Answer:
Pb(NO₃)₂ = 0.05 M
PbSO₄ = 0.05 M
NaNO₃= 0.1 M
Step-by-step explanation:
The ions in lead(II) nitrate are Pb⁺² and NO₃⁻, so its formula is Pb(NO₃)₂. The ions of sodium sulfate are Na⁺ and SO₄²⁻, so its formula is Na₂SO₄. The reaction will be:
Pb(NO₃)₂(aq) + Na₂SO₄(aq)→ PbSO₄(s) + 2NaNO₃(aq)
For the sulfates, the lead sulfate is insoluble. The salts formed by elements from group 1 are solubles (such as sodium). So the precipitated formed is PbSO₄, and because it is insoluble, the reaction can be considered irreversible.
The number of moles of each reactant is the concentration multiplied by the volume in L (0.90 mL = 0.0009 L):
Pb(NO₃)₂ = 0.20x0.0009 = 0.00018 mol
Na₂SO₄ = 0.1x0.0009 = 0.00009 mol
The stoichiometry is 1 mol of Pb(NO₃)₂ from 1 mol of Na₂SO₄, so Pb(NO₃)₂ is in excess (by double) and Na₂SO₄ is the limiting reactant and it's all consumed.
The stoichiometry calculus must be done with the limiting reactant. So, for Pb(NO₃)₂, the number of moles resulting will be:
Pb(NO₃)₂ = 0.00018 - 0.00009 = 0.00009 mol
For PbSO₄:
1 mol of Na₂SO₄ ---------- 1 mol of PbSO₄
PbSO₄= 0.00009 mol
For NaNO₃:
1 mol of Na₂SO₄ -------- 2 mol of NaNO₃
0.00009 mol ----------- x
By a simple direct three rule:
x = 0.00018 mol of NaNO₃
The final volume is = 0.90 + 0.9 = 1.8 mL = 0.0018 L, and the concentrations are the number of mol divided by the volume:
Pb(NO₃)₂ = 0.00009/0.0018 = 0.05 M
PbSO₄ = 0.00009/0.0018 = 0.05 M
NaNO₃= 0.00018/0.0018 = 0.1 M