The concentration of Pb2+ in a sample of wastewater is to be determined by using

gravimetric analysis. To a 100.0-mL sample of the wastewater is added an excess of
sodium carbonate, forming the insoluble lead (II) carbonate (267.2092 g/mol) according to
the balanced equation given below. The solid lead (II) carbonate is dried, and its mass is
measured to be 0.4078 g. What was the concentration of Pb2+ in the original wastewater
sample?

The M of Na2CO3 is .0054M. I don’t know what’s next. I think that that’s the answer.

To determine the concentration of Pb2+ in the original wastewater sample, we'll follow these steps:

Step 1: Calculate the moles of PbCO3 formed.
Step 2: Calculate the moles of Pb2+ in the original wastewater sample.
Step 3: Calculate the concentration of Pb2+ in the wastewater sample.

Step 1: Calculate the moles of PbCO3 formed.
The molar mass of PbCO3 is 267.2092 g/mol.
The mass of PbCO3 formed is 0.4078 g.

Moles of PbCO3 = mass / molar mass
Moles of PbCO3 = 0.4078 g / 267.2092 g/mol

Step 2: Calculate the moles of Pb2+ in the original wastewater sample.
According to the balanced equation, the stoichiometric ratio between PbCO3 and Pb2+ is 1:1.

Moles of Pb2+ = Moles of PbCO3

Step 3: Calculate the concentration of Pb2+ in the wastewater sample.
The volume of the sample used is 100.0 mL, which is equivalent to 0.1000 L.

Concentration of Pb2+ = Moles of Pb2+ / Volume of sample (in L)
Concentration of Pb2+ = Moles of Pb2+ / 0.1000 L

By following these steps, you can calculate the concentration of Pb2+ in the original wastewater sample.

To determine the concentration of Pb2+ in the original wastewater sample, we need to follow these steps:

1. Write the balanced chemical equation:

Pb2+ (aq) + CO32- (aq) -> PbCO3 (s)

2. Determine the moles of PbCO3 formed:

First, calculate the molar mass of PbCO3:
Molar mass of PbCO3 = 207.2 g/mol + 12.0 g/mol + 48.0 g/mol = 267.2092 g/mol

Next, use the given mass of PbCO3 (0.4078 g) to find the number of moles:
Moles of PbCO3 = mass of PbCO3 / molar mass of PbCO3

3. Convert moles of PbCO3 to moles of Pb2+:

From the balanced chemical equation, we see that the mole ratio between Pb2+ and PbCO3 is 1:1. Therefore, the moles of Pb2+ will be equal to the moles of PbCO3.

4. Calculate the volume of the original wastewater sample:

Since we are given the volume of the sample (100.0 mL), we don't need to convert to volume.

5. Calculate the concentration of Pb2+:

Concentration = Moles of Pb2+ / Volume of sample

Now let's go through the calculations:

Molar mass of PbCO3 = 267.2092 g/mol
Mass of PbCO3 = 0.4078 g
Moles of PbCO3 = 0.4078 g / 267.2092 g/mol
Moles of Pb2+ = Moles of PbCO3 = 0.4078 g / 267.2092 g/mol
Volume of sample = 100.0 mL

Concentration of Pb2+ = Moles of Pb2+ / Volume of sample

Plug in the values:

Concentration of Pb2+ = (0.4078 g / 267.2092 g/mol) / 100.0 mL

Now you can solve the equation to find the concentration of Pb2+ in the original wastewater sample.

0.001526 M