# chemistry

A 275 mL sample of 1-propylamine vapor (in equilibrium with the liquid) at 25 °C is removed
and dissolved in 0.500 L of H2O. For 1-propylamine, Kb = 3.72 x 10-4
and the vapor pressure at
25.0 °C is 316 Torr.
a. What should be the pH of the aqueous solution?
b. How many milligrams of NaOH dissolved in 0.500 L of water give the same pH?

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1. 1. Use ideal gas law to determine moles of ProAm.
Be sure to convert given data to units of R-Value.
2. Determine concentration in 0.500L soln. =[moles ProAm/Volume(L)].
3. Determine [OH]=SqrRt([ProAm]Kb)
4. Determine pOH=-log[OH]
5. Determine pH=14-pOH
(I got pH = 11.5).
PART II:
1. [NaOH] => pH=11.5 => Same[OH]in Part I.
2. Determine moles NaOH in 0.500L = 1/2[OH] fm part I.
3. Multiply by 40 gms/mole then multiply by 1000 => mg. NaOH.
(I got 66mg/0.50L)

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