1. (a) What is the Na+ concentration in each of thefollowing solutions:
2.85 M sodium sulfate:
2.18 M sodium carbonate:
0.985 M sodium bicarbonate:
(b) What is the concentration of a lithium carbonate solutionthat is 0.395 M in Li+? M
2. A sample of 0.7160 g of an unknown compound containing bariumions (Ba2+) is dissolved in water and treated with anexcess of Na2SO4. If the mass of theBaSO4 precipitate formed is 0.6894 g, what is thepercent by mass of Ba in the original unknown compound?
3. A 0.9080 g sample of a mixture of NaCl and KCl is dissolvedin water, and the solution is then treated with an excess ofAgNO3 to yield 1.953 g of AgCl. Calculate the percent bymass of each compound in the mixture.
% mass NaCl
% mass KCl
4. The concentration of lead ions (Pb2+) in a sampleof polluted water that also contains nitrate ions(NO3−) is determined by adding solid sodiumsulfate (Na2SO4) to exactly 500 mL of thewater. Calculate the molar concentration of Pb2+ if0.00260 g of Na2SO4 was needed for thecomplete precipitation of lead ions as PbSO4.
5. Consider the reaction
H2(g) + Cl2(g) →2HCl(g) Δ H = −184.6 kJ/mol
If 5.0 moles of H2 reacts with 5.0 moles ofCl2 to form HCl at 1.0 atm, what is Δ U forthis reaction? Assume the reaction goes to completion and ΔV = 0 L.
(The conversion factor is 1 L atm = 101.3 J.)
