Question

1.) A student found that the sulfate ion concentration in a solution of Al₂(SO₄)₃ was 0.34 M. What was the concentration of Al₂(SO₄)₃ in the solution?

C(Al₂(SO₄)₃)=

2.) To study the effect of dissolved salt on the rusting of an iron sample, a student prepared a solution of NaCl by dissolving 4.250 g of NaCl in enough water to make 204.2 mL of solution. What is the molarity of this solution?

C(NaCl) =

3.) A student found that the sulfate ion concentration in a solution of Al₂(SO₄)₃ was 0.34 M. What was the concentration of Al₂(SO₄)₃ in the solution?
C(Al₂(SO₄)₃) =

4.) Strontium nitrate, Sr(NO₃)₂, is used in fireworks to produce brilliant red colors. Suppose we need to prepare 436.4 mL of 0.177 M Sr(NO₃)₂ solution. How many grams of strontium nitrate are required?
m(Sr(NO₃)₂) =

Answer 1

1) The concentration of AL2(SO4)3 must be, because of the stoichiometry of the reaction, 1/3 of the concentration of the sulfate ion:

[AL2(SO4)3]= 0.113 M
2) The molarity is de quotient of the moles of solute divided by the liters of solution. Assuming that the molar mass of NaCl is 58.44 g/mol:

3) The concentration of AL2(SO4)3 must be, because of the stoichiometry of the reaction, 1/3 of the concentration of the sulfate ion:

[AL2(SO4)3]= 0.113 M

4)Assuming the molar mass of strontium nitrate is 211,63 g/mol: