27.0 L of HCl gas at STP is dissolved in water, giving 785 mL of solution.  What is the molarity of the HCl solution?

    9.46 M

    1.53 M

    0.946 M

    15.3 M

    None of the above is within 1% of the correct answer.

3 Answers

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  • 3 weeks ago
    Best Answer

    (27.0 L) / (22.4 L/mol) / (0.785 L) = 1.5355 mol/L

    So choose the second option.

  • Anonymous
    3 weeks ago

    27 L of HCl is just over 1 mole (1 mole of any ideal gas at STP occupies 22.4 L)

    You can look at the choices and pick the second without pulling out the calculator.

  • 27 liters at STP.  At STP, 1 mole of gas occupies 22.4 Liters of space.

    27/22.4 = # of moles of HCl gas.  You dissolve this in 785 mL, so how many moles would you need for 1 liter?

    k / (27/22.4) = 1000 / 785

    k = (1000/785) * (27/22.4)

    k = 27000 / (22.4 * 785)

    k = ‭1.5354868061874431301182893539581‬...

    1.53 M would work

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