Consider the titration of a 26.1 −mL sample of 0.125 M RbOH with 0.110 M HCl. Determine each of the following. the initial pH
the volume of added acid required to reach the equivalence point
the pH at 6.0 mL of added acid
the pH at the equivalence point
the pH after adding 4.8 mL of acid beyond the equivalence point

We're asked to find the molar concentration of the

NaCl

solution given some titration data.

Let's first write the chemical equation for this reaction:

NaOH

(

a

q

)

+

HCl

(

a

q

)

→

NaCl

(

a

q

)

+

H

2

O

(

l

)

Using the molarity equation, we can find the number of moles of

HCl

that reacted:

molarity

=

mol solute

L soln

mol solute

=

(

molarity

)

(

L soln

)

mol HCl

=

(

0.105

mol

L

)

(

0.0250

L

)

=

0.00263

mol HCl

(volume converted to liters)

Now, using the coefficients of the chemical reaction, we can determine the number of moles of

NaOH

that reacted:

0.00263

mol HCl

(

1

l

mol NaOH

1

mol HCl

)

=

0.00263

mol NaOH

Lastly, we'll use the molarity equation (using given volume of

NaOH soln

) again to determine the molarity of the sodium hydroxide solution:

molarity

=

mol solute

L soln

M

NaOH

=

0.00263

l

mol

0.315

l

L

=

0.00833

M

(volume converted to liters)