Calculate the concentration of a 50.0mL sample of HBr acid, which was titrated with 37.7 mL of 0.57 M NaOH base.
Why is an overshot endpoint not a good titration?
Write the equation.
HBr + NaOH ==> NaBr + HOH
mols NaOH = M x L = ??
mols HBr = mols NaOH (see the equation is 1!1 ratiio).
Mols HBr = M x L.
You have mols from above, you have L, calculate molarity.
To calculate the concentration of the HBr acid, we can use the concept of stoichiometry. In a chemical reaction between an acid and a base, the balanced equation represents a 1:1 ratio between the acid and the base. Therefore, the moles of the acid can be determined based on the moles of the base used in the reaction.
To calculate the concentration, we can follow these steps:
Step 1: Determine the number of moles of NaOH used.
Given that the volume of NaOH used is 37.7 mL and the concentration of NaOH is 0.57 M, we can use the formula:
moles of NaOH = volume (L) x concentration (M) = 0.0377 L x 0.57 M = 0.021489 moles
Step 2: Write the balanced equation for the reaction between HBr and NaOH.
HBr + NaOH → NaBr + H2O
Step 3: Use the balanced equation to determine the number of moles of HBr.
Since the balanced equation shows a 1:1 ratio between HBr and NaOH, the moles of HBr are also 0.021489 moles.
Step 4: Calculate the concentration of HBr.
The concentration is given by the formula:
concentration (M) = moles / volume (L)
Given that the volume of the HBr solution is 50.0 mL (0.0500 L), we can calculate the concentration:
concentration of HBr = 0.021489 moles / 0.0500 L = 0.42978 M
Therefore, the concentration of the 50.0 mL sample of HBr acid is 0.42978 M.
Now, let's move on to your second question.
An overshot endpoint is not desirable in titration because it indicates that more titrant (in this case, the NaOH base) has been added than needed to reach the equivalence point (the point at which the reactants are stoichiometrically balanced). This means the reaction has gone beyond the required point, resulting in excess reactants.
The overshot endpoint can occur due to various reasons, such as human error in observing color changes or adding the titrant too quickly. It can lead to inaccurate results and affect the precision and accuracy of the titration.
It is important to accurately measure and add the titrant until the true endpoint of the reaction is reached, where the reaction between the acid and the base is complete. This allows for precise determination of the concentration of the analyte being titrated.
To avoid an overshot endpoint, titration should be performed carefully, following proper techniques such as adding the titrant gradually near the endpoint and observing any indicators or other signals that show the reaction has completed. This ensures accurate and reliable results.