If 25 mL of a 0.5 M NaOH solution were needed to reach the equivalence point of a 20 mL HCl solution, what was the initial analyte concentration?

A. 0.0625 M
B. 0.4 M
C. 0.625 M
D. 0.5 M

Question

If 25 mL of a 0.5 M NaOH solution were needed to reach the equivalence point of a 20 mL HCl solution, what was the initial analyte concentration?

 		A.	0.0625 M
 		B.	0.4 M
 		C.	0.625 M
 		D.	0.5 M

photon336 · Answer

The equivalence point, or stoichiometric point, of a chemical reaction is the point at which chemically equivalent quantities of acid and base have been mixed.

M1V1 = M2V2

photon336 · Answer

You solve for M2 

I based this off the assumption that an equal number of moles have reacted at that point. 

M1V1/V2 = M2  = 25mL*0.5M/(20mL) = M2 0.0625

vera_ewing · Answer

It was C.

photon336 · Answer

Did mental math there sorry but based on what I did it should be 0.625 mol