STEP 11
To prepare the buffer solution
Open the white sachet containing the effervescent powder (sodium hydrogen carbonate) and pour its content into 150 mL (approx. 5 oz) of cool water. Stir gently with a spoon to dissolve.
Use only cool water to prepare the buffer solution. Do not use any other liquid.
For kids aged 2–6 years, pour away half of the prepared buffer solution before proceeding to Step 2 (keep 75 mL, approx. 2.5 oz).