How many grams of Magnesium would need to be used to donate as many electrons as 50g of Sodium (

Question

CRB Equivalents are related to limiting reagents, because using a different compound means a different mass needs to be used to have the same effect (whether in buffering, electrons to donate or protons to donate). How many grams of Magnesium would need to be used to donate as many electrons as 50g of Sodium (periodic table: http://www.chem.qmul.ac.uk/iupac/AtWt/table.gif)?

(A) 57.6 g

(B) 82.1 g

(C) 15.2 g

(D) 26.4 g

Answer 1

Atomic mass of sodium (Na) = 22.99 g / mol

50 g Na x 1 mol Na / 22.99 g = 2.17 moles Na

Na ==> Na⁺ + 1e- .. ionization of Na

2.17 moles Na = 2.17 moles of electrons

Atomic mass of magnesium (Mg) = 24.31

Mg ==> Mg²⁺ + 2e-

2.17 moles of electrons x 1 mole Mg / 2 moles e- = 1.085 moles Mg to get same number of electrons

1.085 mols Mg x 24.31 g / mol = 26 g Mg needed ANSWER D