Answer:
87.5 g/mol, Sr (strontium)
Explanation:
The reaction between the metal and the acid is:
X + H₂SO₄ → 2H⁺ + XSO₄ (ion sulfate is SO₄⁻²)
The initial number of moles of the acid is the concentration multiplied by the volume:
n = 0.500*0.1 = 0.05 mol
The reaction between the acid and the base is:
H₂SO₄ + NaOH → NaHSO₄ + H₂O
The number of moles of NaOH is:
0.0543x0.5 = 0.02715 mol
Which is the same number of moles of H₂SO₄, because of the stoichiometry 1:1. So, in the first reaction, reacted:
0.05 - 0.02715 = 0.02285 mol of H₂SO₄
And, for the stoichiometry, there was 0.02285 mol of X. The molar mass of X is the mass divided by the number of moles:
2/0.02285 = 87.5 g/mol
For the periodic table, X is Sr, strontium.
