if a student doing an experiment failed to dry the KHP before using it to standarize the NaOH solution.
A) Would her calculated molarity of the NaOH solution probably be too hight or too Low?
too low?
If the student did not dry the KHP (potassium hydrogen phthalate) before using it to standardize the NaOH (sodium hydroxide) solution, it implies that there could be moisture in the KHP. This moisture would cause the KHP to weigh more than it should, thus leading to a higher measured mass of KHP while performing the experiment. As a result, the calculated molarity of the NaOH solution would be higher than it should be.
To explain why this happens, it's important to understand the principle of titration. In this case, the KHP is used as the primary standard to determine the concentration of the NaOH solution. The balanced chemical equation for the reaction between KHP and NaOH is:
KHP + NaOH → KNaP + H2O
In this reaction, the moles of KHP will react with an equal number of moles of NaOH. The stoichiometric relationship allows us to determine the moles of NaOH used during the titration, which is used to calculate its molarity.
However, if the KHP contains moisture, the additional water molecules will contribute to the mass of the KHP sample but will not participate in the reaction with NaOH. As a result, the student will measure a higher mass of KHP, leading to the overestimation of the moles of KHP. Consequently, the calculated molarity of the NaOH solution would be too high.
To avoid this error, students should always ensure that the KHP is properly dried before use. This can be done by heating the KHP in an oven or desiccator to remove any moisture content before measuring its mass for the experiment.