$($q$)$ Practical Skill Task: Diluting a Solution

Using a $25-mL$ volumetric pipet, deliver $25\mathrm{.}00mL$ of the stock solution labeled as: $"0\mathrm{.}3000M{x}_{2}S{O}_4"$ into a

$100-$mL volumetric flask, add some de$-$ionized $($DI$)$ water, mix, and fill it to the mark with DI water and mix again

Check that the liquid level is lined up with the fill$-$line. Bring your volumetric flask to the front of the room where

your instructor will $($i$)$ check the liquid level in the flask and $($ii$)$ show you how to use a LaqQuest and

spectrophotometer to check the Absorbance of light by your dilute solution. Absorbance is proportional to

concentration, so your instructor will be able to use the Absorbance reading to judge the quality of your dilution.

$($Instructor check area $--$ Do not write inside the box below$)$

LEVEL CHECK: Awful Poor Adequate Good Excellent

SPECTROPHOTOMETER ABSORBANCE READING:

QUALITY OF DILUTION: conc. very low slightly too low conc. good slightly too high conc. very high

$($Instructor check area $--$ Do not write inside the box above$)$

$($r$)$ Clean up: Empty chemical waste in the appropriate waste container. Add about $100mL$ water to your Sparkleen $1$

powder, then wash the glassware you used, rinse with distilled water, and return them to where you got them.

Dispose of all trash. Wipe clean and dry the surface of the benchtop used to do your work on this assignment.

Dilution Calculations $-$ You may use dimensional analysis or employ the dilution equation $M_c{V}_c=M_d{V}_d,$ where the

subscript $"c"$ indicates the concentrated solution and the subscript $"d"$ indicates the dilute solution.

However you do the calculation, you must show your work. Every number must have proper units and correct

significant figures.

$($a$)$ Calculate the concentration of $x^{+}$ions in the dilute solution made in $2(q)$ above. Show all your work in the space

provided below. Every number must have proper units and correct significant figures.

$($b$)$ A dilute $CuC{l}_2$ solution is made by combining $4\mathrm{.}00mL$ of $0\mathrm{.}100MCuC{l}_2$ with $5\mathrm{.}00mL$ of distilled water. You may

assume that the final volume of the dilute solution is the sum of the two volumes combined. Calculate the

concentration of $C{u}^{2+}$ in the dilute solution.