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A 15.00-ml sample of a naoh solution of unknown concentration requires 17.88 ml of a 0.1053 m h2so4 solution to reach the equivalence point in a titration. What is the concentration of the naoh solution?

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Answer:

  • 0.1255 M

Explanation:

1) Data:

Base: NaOH

Vb = 15.00 ml = 15.00 / 1,000 liter

Mb = ?

Acid: H₂SO₄

Va = 17.88 ml = 17.88 / 1,000 liter

Ma = 0.1053

2) Chemical reaction:

The titration is an acid-base (neutralization) reaction to yield a salt and water:

  • Acid + Base → Salt + Water

  • H₂SO₄ (aq) + NaOH(aq) → Na₂SO₄ (aq) + H₂O (l)

3) Balanced chemical equation:

  • H₂SO₄ (aq) + 2 NaOH(aq) → Na₂SO₄ (aq) + 2H₂O (l)

Placing coefficient 2 in front of NaOH and H₂O balances the equation

4) Stoichiometric mole ratio:

The coefficients of the balanced chemical equation show that 1 mole of H₂SO₄ react with 2 moles of NaOH. Hence, the mole ratio is:

  • 1 mole H₂SO₄ : 2 mole NaOH

5) Calculations:

a) Molarity formula: M = n / V (in liter)

   ⇒ n = M × V

b) Nunber of moles of acid:

  • nₐ = Ma × Va = 0.1053 (17.88 / 1,000)

c) Number of moles of base, nb:

  • nb = Mb × Vb = Mb × (15.00 / 1,000)

d) At equivalence point number of moles of acid = number of moles of base

  • nₐ = nb

  • 0.1053 × (17.88 / 1,000) =  Mb × (15.00 / 1,000)

  • Mb = 0.1053 × 17.88  / 15.00 = 0.1255 mole/liter = 0.1255 M

Answer: The concentration of NaOH solution is 0.25 M

Explanation:

Molarity of a solution is defined as the number of moles of solute dissolved per Liter of the solution.

According to the neutralization law,

[tex]n_1M_1V_1=n_2M_2V_2[/tex]

where,

[tex]M_1[/tex] = molarity of [tex]H_2SO_4[/tex] solution = 0.1053 M

[tex]V_1[/tex] = volume of [tex]H_2SO_4[/tex] solution = 17.88 ml

[tex]M_2[/tex] = molarity of [tex]NaOH[/tex] solution = 0.46 M

[tex]V_2[/tex] = volume of [tex]NaOH[/tex] solution = 15.0 ml

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

[tex]n_2[/tex] = valency of [tex]NaOH[/tex] = 1

[tex]2\times 0.1053M\times 17.88=1\times M_2\times 15[/tex]

[tex]M_2=0.25[/tex]

Therefore, the concentration of  NaOH solution is 0.25 M

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