A 0.250- sample of a magnesium-aluminum alloy dissolves completely in an excess

Question

A 0.250- sample of a magnesium-aluminum alloy dissolves completely in an excess of . When the liberated is collected over water at 29 and 752 , the volume is found to be 305 . The vapor pressure of water at 29 is 30.0 How many moles of can be produced from grams of in magnesium-aluminum alloy? The molar mass of is 24.31 . Express your answer in terms of to four decimal places (i.e., 0.5000x).

Explanation / Answer

At first we have to calculate the gas volume at standard condition (25°C and 760 torr) The conversation factors are 298.15 °C/(298.15 °C + 4°C) and 760 torr/(752 torr - 30 torr). The result is V = 323.4 mL H2 under standard conditions. 24,4640424 l/mol is the molar volume of (ideal) gases. So 0.3503 L are equal to 0,0132 mol H2. The equations of reaction are: Mg +2 HCl --> MgCl2 + H2 2 Al + 6 HCl --> 2 AlCl3 + 3 H2 --------------------------------------… Atomic mass of Mg is 24.7 g/mol and of Al = 27 g/mol. If all of the alloy was Al, we have to calculate the mass of Al = 2/3*mol[H2]*27 g/mol =238 mg. If it all was Mg we calculate mol[H2]*24.7= 321 mg If Al is 85.5 % and Mg 14.5 % the alloy produces the amount of H2 given.

Related Questions

Navigate

• Browse (All)
• Browse A
• Subjects

---

---

Integrity-first tutoring: explanations and feedback only — we do not complete graded work. Learn more.