A solution contains an unknown amount of dissolved magnesium. Addition of 3.38×10−2mol of Na2CO3 causes complete precipitation of all of the magnesium.
What mass of magnesium was dissolved in this solution?
Mg ^2+(aq) + Na2CO3(aq) ==> MgCO3(s) + 2Na^2+
mols Na2CO3 = 0.0338
mols Mg = mols Na2CO3 (look at the coefficients in the balanced equation.
g Mg = mols Mg x atomic mass Mg = ?
To find the mass of magnesium that was dissolved in the solution, we need to determine the number of moles of magnesium initially present.
The balanced chemical equation for the reaction between magnesium ions (Mg^2+) and carbonate ions (CO3^2-) is:
Mg^2+ + CO3^2- → MgCO3
From the equation, we can see that 1 mole of magnesium reacts with 1 mole of carbonate to form 1 mole of magnesium carbonate.
Given that 3.38×10^−2 moles of Na2CO3 (carbonate) were added and that all the magnesium precipitated, we can assume that an equal number of moles of magnesium reacted.
Therefore, the mass of magnesium that was dissolved in the solution is equal to the molar mass of magnesium multiplied by the number of moles:
Mass of magnesium = (molar mass of magnesium) × (number of moles of magnesium)
The molar mass of magnesium (Mg) is approximately 24.31 g/mol.
Substituting the values into the formula:
Mass of magnesium = (24.31 g/mol) × (3.38×10^−2 mol)
Calculating:
Mass of magnesium = 0.829 g
Therefore, the mass of magnesium that was dissolved in this solution is approximately 0.829 grams.
To determine the mass of magnesium that was dissolved in the solution, we need to use stoichiometry and the balanced chemical equation for the reaction between magnesium and sodium carbonate.
The balanced chemical equation for the reaction is:
Mg + Na2CO3 -> MgCO3 + 2Na
From the equation, we can see that 1 mole of magnesium reacts with 1 mole of sodium carbonate to produce 1 mole of magnesium carbonate.
Given that 3.38×10^-2 mol of sodium carbonate causes complete precipitation of the magnesium, we know that the same amount of moles of magnesium was dissolved in the solution.
Now, we need to convert the moles of magnesium to grams using its molar mass.
The molar mass of magnesium (Mg) is approximately 24.31 g/mol.
To calculate the mass of magnesium:
Mass = Moles × Molar Mass
Mass of magnesium = 3.38×10^-2 mol × 24.31 g/mol
Mass of magnesium = 0.822 g
Therefore, approximately 0.822 grams of magnesium was dissolved in the solution.