Name _______________
Date_________________
Period__
Solution Preparation Practice Lab - SOP
Introduction:
The preparation and measuring of solutions is an important part of many lab activities. In this lab
we will practice making several solutions and learn some tricks for solution preparation that
should make every solution you will make this year much easier to do! This short exercise is
designed to acquaint you with the some of the simple calculations and lab procedures involved in
preparing solutions. The remainder of the solution preparation skills you will need will be taught
in the following labs.
Objectives:
Practice using the Solution Preparation SOP
Observe that some volumes are not additive
Produce various 100ml solutions with specific numbers of moles
Practice weighing out aliquots with accuracy
Materials:
Thermometer
150ml beaker
100ml volumetric flask
100ml graduated cylinder
10ml graduated cylinder
Deionized water squeeze bottle
Scupula
1.0ml-2.0ml Eye dropper
Small funnel
Digital scale
NaCl Stock Bottle
Sucrose Stock Bottle
PART I
Beakers vs. graduated Cylinders vs. Volumetric Flasks
1. Obtain a 150ml beaker, 100ml volumetric flask, and a 100ml graduated cylinder.
2. Fill the beaker with 25˚C deionized water to the 100ml mark. It may be helpful to use a
dropper to add the last bit of water drop-wise.
3. Using a funnel pour all of the water in the beaker into the 100ml volumetric.
4. Record where the meniscus line is on volumetric flask A on next page.
5. Now pour it into the 100ml graduated cylinder and record the volume it reads at (be sure
measurements are taken at meniscus). If it is over use a 10ml graduated cylinder to
measure excess. ___________
6. Dispose of water in sink.
7. Fill the 100ml graduated cylinder with 25˚C deionized water to the 100ml mark. It may
be helpful to use a dropper to add the last bit of water drop-wise (be sure measurements
are taken at meniscus).
8. Using a funnel pour all of the water in the graduated cylinder into the 100ml volumetric.
9. Record where the meniscus line is on volumetric flask B on next page.
Name _______________
Date_________________
Period__
Topping off with solvent:
A student reads directions for a lab which say a solution of isopropyl alcohol and water was
needed for a lab. The solution was to be 100ml and contain 40% isopropyl alcohol (40ml of
Isopropyl alcohol). The student figured that if since the solution was 100ml and 40ml of it was
isopropyl alcohol then 100ml-40ml = 60ml of water. They then told you to make the solution.
1. Using a 100ml graduated cylinder measure out exactly 40ml of the stock isopropyl
alcohol (be sure measurements are taken at meniscus).
2. Now pour it into the 100ml volumetric flask using a funnel
3. Fill the 100ml graduated cylinder with exactly 60ml of deionized water (be sure
measurements are taken at meniscus).
4. Now pour the water into the 100ml volumetric flask with the 40ml of isopropyl alcohol
using a funnel.
5. Record where the meniscus of the solution is on volumetric flask C.
6. Now pour the solution from the 100ml volumetric flask into a 100ml graduated cylinder
and record the volume it reads at (be sure measurements are taken at meniscus). If it is
over use a 10ml graduated cylinder to measure excess. ___________
PART II
Solution preparation:
Now that you have practiced the proper way to add a solvent to a solute and know what
glassware in most accurate let’s make some solutions! Remember that M stands for Molar (with
we will cover in the next unit) and means 1 mole of the solute per 1 liter of solution. We will be
making 100ml solutions or 0.1L.
1. Look up the molar mass of one mole of NaCl on the chemical container at the stock
bench. It may be written as the formula weight (FW) ______________
2. What are the units of this value? _____________ Remember to always include units
when reporting a value. This will help you remember what that number represents.
3. Calculate the mass of NaCl needed for a 100ml solution with 0.02moles of NaCl. Use
your Biological and Chemical Solutions Handout to help with the conversion.
_______________g NaCl
Name _______________
Date_________________
Period__
4. In this case, you are to make a 0.2 M solution of NaCl. Now weight out your calculated
mass of NaCl into a DRY 100ml volumetric flask. Insure that you zero out the scale with
the volumetric flask on it before you begin. A funnel may be help full.
5. Begin to add deionized water to the 100ml volumetric flask with the NaCl in it. Use a
squeeze bottle and fill so the bulb of the volumetric flask is almost half full.
6. Swirl the solution in the volumetric flask until the NaCl is dissolved. Often a cap on the
volumetric flask is useful. Insure no drops remain on the neck/stem of the volumetric
flask.
7. Once dissolved top off with deionized water to 100ml graduated line on volumetric flask.
The neck of the flask should be filled drop-wise with an eyedropper.
8. Dispose of it down the sink.
9. Re make the solution you just made but this time follow the 2nd Method for making
solutions.
10. After you have determined the mass of NaCl to use weigh it into the 150ml beaker,
zeroed on the scale.
11. Dissolve the NaCl with about 50ml of deionized water in the beaker.
12. Transfer the NaCl solution in the beaker into the volumetric flask.
13. Make sure to rinse the beaker with a small amount of deionized water, about 30ml and
pour into volumetric flask.
14. Now top off with deionized water to 100ml graduated line on volumetric flask. The neck
of the flask should be filled drop-wise with an eyedropper.
15. Dispose of it down the sink.
On your own:
Use your Solution Preparation SOP to assist you.
1. You need to prepare a 100ml solution of sucrose with 0.0016moles of sucrose in it.
2. Follow your SOP and prepare the solution.
3. Dispose of it down the sink.
Analysis:
Part I
Beakers vs. graduated Cylinders vs. Volumetric Flasks:
1. Did the water from the breaker’s meniscus match up exactly with the graduated 100ml
line on the volumetric flask?
2. By how many ml was the beaker off from the volumetric flack?
3. Did the water from the 100ml graduated cylinder’s meniscus match up exactly with the
graduated 100ml line on the volumetric flask?
4. By how many ml was the graduated cylinder off from the volumetric flack?
Which piece of glassware is the most accurate?
Name _______________
Date_________________
Period__
5. How could using one of the other pieces of glassware to make a solution cause a
problem?
Topping off with solvent:
6. Was the final solution you made exactly 100ml?
7. How could you have insured it was a 100ml solution with 40ml of isopropyl alcohol –
what could you have done with the water and 100ml volumetric flask? (hint look at your
Solution Preparation SOP)
8. What would be the correct way to add solvent to a solute: measure solvent out or add it
until desired solution volume? Why?
Part II
1. What were the solvent and solute in the NaCl solution?
2. Why was it necessary to wash out the 150ml beaker in step 13 of Part II Solution
Preparations?
3. What if any issues did you come across when preparing the NaCl solution?
4. How could having drops of solvent on the stem of the volumetric flack above the
graduation mark cause a problem?
5. Which method (1st or 2nd) did you choose to make your solution of sucrose? Why?
6. Where did you find the molar mass (or formula weight FW) of the sucrose?