A student fills her burette with NaOH to the 2.5 mL mark. She titrated her sample of the NaOH until she reaches the endpoint (i. e. all the acid has been neutralized by the NaOH). The volume marking on her burette - at the endpoint - is 52.5 mL. How many mL of NaOH did she use to reach the endpoint

She used 50 mL of NaOH to reach the endpoint.

Explanation:

Assuming the burette is filled to the point marked 3.30 ml, You would record the initial point as 3.30 ml:

If at the end of the titration the level of the NaOH is at 20.30 mL; Subtract the initial reading from the final burette reading to get how many mL was used to reach an end point.

That is  20.3 - 3.3 = 17.00 mL

Therefore, the titration would have required 17.00 mL.

Remember that you should read the number that is at the bottom of the meniscus and at an eye level in order to avoid error.

Initial mark = 2.5 mL

Final mark = 52.5 mL.

volume used = 52.5 - 2.5

                            = 50 mL