pH (1 Viewer)

[tennille]

Hey, I'm really having trouble with a question I received in a practice paper. Could anyone help?

18g of H2SO4 is completely dissolved in 250mL of distilled water. 3g of Mg is then added to this solution. Calculate the pH of the solution after the Mg has completely reacted with the acid.

I'd really appreciate your help.

Thanks.

 

[Xayma]

Mg_(s)+H₂SO_4(aq)------>MgSO4_(aq)+H_2(g)

n_Mg=m_Mg/M_Mg
=3/24.3
=0.1234567mol (yes I rounded to 1 dp above purely to get that and ignored rounding that off but it doesn't affect the final answer)

Therefore 0.1234567mol of H₂SO₄ was removed.

n_H₂SO₄(i)=18/98.072
=.1835
∴
n_H₂SO₄(f)=.0601
n_H⁺=2n_H₂SO₄(f)
=.1202
c=n/v
=.1202/.25
=.4808
pH=-log₁₀ .4808
=0.32

 

[tennille]

thanks for that.

 

[Paroissien]

Wow that's is one acidic solution