At room temperature (25°C), 45 mL of a 0.002 M acid solution reacts with 30 mL of a

NaOH (aq) solution (pH = 11.95), determine (through calculations) whether the acid
is phosphoric acid (H3PO4), acetic acid (CH3COOH), or carbonic acid (H2CO3).

pH 11.95 means pOH = 2.05

pOH = -log(OH^-)
(OH^-) = 0.00891
0.00891 x 30 mL = about 0.27 (Note: Calculations give this as 0.267 but I've rounded to 0.27 because you're allowed only two significant figures.)
mmols acid = 45 x 0.002 = 0.09

CH3COOH + NaOH ==> CH3COONa + H2O
0.09 requires 0.09 but we used 0.27. Can't be CH3COOH.

H2CO3 + 2NaOH ==> Na2CO3 + 2H2O
0.09 requires 0.18 but we used 0.27. Can't be H2CO3.

H3PO4 + 3NaOH ==> Na3PO4 + 3H2O
0.09 requires 0.27 and that's what we used. Must be H3PO4.

Thank you so much! Not it makes sense!

Well, pHew, that's quite a chemistry question! But don't worry, I'm here to clown around and help you find the answer.

To solve this little puzzle, we need to use some Stoichiometry and find the moles of acid and moles of base. Let's start with the acid.

Given that the volume of the acid solution is 45 mL, and the concentration is 0.002 M, we can calculate the moles of acid by multiplying the concentration by the volume:

Moles of acid = 0.002 M * 0.045 L (since 45 mL is equal to 0.045 L)

Now, let's move on to the base. The pH of the NaOH solution is given as 11.95. To find the concentration, we need to convert the pH to a concentration of hydroxide ions (OH-).

Since pH is defined as the negative logarithm of the hydrogen ion concentration (pH = -log[H+]), we can find the concentration of hydroxide ions by taking the exponent of the negative value of the pH:

[OH-] = 10^-(pH)

So, the concentration of hydroxide ions is: [OH-] = 10^-(11.95)

Now, the concentration of the NaOH solution is equal to the concentration of hydroxide ions, so we can calculate the moles of NaOH using the concentration and volume given:

Moles of NaOH = [OH-] * Volume of NaOH solution

Given that the volume of the NaOH solution is 30 mL, we need to convert it to liters: Volume of NaOH solution = 0.030 L

Moles of NaOH = [OH-] * 0.030 L

Now that we know the moles of the acid (let's call it MA) and the moles of NaOH (let's call it MNaOH), we can figure out the ratio between them. This will give us a clue about which acid is being used.

For phosphoric acid (H3PO4), the reaction with sodium hydroxide (NaOH) proceeds as follows:

H3PO4 + 3NaOH → Na3PO4 + 3H2O

So, the ratio between MA and MNaOH should be 1:3.

For acetic acid (CH3COOH), the reaction with sodium hydroxide (NaOH) goes like this:

CH3COOH + NaOH → CH3COONa + H2O

Therefore, the ratio between MA and MNaOH should be 1:1.

And for carbonic acid (H2CO3), the equation with NaOH looks like this:

H2CO3 + 2NaOH → Na2CO3 + 2H2O

Hence, the appropriate ratio between MA and MNaOH should be 1:2.

Now, calculate the ratios for each acid and see which one matches the calculated MA to MNaOH ratio. If the ratio is 1:3, it's phosphoric acid. If it's 1:1, it's acetic acid. And if it's 1:2, it's carbonic acid.

Remember, these calculations will help you clown around with the right answer!

To determine which acid is reacting, we need to use the balanced chemical equation for the reaction between acids and bases. Then, we can compare the stoichiometry from the equation with the given data to find the identity of the acid.

The balanced chemical equation for the reaction of an acid (HA) with sodium hydroxide (NaOH) is:

HA + NaOH → NaA + H2O

In this reaction, the acid donates a proton (H+) to the hydroxide ion (OH-) of the base to form water.

Now, let's consider the reaction between the acid and NaOH in the given data:

45 mL of 0.002 M acid solution reacts with 30 mL of NaOH solution.

We need to find the ratio of acid to NaOH based on their volumes and concentrations. To compare the reactants, we can use the concept of moles.

Step 1: Calculate the number of moles of NaOH.
Given:
Volume of NaOH solution (V) = 30 mL
pH of NaOH solution = 11.95

Since the pH of NaOH is given, we can use it to find the hydroxide ion concentration (OH-) using the formula:

[OH-] = 10^(-pOH)

pOH = 14 - pH
pOH = 14 - 11.95
pOH ≈ 2.05

[OH-] ≈ 10^(-2.05) M

As NaOH is a strong base, it completely dissociates in water, so the concentration of hydroxide ions is equal to the concentration of NaOH:

[NaOH] = [OH-] ≈ 10^(-2.05) M

Now, let's calculate the number of moles of NaOH:

Number of moles of NaOH = [NaOH] * Volume of NaOH solution
Number of moles of NaOH = 10^(-2.05) M * 0.030 L

Step 2: Calculate the number of moles of acid.
Given:
Volume of acid solution (V) = 45 mL
Concentration of acid solution (C) = 0.002 M

Number of moles of acid = Concentration of acid * Volume of acid solution
Number of moles of acid = 0.002 M * 0.045 L

Step 3: Determine the acid.

Now we can compare the number of moles of acid and NaOH based on the balanced chemical equation:

mole ratio of acid to NaOH = coefficient of NaOH / coefficient of acid

From the balanced chemical equation,
coefficient of NaOH = 1 (since it is 1 NaOH)
coefficient of acid = ?

To determine the coefficient of acid in the balanced equation, we need to look at the number of moles of acid and NaOH. If the mole ratio is 1:1, that means both have the same coefficient in the balanced equation.

Therefore, if the number of moles of acid and NaOH are equal, we can determine the acid based on their identity.

If the number of moles of acid is less than the number of moles of NaOH, it means the coefficient of acid in the balanced equation is smaller than 1. If the number of moles of acid is greater, it means the coefficient of acid in the balanced equation is greater than 1.

Comparing the two calculated number of moles, you can determine which acid is reacting in the given reaction.

To determine the identity of the acid, we need to calculate the number of moles of acid and compare it to the number of moles of NaOH used in the reaction.

Step 1: Calculate the number of moles of NaOH:
To do this, we'll use the concentration and volume of the NaOH solution.

Moles of NaOH = concentration × volume
Moles of NaOH = 10^(-pH) × volume

Moles of NaOH = 10^(-11.95) × 30 mL
Moles of NaOH = 10^(-11.95) × 0.03 L (since 1 mL = 0.001 L)
Moles of NaOH = 0.518 × 10^(-11) mol

Step 2: Calculate the number of moles of acid:
To do this, we'll use the concentration and volume of the acid solution.

Moles of acid = concentration × volume
Moles of acid = 0.002 mol/L × 45 mL
Moles of acid = 0.002 × 0.045 L
Moles of acid = 9 × 10^(-5) mol

Step 3: Compare the number of moles of acid and NaOH:
Now, we'll compare the number of moles of NaOH and the acid to determine the acid's identity:

Since the number of moles of NaOH (0.518 × 10^(-11) mol) is significantly smaller than the number of moles of acid (9 × 10^(-5) mol), we can conclude that the acid is not phosphoric acid (H3PO4) or carbonic acid (H2CO3).

Therefore, the acid is most likely acetic acid (CH3COOH).