Mercury chloride is a commercial fungicide. if the molar mass is 470 g/mol and the percent composition is 85.0% hg and 15.0% cl, what is the empirical and molecular formula of the fungicide?

Data: molar mass 470 g/mol

Percent composition:

Hg = 85.0%
Cl = 15.0%

Solution:

1)  Convert % to molar ratios

A. Base: 100 g

=> Hg = 85.0 g / 200.59 g/mol = 0.4235 mol

     Cl = 15.0 g / 35.45 g/mol = 0.4231 mol

B. divide by the higher number and round to whole number

Hg = 0.4325 / 0.4231 = 1.00

Cl = 0.4231 / 0.4231 = 1.00

=> Empirical formula = Hg Cl

2) Find the mass of the empirical formula:

HgCl: 200.59 g/mol + 35.45 g/mol = 236.04

3) Determine how many times is the empirical mass contained in the molecular mass:

470 g/mol / 236.04 = 1.99 ≈ 2

=> Molecular formula = Hg2 Cl2.

Answers:

Empirical formula HgCl
Molecular Formula Hg2Cl2

pH = 11.30

Explanation:

pH is defined as -log [H⁺]

To find [H⁺] from [OH⁻] -Concentration of hydroxide ion-, we must use the equilibrium of water:

H₂O(l) ⇄ H⁺(aq) + OH⁻(aq)

Keq = 1x10⁻¹⁴ = [H⁺] [OH⁻]

[H⁺] = 1x10⁻¹⁴ / [OH⁻]

[H⁺] = 1x10⁻¹⁴ / 2x10⁻³M

[H⁺] = 5x10⁻¹²M

pH = -log (5x10⁻¹²M)

pH = 11.30