Question

How many milliliters of calcium, with a density of 1.55 g/mL, are needed to produce 76.4 grams of calcium fluoride in the single replacement reaction below? Be sure to show the work that you did to solve this problem.

Unbalanced equation: Ca + HF ---> CaF2 + H2

Answer 1

First need to write balanced equation: Ca + 2 HF ---> CaF2 + H2
Convert 76.4 g CaF2 into moles: MW = 1(40.078) + 2(18.998) = 78.074 g/mole Moles: (76.4 g)(1 mole / 78.074 g) = 0.9786 moles
By stoichiometry: 1 mole Ca is needed for every mole of CaF2 produced So we need 0.9786 moles Convert this to mass: (0.9786 moles)(40.078 g/mole) = 39.22 g Ca needed
(39.22 g)(1 mL / 1.55 g) = 25.3 mL
We need 25.3 mL of Ca solution


I hope this helps!