The given question is incomplete. The complete question is :
Determine the volume of 1M NaOH that is required to reach the equivalence point with 25.00 mL of HCl (of unknown concentration). From there, calculate the original concentration of the unknown HCl solution.
Volume of 1M NaOH used = 2.80 mL
Answer: Thus the original concentration of the unknown HCl solution is 0.112 M
Explanation:
The balanced chemical reaction will be :
[tex]NaOH+HCl\rightarrow NaCl+H_2O[/tex]
To calculate the concentration of acid, we use the equation given by neutralization reaction:
[tex]n_1M_1V_1=n_2M_2V_2[/tex]
where,
[tex]n_1,M_1\text{ and }V_1[/tex] are the n-factor, molarity and volume of acid which is [tex]HCl[/tex]
[tex]n_2,M_2\text{ and }V_2[/tex] are the n-factor, molarity and volume of base which is NaOH.
We are given:
[tex]n_1=1\\M_1=?\\V_1=25.00mL\\n_2=1\\M_2=1M\\V_2=2.80mL[/tex]
Putting values in above equation, we get:
[tex]1\times M_1\times 25.00=1\times 1\times 2.80\\\\M_1=0.112[/tex]
Thus the original concentration of the unknown HCl solution is 0.112 M
