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How do you find the pH of this?

2) If you titrate 5mL of a 1.5M NaOH solution into 25mL of 2.0M HCl, what is the pH?

2 Answers

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  • 1 decade ago
    Favorite Answer

    5 x 1.5 M = 7.5 mmoles of NaOH

    25 x 2.0M = 50mmoles of HCl

    50-7.5 = 42.5 mmoles of HCl left in 30mL of solution = 1.41 M

    HCl

    pH = -log(H+) = -log 1.41 = -0.15 (The pH is negative)

  • Dr.A
    Lv 7
    1 decade ago

    Moles NaOH = 0.005 L x 1.5 M = 0.0075

    Moles HCl = 0.025 L x 2.0 = 0.050

    Moles HCl in excess = 0.050 - 0.0075 =0.0425

    total volume = 30 mL = 0.030 L

    Molarity of HCl = 0.0425 / 0.030 L =1.4

    pH = - log 1.4 =0.15

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