1) The answer is: the number of moles is 0.5 mol and the number of grams of solute is 29.22 grams.
V(NaCl) = 1.0 L; volume of the solution.
c(NaCl) = 0.50 M; molarity of the solution.
n(NaCl) = V(NaCl) · c(NaCl).
n(NaCl) = 1 L · 0.5 mol/L.
n(NaCl) = 0.50 mol; amount of natrium chloride.
m(NaCl) = 0.50 mol · 58.44 g/mol.
m(NaCl) = 29.22 g; mass of sodium chloride.
2) The answer is: the number of grams is 22.5 g.
V(NaCl) = 2.5 L · 1000 mL/L.
V(NaCl) = 2500 mL; volume of solution.
m/v(NaCl) = 0.90%; 0.90 g of NaCl for every 100 mL of solution.
m(NaC) = 0.9 g · 2500 ml ÷ 100 mL.
m(NaC) = 22.5 g; mass of sodium chloride.
The mass/volume percent is used to express the concentration of a solution when the mass of the solute and volume of the solution is given.
3) The answer is: the concentration in percent is 5%.
m(K₂SO₄) = 75 g; mass of potassium sulfate.
V(K₂SO₄) = 1500 mL; volume of the solution.
mass/volume percent = m(K₂SO₄) ÷ V(K₂SO₄) · 100%.
mass/volume percent = 75 g ÷ 1500 mL · 100%.
mass/volume percent = 5%.
percentage concentration is mass/volume percent, which measures the mass or of solute in grams divided by the volume of solution in mililiters.
4) The answer is: volume of the concentrated acid is 0.0234 L (22.4 mL).
c₁ = 16.0 M; original concentration of the solution, before it gets diluted.
c₂ = 0.250 M; final concentration of the solution, after dilution.
V₁ = ?; volume to be diluted.
V₂ = 1.5 L; final volume after dilution.
c₁ · V₁ = c₂ · V₂.
V₁ = c₂ · V₂ ÷ c₁.
V₁ = 0.25 M · 1.5 L ÷ 16 M.
V₁ = 0.0234 L = 23.4 mL.