Question

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

Answer 1

Answer: The molarity of the borax solution is 0.107 M

Step-by-step explanation:

The neutralization reaction is:

`Na_2B_4O_7.10H_2O+H_2SO_4(aq)\rightarrow Na_2SO_4+4H_3BO_3+5H_2O`

According to neutralization law:

`n_1M_1V_1=n_2M_2V_2`

where,

`n_1` = basicity of
`H_2SO_4` = 2

`n_2` = acidity of borax = 2

`M_1` = concentration of
`H_2SO_4` = 1.03 M

`M_2` = concentration of borax =?

`V_1` = volume of
`H_2SO_4` = 2.07ml

`V_2` = volume of borax = 20.0 ml

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

`(2* 1.03* 2.07)=(2* M_2* 20.0)`

By solving the terms, we get :

`M_2=0.107M`

Thus the molarity of the borax solution is 0.107 M