Determine which elements are balanced and unbalanced for each chemical equation below when every compound is given a coefficient of one.

H2 + O2 ---> H2O The hydrogen are balanced, but the oxygens are not. We have to get both balanced. We put a two in front of the water and this balances the oxygen. H2 + O2 ---> 2H2O However, this causes the hydrogen to become unbalanced. To fix this, we place a two in front of the hydrogen on the left side. 2H2 + O2 ---> 2H2O This balances the equation.

The fluoride which precipitates first is CaF₂

Explanation:

When F⁻ is added, CaF₂ and BaF₂ are produced following the ksp equation:

For CaF₂:

Ksp = 3.2x10⁻¹¹ = [Ca²⁺] [F⁻]²

Where [Ca²⁺] = 0.075M * {35mL / (25mL + 35mL)} = 0.04375M

3.2x10⁻¹¹ = [0.04375M] [F⁻]²

[F⁻]² = 7.31x10⁻¹⁰

[F⁻] = 2.7x10⁻⁵M

CaF₂ begins precipitation when [F⁻] = 2.7x10⁻⁵M.

For BaF₂:

Ksp = 1.5x10⁻⁶ = [Ba²⁺] [F⁻]²

Where [Ba²⁺] = 0.090M * {25mL / (25mL + 35mL)} = 0.0375M

1.5x10⁻⁶ = [0.0375M] [F⁻]²

[F⁻]² = 4x10⁻⁵

[F⁻] = 6.3x10⁻³M

BaF₂ begins precipitation when [F⁻] = 6.3x10⁻³M

Thus, the fluoride which precipitates first is CaF₂