Serenitybella
11.03.2021 •
Chemistry
Explain why the pH of an acidic solution is always a smaller number than the pOH of the same solution.
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Ответ:
27.60 g urea
Explanation:
The freezing-point depression is expressed by the formula:
ΔT= Kf * mIn this case,
ΔT = 5.6 - (-0.9) = 6.5 °CKf = 7.78 °C kg·mol⁻¹m is the molality of the urea solution in X (mol urea/kg of X)
First we calculate the molality:
6.5 °C = 7.78 °C kg·mol⁻¹ * mm = 0.84 mNow we calculate the moles of urea that were dissolved:
550 g X ⇒ 550 / 1000 = 0.550 kg X
0.84 m = mol Urea / 0.550 kg Xmol Urea = 0.46 molFinally we calculate the mass of urea, using its molecular weight:
0.46 mol * 60.06 g/mol = 27.60 g urea