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Ethylene diamine tetra-acetic acid (EDTA) is a water-soluble compound that readily combines with metals, such as calcium, magnesium, and iron. The molecular formula for EDTA is C10N2O8H16. One EDTA molecule complexes (associates with) one metal atom. A factory produces an aqueous waste that contains 20 mg/L calcium and collects the waste in 44-gallon drums. What mass (g) of EDTA would need to be added to each drum to completely complex all of the calcium in the barrel? (1 gal = 3.785 L)

Respuesta :

Answer: The mass of EDTA that would be needed is 24.3 grams.

Explanation:

We are given:

Concentration of [tex]Ca^{2+}[/tex] ions = 20 mg/L

Converting this into grams/ Liter, we use the conversion factor:

1 g = 1000 mg

So, [tex]\Rightarrow \frac{20mg}{L}\times {1g}{1000mg}=0.02g/L[/tex]

Now, we need to calculate the mass of calcium present in 44 gallons of drum.

Conversion factor used:  1 gallon = 3.785 L

So, 44 gallons = (44 × 3.785)L = 166.54 L

Calculating the mass of calcium ions in given amount of volume, we get:

In 1L of volume, the mass of calcium ions present are 0.02 g.

Thus, in 166.54 L of volume, the mass of calcium ions present will be = [tex]\frac{0.02g}{1L}\times 166.54L=3.3308g[/tex]

The chemical equation for the reaction of calcium ion with EDTA to form Ca[EDTA] complex follows:

[tex]EDTA+Ca^{2+}\rightarrow Ca[EDTA][/tex]

Molar mass of EDTA = 292.24 g/mol

Molar mass of [tex]Ca^{2+}[/tex] ion = 40 g/mol

By Stoichiometry of the reaction:

40 grams of calcium ions reacts with 292.24 grams of EDTA.

So, 3.3308 grams of calcium ions will react with = [tex]\frac{292.24g}{40g}\times 3.3308g=24.33g[/tex] of EDTA.

Hence, the mass of EDTA that would be needed is 24.3 grams.

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