3.23 To determine what happens when an acid and an alkali are mixed

Natural sciences

Reactions that occur between different kinds of matter: acids and bases

Educator section

Memorandum

Step 1: It turned blue, because bicarbonate of soda is an alkali

Step 2: No

Step 3: It became lighter

Step 4: It becomes much lighter and lime green

OBSERVATION:

• Neutral

Leaner section

Content

Activity: to determine what happens when an acid and an alkali are mixed [lo 1.2, lo 1.3]

We have already discovered that a neutral solution is neither an acid nor a base.

What can we expect to happen when and acid and a base are mixed together? Let's find out!

• Use a Bromothymol blue solution as indicator
• Other requirements:
• 100 ml white vinegar
• 150 ml bicarbonate of soda solution

STEP 1: Add a few drops of the bicarbonate of soda solution to the

Bromothymol blue indicator.

What do you observe?

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STEP 2: Add half of the vinegar to the bicarbonate of soda solution

Does this make the solution neutral?

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STEP 3: To determine this, you have to add drops of the mixture to the Bromothymol blue indicator.

What do you observe?

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STEP 4: If no change has occurred, add half of the remaining vinegar to the bicarbonate of soda solution and repeat step 3.

STEP 5: Test the solution again and repeat steps 3 and 4 until there is a change.

What do you observe?

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OBSERVATION:

• The vinegar and bicarbonate of soda formed a________________________ solution. It is neither an acid nor a base.

The process by which acids are destroyed by bases, or bases by acids, is called NEUTRALISATION.

Assessment

Learning Outcome 1: The learner will be able to act confidently on curiosity about natural phenomena, and to investigate relationships and solve problems in scientific, technological and environmental contexts.

Assessment Standard 1.2: We know this when the learner conducts investigations and collects data: organises and uses apparatus/equipment or sources to gain and record information;

Assessment Standard 1.3: We know this when the learner evaluates data and communicates findings: generalises in terms of relevant aspects and describes how the data support the generalisation.