 So to get our molarity, we're just going to do 0 .00266 divided by 2 liters.

03:13 And we get the concentration of 0 .00133.

03:21 Now, since we have our concentration of our sample, we can now just use the equation that we used a little bit earlier, doing the ph is equal to the negative log of our h.

03:32 Plus ion concentration.

03:36 And when we plug that into our calculator, we get a ph of 2 .88.

03:48 Alrighty.

03:49 So now we're going to go on to part c of this question.

03:57 And it is saying that we have 15 milliliters of a one molar hcl solution, but then we dilute it into 15.

04:09 500 milliliters or 0 .5 liters, sorry...

Please give Ace some feedback