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.

Hint: There are 0.10 moles 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.)
Now assume you measure out exactly 2.0 mL of aluminum chloride into a third test tube.
How many moles of aluminum chloride are in the tube?
moles

Answer 1

First question: 0.0001 mol/mL

Second question: 0.0004 mol of aluminium chloride

Step-by-step explanation:

The concentration of the initial solution is the number of moles added divided by the volume of the solution, thus the concentration of the aluminum chloride solution is:

C = 0.10/1

C = 0.10 mol/L

In 1 L there are 1,000 mL, so the concentration can be also expressed as:

C = 0.10 mol/L * 1L/1,000 mL

C = 0.0001 mol/mL

So, if a sample of this solution is taken in a test tube, the concentration remains constant, but the number of moles will be altered:

0.0001 mol/mL = n/4mL

n = 0.0004 mol of aluminum chloride

Answer 2

Answers:
1. 0.00010 mol/m
2. 0.00020 moles