pH Lab Demo

pH Lab Demo

pH: a measure of the concentration of H₃O⁺ ions in a solution

acidic pH < 7

basic pH > 7

neutral pH = 7

pH Indicators

• Changes colors based on the pH of a solution

• In this demo we will be using the Litmus paper as an indicator

• For Litmus Paper: acids turn blue paper red; bases turn red paper blue

Multiple Choice

What will happen when we dip lemon juice (an acid) in the RED litmus paper?

• It will turn blue

• It will stay red

Multiple Choice

What will happen when we dip the BLUE paper in the lemon juice?

• It will stay blue

• It will turn red

Multiple Choice

What will happen when we dip the RED paper into the baking soda (a base)?

• It will stay red

• It will turn blue

Multiple Choice

What will happen when we dip the baking soda into the BLUE paper?

• It will stay blue

• It will turn red

Now we are going to try an identify mystery solutions as an acid or base, using the litmus paper.

Watch the demostrations with Solution A, B and C, then try to classify each as an acid, base or neutral solution.

Open Ended

Based on the two Litmus Paper Tests, do you think Solution A is an acid or a base?

Open Ended

Based on the two Litmus paper tests, what do you think Solution B is?

Open Ended

Based on the two Litmus paper tests, what do you think Solution C is?