Answer:
The correct answer is 27.22 mg.
Explanation:
Based on the given information, the temperature of the water given is 22.4 degree C or 22.4 + 273 = 295.4 K
The volume of the gathered hydrogen is 37.1 ml or 0.0371 L
The pressure mentioned in the lab room is 29.18 in Hg or 29.18 × 2.54 = 74.1172 cm Hg.
18.4 cm is the difference given in the water level between the burette and the beaker, so the pressure is,
74.1172 cm - 18.4 cm = 55.7172 cm Hg or 557.172 mmHg
760 mmHg is equal to 1 atm, therefore, 557.172 mmHg will be equal to,
557.172 mm Hg / 760 mm Hg × 1 atm = 0.733 atm
The moles of hydrogen gas can be calculated by using the ideal gas equation, that is, PV = nRT
n = PV / RT
Putting the values we get,
n = 0.733 atm × 0.0371 L / 0.0821 atm L mol⁻¹ K⁻¹ × 295.4 K
n = 0.00112 mol
Let us consider the equation,
2 HCl + Mg ⇒ H₂ + MgCl₂
By seeing the reaction it is clear that for the generation of 1 mole of hydrogen gas, 1 mole of magnesium is needed.
The moles of magnesium is 0.00112 moles and the molecular mass of magnesium is 24.305 gram per mol
The mass of magnesium ribbon can be determined by using the formula, mass = mole × molecular mass
mass = 0.00112 mole × 24.305 g/mol
mass = 0.02722 grams or 27.22 mg.
