The Concentration of Cu2+ ions in the water (which also contains sulfate ions) discharged from a certain industrial plant is determined by adding excess sodium sulfide(Na2S) solution to .800 L of the water. Molecular Equation:
Na2S(aq) CuSO4(aq) --> Na2SO4(aq) + CuS(s)
Write the net ionic equation and calculate the molar concentration of Cu2+ in the water sample if .0177g of solid CuS is formed.
S^2- + Cu^2+ = CuS(s)
.0177g CuS / molar mass CuS= Moles of CuS
Moles of CuS= Moles of Cu
Moles Cu/ Initial volume= Molarity of Cu
Looks Ok to me. remember to include the leading zero with values, so 0.800 L because this looked like 800 L.
The net ionic equation for the reaction can be obtained by removing the spectator ions, which are the ions that do not participate in the formation of the solid product. In this case, the sodium and sulfate ions are the spectator ions.
The balanced molecular equation is:
Na2S(aq) + CuSO4(aq) → Na2SO4(aq) + CuS(s)
To obtain the net ionic equation, we only consider the species that undergo a change in their states:
Cu2+(aq) + S2-(aq) → CuS(s)
From the net ionic equation, we can see that the molar ratio between Cu2+ and CuS is 1:1. Thus, the molar amount of Cu2+ would be equal to the molar amount of CuS.
To calculate the molar concentration of Cu2+, we need to determine the molar amount of CuS formed. We can use the molar mass of CuS to convert the given mass of CuS into moles.
The molar mass of CuS is:
Cu: 63.55 g/mol
S: 32.07 g/mol
CuS: (63.55 g/mol) + (32.07 g/mol) = 95.62 g/mol
Now, we can calculate the moles of CuS using the given mass:
Moles of CuS = Mass of CuS / Molar mass of CuS
Moles of CuS = 0.0177 g / 95.62 g/mol
Moles of CuS ≈ 0.000185 mol
Since the molar ratio between Cu2+ and CuS is 1:1, the molar concentration of Cu2+ is also approximately 0.000185 mol/L.
Therefore, the molar concentration of Cu2+ in the water sample is approximately 0.000185 mol/L.
To write the net ionic equation, you will need to identify the ions that are present in the solution before and after the reaction. In this case, the reactants are Na2S(aq) and CuSO4(aq), and the products are Na2SO4(aq) and CuS(s).
First, let's write the molecular equation:
Na2S(aq) + CuSO4(aq) -> Na2SO4(aq) + CuS(s)
The next step is to write the balanced complete ionic equation by separating all of the soluble ionic compounds into their individual ions:
2Na+(aq) + S2-(aq) + Cu2+(aq) + SO4^2-(aq) -> 2Na+(aq) + SO4^2-(aq) + CuS(s)
Now, we can cancel out the spectator ions (ions that appear on both sides of the equation, and do not participate in the reaction), which are Na+ and SO4^2-:
S2-(aq) + Cu2+(aq) -> CuS(s)
This is the net ionic equation for the reaction.
To calculate the molar concentration of Cu2+ in the water sample, we need to use the stoichiometry of the reaction, along with the given mass of CuS. Here are the steps to follow:
1. Convert the mass of CuS to moles:
- The molar mass of CuS is:
Cu: 63.55 g/mol
S: 32.07 g/mol
- Calculate the moles of CuS:
Moles of CuS = (0.0177 g) / (63.55 g/mol + 32.07 g/mol)
2. Determine the stoichiometric ratio:
- From the balanced net ionic equation, we know that 1 mole of CuS is formed for every 1 mole of Cu2+.
- Therefore, the moles of Cu2+ = Moles of CuS.
3. Calculate the volume of the water sample:
- Given that the volume of the water sample is 0.800 L.
4. Determine the molar concentration of Cu2+:
- Molar concentration (M) = Moles of Cu2+ / Volume of solution (L)
By following these steps, you should be able to calculate the molar concentration of Cu2+ in the water sample.