Question

In the example in the lesson, 0.10 mole of sodium chloride or magnesium chloride or aluminum chloride was added to one liter of water. How many moles of each chloride are in one milliliter of the respective solutions?
Hint: There is 0.10 mole per liter. Recall how many milliliters are in a liter and divide 0.10 by that number. (Remember to use the proper number of significant figures.)

______ moles/mL

Answer 1

Answer: $0.1\times 10^{-3}$ moles/ml of chloride ion in sodium chloride solution.

$0.2\times 10^{-3}$ moles/ml of chloride ion in magnesium chloride solution.

$0.3\times 10^{-3}$ moles/ml of chloride ion in Aluminium chloride solution.

Explanation:

1) Moles of Sodium chloride in 1 liter water = 0.10 moles

$NaCl(aq)\rightarrow Na^+(aq)+Cl^-(aq)$

Moles of chloride ions = 0.10 × 1  =0.10 moles

1 liter = 1000 milliliter

Moles of chloride in 1000 mL water = 0.10 moles

Moles of chloride in 1 mL water :

=$\frac{0.10 mol}{1000}=0.1\times 10^{-3}$ moles

2) Moles of magnesium chloride in 1 liter water = 0.10 moles

$MgCl_2(aq)\rightarrow Mg^{2+}(aq)+2Cl^-(aq)$

Moles of Chloride ions = 0.10 × 2 = 0.20 moles

1 liter = 1000 milliliter

Moles of chloride in 1000 mL water = 0.20 moles

Moles of chloride in 1 mL water :

=$\frac{0.20 mol}{1000}=0.2\times 10^{-3}$ moles

3) Moles of Aluminum chloride in 1 liter water = 0.10 moles

$AlCl_3(aq)\rightarrow Al^{3+}(aq)+3Cl^-(aq)$

Moles of Chloride ions = 0.10 × 3 = 0.30 moles

1 liter = 1000 milliliter

Moles of chloride in 1000 mL water = 0.30 moles

Moles of chloride in 1 mL water :

=$\frac{0.30 mol}{1000}=0.3\times 10^{-3}$ moles

Answer 2

If There is 0.10 mole per liter and we need to recall how many milliliters are in a liter and divide 0.10 by that number then the exact quantity will be 0.00010 mol/mL