# Luckau Protocols:KCl

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 KCl Protocol

## Purpose

• In the Clark Lab, 3M KCl is used as a storage solution for the pH meter electrode.
• In the Clark Lab, 2.5M KCl is used as a stock solution for making the PCR Buffer series (A through H)

## To make 125 mL of 3M KCl

### Calculations

• $125 \mathrm{mL} \bullet \tfrac{3 \mathrm{mol}}{\mathrm{L}}\ \bullet \tfrac{\mathrm{L}}{1000 \mathrm{mL}}\ \bullet \tfrac{74.55 \mathrm{g}}{\mathrm{mol}}\ = 27.96 \mathrm{g}$

### Protocol

1. Using digital scale, place 27.96 g KCl powder into weigh boat
2. In 150 mL flask, mix 27.96 g KCl with 100 mL H2O
3. Put flask on hotplate/stirrer with stirbar until dissolved
4. Add H2O to bring volume to 125 mL

• If this 3M KCl is being used for the storage solution for the pH meter electrode, then leave the solution in the Erlenmeyer flask, insert electrode, then wrap with parafilm as best you can to prevent evaporation.

## To make 400 mL of 2.5M KCl

### Calculations

• $400 \mathrm{mL} \bullet \tfrac{2.5 \mathrm{mol}}{\mathrm{L}}\ \bullet \tfrac{\mathrm{L}}{1000 \mathrm{mL}}\ \bullet \tfrac{74.55 \mathrm{g}}{\mathrm{mol}}\ = 74.55 \mathrm{g}$

### Protocol

1. Using digital scale, place 74.55 g KCl powder into weigh boat
2. In 500 mL glass media bottle, mix 74.55 g KCl with approximately 375 mL H2O
3. Put flask on hotplate/stirrer with stir bar until dissolved
4. Add H2O to bring volume to 400 mL

• If this 2.5M KCl is being used as the stock solution for PCR Buffers A-H, then leave the solution in the glass media bottle and store at room temperature on the chemical shelf.