Part 1 - KHP Titrations

Question

Question 2 (1 point)
A student performed three KHP titrations in Part 1 in order to standardize their NaOH solution. They reported the following measurements:

Determination #1 Determination #2 Determination #3
Mass of KHP + Vial 15.4229 g 15.4250 g 15.4248 g
Mass of 'Empty' Vial 14.8284 g 14.7505 g 14.8002 g
Final Burette Reading 28.51 mL 32.51 mL 30.97 mL
Initial Burette Reading 0.25 mL 0.51 mL 1.23 mL
How many moles of KHC8H4O4 did they use in their third titration (ie. their third determination)? Report your answer to the correct number of significant figures and only report the numerical value (no units).

Answer 1

To find the number of moles of KHC8H4O4 (KHP) used in the third titration, we first need to calculate the mass of KHP used in this determination, and then convert that mass into moles.

1. Calculate the mass of KHP used in the third determination:

\[ \text{Mass of KHP} = \text{Mass of KHP + Vial} - \text{Mass of 'Empty' Vial} \]

For determination #3:

\[ \text{Mass of KHP} = 15.4248 , \text{g} - 14.8002 , \text{g} = 0.6246 , \text{g} \]

2. Now convert the mass of KHP to moles. The molar mass of KHC8H4O4 is approximately 204.22 g/mol.

\[ \text{Number of moles of KHP} = \frac{\text{mass of KHP}}{\text{molar mass of KHP}} = \frac{0.6246 , \text{g}}{204.22 , \text{g/mol}} \]

Calculating this gives:

\[ \text{Number of moles of KHP} \approx 0.003058 , \text{mol} \]

3. Reporting the final answer to the correct number of significant figures (based on the mass measured, which has four significant figures):

\[ \text{Number of moles of KHP} \approx 0.003058 \]

The final answer to report is:

0.003058