aqueous sulfurous acid H2SO3 was made by dissolving 0.200 L of sulfur dioxide gas at 19 C and 745 mm Hg in water to yield 500.0 ml of solution. the acid solution required 12.9 ml of sodium hydroxide solution to reach the titration end point. what was the molarity of the sodium hydroxide solution?
SO2 + H2O ==> H2SO3
Use PV = nRT to determine the mols SO2. Don't forget T must be in Kelvin. Since the equation is a 1:1 ratio for SO2 to H2SO3, that will be the number of moles H2SO3.
Then for the titration. You don't say WHICH end point; I assume the NaOH titrates all of the H2SO3 (both H ions).
2NaOH + H2SO3 ==> Na2SO3 + 2H2O
moles H2SO3 = ??
moles NaOH is 2 x that.
Then M NaOH = moles NaOH/L NaOH.
To find the molarity of the sodium hydroxide (NaOH) solution, we need to use the balanced chemical equation for the reaction between sodium hydroxide and sulfurous acid:
H2SO3 + 2NaOH -> Na2SO3 + 2H2O
From the equation, we can determine that one mole of sulfurous acid reacts with two moles of sodium hydroxide. Therefore, the molar ratio is 1:2.
First, let's calculate the number of moles of sulfurous acid used. We can use the ideal gas law equation to convert the volume of sulfur dioxide gas to moles:
PV = nRT
Where:
P = pressure = 745 mmHg = 99.267 kPa
V = volume = 0.200 L
n = number of moles of sulfur dioxide gas
R = ideal gas constant = 8.314 J/(mol·K)
T = temperature in Kelvin = (19 + 273) K = 292 K
Rearranging the equation to solve for n:
n = PV / RT
n = (99.267 kPa * 0.200 L) / (8.314 J/(mol·K) * 292 K)
n ≈ 0.0134 mol
Since the molar ratio between sulfur dioxide and sulfurous acid is 1:1, the number of moles of sulfurous acid is also 0.0134 mol.
Next, we can calculate the molarity of the sulfurous acid solution. The molarity (M) is defined as moles of solute divided by volume of solution in liters:
M = moles of solute / volume of solution
M = 0.0134 mol / 0.500 L
M ≈ 0.0268 mol/L
Now, we know that the molar ratio between sulfurous acid and sodium hydroxide is 1:2. Therefore, the number of moles of sodium hydroxide used is twice the number of moles of sulfurous acid used:
Moles of NaOH = 2 * 0.0134 mol
Moles of NaOH = 0.0268 mol
Finally, we can calculate the molarity of the sodium hydroxide solution using the formula:
M = moles of solute / volume of solution
M = 0.0268 mol / 0.0129 L
M ≈ 2.08 mol/L
Therefore, the molarity of the sodium hydroxide solution is approximately 2.08 mol/L.
To find the molarity of the sodium hydroxide (NaOH) solution, we need to use the balanced chemical equation for the reaction between sulfurous acid (H2SO3) and sodium hydroxide.
The balanced chemical equation is:
H2SO3 + 2NaOH → Na2SO3 + 2H2O
From the equation, we can see that one mole of H2SO3 reacts with 2 moles of NaOH. Thus, the volume of the H2SO3 solution that reacted with NaOH can be used to determine the number of moles of NaOH.
Given:
Volume of NaOH solution = 12.9 mL = 0.0129 L
Now, we can calculate the number of moles of NaOH:
Moles of NaOH = Volume (in L) × Molarity
Moles of NaOH = 0.0129 L × Molarity
To determine the molarity of NaOH, we need the number of moles and the volume in the equation. However, we are missing the number of moles of NaOH at the endpoint.
To find the number of moles of NaOH at the endpoint, we need to use the concept of stoichiometry. Let's assume that all the sulfurous acid reacted with NaOH.
From the balanced chemical equation, we can see that one mole of H2SO3 reacts with 2 moles of NaOH. Therefore, the number of moles of NaOH at the endpoint will be half of the moles of H2SO3 present initially.
Now, we need to find the moles of H2SO3. To do that, we can use the ideal gas law.
Given:
Volume of sulfur dioxide gas (SO2) = 0.200 L
Pressure of SO2 = 745 mm Hg
Temperature = 19 °C = 292 K
We can use the ideal gas law equation to determine the number of moles of SO2:
PV = nRT
First, we need to convert the pressure to atm and the temperature to Kelvin:
Pressure of SO2 = 745 mm Hg = 0.9805 atm (using 1 atm = 760 mm Hg)
Temperature = 19 °C = 292 K
Now we can rearrange the ideal gas law equation to solve for moles (n):
n = PV / RT
n = (0.9805 atm) × (0.200 L) / (0.0821 L·atm/mol·K) × (292 K)
Calculate the moles of SO2.
Now that we know the initial moles of H2SO3, we can find the moles of NaOH at the endpoint by dividing the moles of H2SO3 by 2.
Once you have calculated the moles of NaOH at the endpoint, you can now determine the molarity of the NaOH solution:
Molarity of NaOH = Moles of NaOH at the endpoint / Volume of NaOH solution (in L)
Insert the calculated values for Moles of NaOH at the endpoint and Volume of NaOH solution to calculate the molarity of the NaOH solution.