In an experiment,0.243 g of magnesium reacts to give 0.403 g magnesium oxide.Using the conservation of mass law,predict the mass of reacting oxygen gas. 2 Mg(s)+ O₂(g) 2 MgO(s)

Question

In an experiment,0.243 g of magnesium reacts to give 0.403 g magnesium oxide.Using the conservation of mass law,predict the mass of reacting oxygen gas. 2 Mg(s)+ O₂(g)  2 MgO(s)

Quizplus · Accepted Answer

We can use stoichiometry to calculate the mass of oxygen gas. From the balanced chemical equation, we know that for every 2 moles of Mg, we need 1 mole of O₂ to react and form 2 moles of MgO.

First, we need to find the number of moles of Mg that reacted. We can use the formula:

moles = mass / molar mass

The molar mass of Mg is 24.31 g/mol, so:

moles of Mg = 0.243 g / 24.31 g/mol = 0.01 mol

According to the balanced chemical equation, 2 moles of Mg react with 1 mole of O₂. Therefore, to find the number of moles of O₂, we can use the ratio:

moles of O₂ = (moles of Mg) / 2 = 0.01 mol / 2 = 0.005 mol

Finally, we can find the mass of O₂ using the same formula as before:

mass = moles x molar mass

The molar mass of O₂ is 32.00 g/mol, so:

mass of O₂ = 0.005 mol x 32.00 g/mol = 0.16 g

Therefore, the correct answer is choice B: 0.160 g.

In an Experiment,0