The flask shown here contains 10.0 mL of HCl and a few drops of phenolphthalein indicator. The buret contains 0.270 M NaOH.
What volume of NaOH is needed to reach the end point of the titration?
What was the initial concentration of HCl?
duplicate post.
To find the volume of NaOH needed to reach the end point of the titration, you need to use the balanced chemical equation for the reaction between HCl and NaOH.
The balanced equation for this reaction is:
HCl + NaOH -> NaCl + H2O
From the equation, you can see that the ratio of moles of HCl to NaOH is 1:1.
Since you know the initial volume of HCl is 10.0 mL and the concentration of NaOH is 0.270 M, you can use the concept of stoichiometry to determine the volume of NaOH needed to reach the end point.
Here are the steps to calculate the volume of NaOH:
1. Convert the volume of HCl from milliliters to liters:
10.0 mL = 10.0 mL/1000 mL/L = 0.010 L
2. Use the equation C1V1 = C2V2 to determine the volume of NaOH:
C1V1 = C2V2
(1 mol/L)(0.010 L) = (0.270 mol/L)(V2)
V2 = (0.010 L)(0.270 mol/L) / (1 mol/L)
V2 = 0.0027 L or 2.7 mL
Therefore, the volume of NaOH needed to reach the end point of the titration is 2.7 mL.
Now, let's calculate the initial concentration of HCl.
Since the balanced equation for the reaction is 1:1 between HCl and NaOH, the moles of HCl should be equal to the moles of NaOH at the end point of the titration.
1 mole of NaOH reacts with 1 mole of HCl.
From the previous calculation, we found that the volume of NaOH needed to reach the end point is 2.7 mL.
Now, we need to convert the volume of NaOH to moles using its molarity.
3. Convert the volume of NaOH from milliliters to liters:
2.7 mL = 2.7 mL/1000 mL/L = 0.0027 L
4. Use the equation M = moles/volume to calculate the initial concentration of HCl:
M(HCl) = moles(HCl) / volume(HCl)
M(HCl) = moles(NaOH) / volume(HCl)
M(HCl) = (0.270 mol/L)(0.0027 L) / (0.010 L)
M(HCl) = 0.0729 M
Therefore, the initial concentration of HCl is 0.0729 M.