Calculate the molarity: acids and bases

Question

Calculate the molarity of 25.0 mL of Sr(OH)2 titrated to the equivalence point with 28.9 mL of 0.250 M HBr

Answer 1

Sr(OH)₂ + 2HBr ==> SrBr₂ + 2H₂O ... balanced equation

moles HBr used = 28.9 ml x 1 L /1000 ml x 0.250 mol/L = 0.007225 moles HBr

moles Sr(OH)₂ present = 0.007225 moles HBr x 1 mole Sr(OH)₂/2 moles HBr = 0.0036125 moles Sr(OH)₂

molarity Sr(OH)₂ =0.0036125 moles/0.0250 L = 0.145 M (to 3 significant figures)