Lead(II) carbonate, PbCO3, is one of the components of the passivating layer that forms inside lead pipes. (d) The EPA threshold for acceptable levels of lead ions in water is 15 ppb. Does a saturated solution of lead(II) carbonate produce a solution that exceeds the EPA limit?
Verified step by step guidance
1
Step 1: Write the dissolution equation for lead(II) carbonate: PbCO_3(s) \rightleftharpoons Pb^{2+}(aq) + CO_3^{2-}(aq).
Step 2: Use the solubility product constant (K_{sp}) for PbCO_3 to express the equilibrium concentrations of the ions. The K_{sp} expression is K_{sp} = [Pb^{2+}][CO_3^{2-}].
Step 3: Assume the solubility of PbCO_3 is 's' mol/L. At equilibrium, [Pb^{2+}] = s and [CO_3^{2-}] = s. Substitute these into the K_{sp} expression to solve for 's'.
Step 4: Convert the solubility 's' from mol/L to ppb (parts per billion) for lead ions. Use the molar mass of lead to convert moles to grams, and then convert grams to ppb.
Step 5: Compare the calculated ppb of lead ions in the saturated solution to the EPA threshold of 15 ppb to determine if the solution exceeds the limit.
Verified video answer for a similar problem:
This video solution was recommended by our tutors as helpful for the problem above.
Video duration:
6m
Play a video:
Was this helpful?
Key Concepts
Here are the essential concepts you must grasp in order to answer the question correctly.
Solubility Product Constant (Ksp)
The solubility product constant (Ksp) is a numerical value that represents the extent to which a compound can dissolve in water. For lead(II) carbonate, PbCO3, Ksp can be used to determine the concentration of lead ions in a saturated solution. If the concentration of lead ions exceeds the EPA limit of 15 ppb, the solution is considered unsafe.
Lead(II) carbonate dissociates in water to produce lead ions (Pb²⁺) and carbonate ions (CO3²⁻). The equilibrium established during this dissociation is crucial for calculating the concentration of lead ions in a saturated solution. Understanding this dissociation helps in assessing whether the lead concentration surpasses regulatory limits.
Parts per billion (ppb) is a unit of measurement used to express very dilute concentrations of substances. In the context of water quality, it indicates the number of parts of a substance per billion parts of water. The EPA's threshold of 15 ppb for lead ions is critical for determining the safety of drinking water, making it essential to compare the calculated lead concentration against this standard.
01:47
