50.0 mL of an HCl solution with a pH of 3.5
neutralizes 200.0 mL of a Ca(OH)2 solution.
What is the molarity of the Ca(OH)2 solu-
tion?
Well, well, well! Looks like we have a classic neutralization reaction going on here. Let's do some calculations and see what we get!
First, we need to know the molarity of the HCl solution. The pH of 3.5 doesn't directly give us the concentration, but we can use it to find the concentration of H+ ions. pH is equal to the negative logarithm of the concentration of H+ ions, so we have 10^(-3.5) mol/L.
Now, let's focus on the neutralization reaction. The balanced equation for the reaction is:
2HCl + Ca(OH)2 → CaCl2 + 2H2O
From the equation, we can see that it takes 2 moles of HCl to neutralize 1 mole of Ca(OH)2. So, using the concentration of HCl and its volume (50.0 mL = 0.0500 L), we can calculate the number of moles of HCl:
moles of HCl = concentration of HCl × volume of HCl
= 10^(-3.5) mol/L × 0.0500 L
Now, since 2 moles of HCl neutralize 1 mole of Ca(OH)2, the number of moles of Ca(OH)2 can be found by halving the number of moles of HCl:
moles of Ca(OH)2 = moles of HCl / 2
Finally, we can find the molarity of the Ca(OH)2 solution by dividing the number of moles of Ca(OH)2 by its volume (200.0 mL = 0.200 L):
molarity of Ca(OH)2 solution = moles of Ca(OH)2 / volume of Ca(OH)2 solution
= (moles of HCl / 2) / 0.200 L
Now, let's calculate that and see what we get! *Calculating with dramatic clown music in the background*
To solve this problem, we need to use the concept of stoichiometry to find the molarity of the Ca(OH)2 solution.
Step 1: Find the number of moles of HCl in the 50.0 mL solution.
First, convert the pH to the concentration of H+ ions in the HCl solution.
pH = -log[H+]
3.5 = -log[H+]
H+ = 10^(-3.5)
[H+] = 3.16 x 10^(-4) mol/L
Now, find the number of moles of HCl in the 50.0 mL solution:
moles of HCl = concentration x volume
moles of HCl = (3.16 x 10^(-4) mol/L) x (50.0 mL / 1000 mL/L)
moles of HCl = 1.58 x 10^(-5) mol
Step 2: Write the balanced chemical equation for the neutralization reaction between HCl and Ca(OH)2.
2HCl(aq) + Ca(OH)2(aq) → CaCl2(aq) + 2H2O(l)
From the equation, we can see that 2 moles of HCl react with 1 mole of Ca(OH)2.
Step 3: Find the number of moles of Ca(OH)2 in the Ca(OH)2 solution.
Since the mole ratio between HCl and Ca(OH)2 is 2:1, the number of moles of Ca(OH)2 is half that of the HCl:
moles of Ca(OH)2 = (1.58 x 10^(-5) mol) / 2
moles of Ca(OH)2 = 7.9 x 10^(-6) mol
Step 4: Find the molarity of the Ca(OH)2 solution.
Molarity = moles / volume (in liters)
Molarity = (7.9 x 10^(-6) mol) / (200.0 mL / 1000 mL/L)
Molarity = 3.95 x 10^(-2) mol/L
Therefore, the molarity of the Ca(OH)2 solution is 3.95 x 10^(-2) mol/L.
To find the molarity of the Ca(OH)2 solution, we need to use the concept of neutralization reactions.
First, let's determine the moles of HCl using the given information. We know that the pH of the HCl solution is 3.5. pH is a measure of the hydrogen ion concentration in a solution, and since HCl is a strong acid, it dissociates completely in water to give H+ ions. The concentration of H+ ions can be calculated using the equation:
pH = -log[H+]
From the given pH of 3.5, we can determine the concentration of H+ ions:
[H+] = 10^(-pH)
[H+] = 10^(-3.5)
Now, we can calculate the moles of HCl using its volume and concentration:
Moles of HCl = Concentration * Volume
Moles of HCl = [H+] * Volume
Given that the volume of the HCl solution is 50.0 mL and [H+] = 10^(-3.5), we can substitute these values and calculate the moles of HCl.
Next, let's determine the moles of Ca(OH)2. Since HCl and Ca(OH)2 react in a 1:2 ratio, the number of moles of Ca(OH)2 will be twice the moles of HCl.
Now, let's determine the molarity of the Ca(OH)2 solution. Molarity is defined as moles of solute divided by the volume of the solution in liters.
Molarity = Moles of Ca(OH)2 / Volume of Ca(OH)2
Given that the volume of the Ca(OH)2 solution is 200.0 mL, we need to convert it to liters by dividing by 1000.
Once we have the moles of Ca(OH)2 and the volume in liters, we can substitute these values into the molarity formula and calculate the molarity of the Ca(OH)2 solution.
2HCl + Ca(OH)2 ==> CaCl2 + 2H2O
pH 3.5 means (HCl) = 3.16E-4 but you should confirm and be more accurate.
mols Ca(OH)2 = 2*mols HCl
M Ca(OH)2 = mols Ca(OH)2/L Ca(OH)2