Question

0.33 g of hydrosulfuric acid, H25, is added to 50.0 mL of water. What is the concentration (molarity) of [H301 of this solution?
H25 --> 2H +52
2H+ + 2 H20 --> 2 H30* + 2 OH
[Do not include units in your answer]

Answer 1

The concentration (molarity) of [H₃O⁺]=0.776 M

Further explanation

We balance the reaction first so that the number of atoms and the charge of the product and reactant are the same

Reaction(balanced) :

H₂S⇒2H⁺+S²⁻ (eq 1)

2H⁺+6H₂O⇒4H₃O⁺+2OH⁻ (eq 2)

mass of H₂S=0.33 g

mol H₂S (MW=34 g/mol) :

$\tt mol=\dfrac{0.33}{34}=0.0097$

From equation 1, mol H⁺ = 2 x mol H₂S , so mol H⁺ =

$\tt 2\times 0.0097=0.0194$

From equation 2, mol H₃O⁺ = 2 x mol H⁺(4 : 2) , so mol H₃O⁺ :

$\tt 2\times 0.0194=0.0388$

Or simply mol H₃O⁺ = 4 x mol H₂S = 4 x 0.0097 = 0.0388

the molarity of [H₃O⁺] =

$\tt M=\dfrac{n}{V}=\dfrac{0.0388}{0.05~L(50~ml)}=0.776$