What mass of hydrogen gas will be formed when 125 ml of 0.500 M hydrochloric acid is reacted according to the following equation:
Mg(s)+2HCl(aq) =H2(g)+MgCl2(aq)
To solve this problem, we need to use stoichiometry to determine the amount of hydrogen gas formed.
1. First, let's calculate the number of moles of hydrochloric acid (HCl) used:
moles HCl = volume HCl (L) x concentration HCl (mol/L)
moles HCl = 0.125 L x 0.500 mol/L = 0.0625 mol HCl
2. According to the balanced equation, 1 mole of magnesium (Mg) reacts with 2 moles of hydrochloric acid to produce 1 mole of hydrogen gas (H2). Therefore, the moles of HCl used will also be equal to the moles of H2 formed.
3. Finally, we can convert the moles of hydrogen gas formed to grams using the molar mass of hydrogen gas (H2):
mass H2 = moles H2 x molar mass H2
mass H2 = 0.0625 mol x 2.016 g/mol = 0.1256 g
Therefore, the mass of hydrogen gas formed when 125 mL of 0.500 M hydrochloric acid is reacted is approximately 0.1256 grams.