10 pts) A student titrates a 20.00 mL sample of an aqueous borax solution with 1.03 M H2SO4. If 2.07 mL of acid are needed to reach the equivalence point, then what is the molarity of the borax solution

Respuesta :

Answer: The molarity of the borax solution is 0.107 M

Explanation:

The neutralization reaction is:

[tex]Na_2B_4O_7.10H_2O+H_2SO_4(aq)\rightarrow Na_2SO_4+4H_3BO_3+5H_2O[/tex]

According to neutralization law:

[tex]n_1M_1V_1=n_2M_2V_2[/tex]

where,

[tex]n_1[/tex] = basicity of [tex]H_2SO_4[/tex] = 2

[tex]n_2[/tex] = acidity of borax = 2

[tex]M_1[/tex] = concentration of [tex]H_2SO_4[/tex] = 1.03 M

[tex]M_2[/tex] = concentration of borax =?

[tex]V_1[/tex] = volume of [tex]H_2SO_4[/tex]  = 2.07ml

[tex]V_2[/tex] = volume of borax = 20.0 ml

Now put all the given values in the above law, we get the molarity of borax:

[tex](2\times 1.03\times 2.07)=(2\times M_2\times 20.0)[/tex]

By solving the terms, we get :

[tex]M_2=0.107M[/tex]

Thus the molarity of the borax solution is 0.107 M