Objective: To explain how to produce percent solutions.

Safety Considerations: To avoid accidental overdose, always label all containers

Materials To Add To Your Lab Bench:

Procedure: 50 mL of 70% EtOH from 100% Ethanol*

(Note :Before you begin make sure you obtain pure water)

Step 1: Calculate the desired volume of starting solution needed to make the final percentage.

Example: A 70% EtOH solution from 100% EtOH

                        100%/50mL = 70%/x mL

                               100%*x = 50mL*70%

                               100%*x=3500mL%

                                          x=35mL EtOH

Step 2: Calculate the desire amount of water to get a total volume of 50mL

                          50 mL - 35mL EtOH = 15 mL dH₂O

Step 3: Measure 35mL of 100%EtOH and 15mL of dH₂O using a 100mL graduated cylinder 

Step 4: Mix the two liquids from step 3 together.
 

(*This would make an extra dry martini)

Procedure:  50 mL of 70% EtOH from 95% Ethanol*

Step 5: Repeat Steps #1 - 4.

Example: A 70% EtOH solution from 95% EtOH

                        95%/50mL = 70%/x mL

                                        x=36.8 mL EtOH

 Obtain the desired final volume (50mL) by adding the appropriate volume of dH₂O (in this case, 13.2mL)
(*This would make a dry martini)

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