Ocean Acidification Is a pH Calculation

Lab Brief #3

🎯 Your mission

Run the experiment. Find out what really happens.

⚡ The twist

Every species solves the same problem differently.

What you'll learn

Dissolved carbon dioxide forms carbonic acid, which releases hydrogen ions and lowers pH. Surface ocean pH has fallen from about 8.2 to 8.1 since industrialisation, which sounds trivial until you remember the scale is logarithmic: that drop is close to a 30% rise in hydrogen ion concentration. Those extra hydrogen ions react with carbonate ions, leaving fewer available for the calcium carbonate that corals, molluscs and some plankton build with.

Key words

carbonic acid
The weak acid formed when carbon dioxide dissolves in water, releasing hydrogen ions and lowering pH.
calcium carbonate
The mineral corals and shellfish build shells and skeletons from, whose raw material is depleted as pH falls.

Make a hypothesis first

Before you watch: what do you think it'll do?

Say your guess out loud — then find out if you were right.

Get ready

🧰 What you need

universal indicator
beakers
straws
eggshell or chalk
balance
pH chart

Get ready

⚠️ Safety first

Blow out through the straw only, never suck in.
Wear eye protection and wash your hands when you finish.

Step 1 of 4 · Read

Think about what you just learned: say what "carbonic acid" and "calcium carbonate" mean in your own words before you start.

Step 2 of 4 · Do

Bubble exhaled breath through water containing universal indicator and record the colour change against a pH chart. Then place clean eggshell or chalk pieces in water of three different pH values and compare their mass loss after a week.

Step 3 of 4 · Observe

Record what actually happened, including anything that did not match what you expected.

Step 4 of 4 · Record

Write a conclusion that answers the question this lesson opened with, and state your uncertainty.

Question 1 of 3

A pH drop from 8.2 to 8.1 corresponds to a hydrogen ion rise of roughly:

How sure are you?😐 maybe

Question 2 of 3

Carbon dioxide dissolving in seawater forms:

How sure are you?😐 maybe

Question 3 of 3

Acidification harms corals because hydrogen ions reduce the availability of:

How sure are you?😐 maybe

Mind = blown

🌳 Trees can talk to each other through underground fungus networks.

Nice work!

You got 0 of 3 right.

Next: Whole-Life Accounting Changes the Answer All lessons

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✨ More to explore

🌍 Where you see this in real life: This is why plants grow toward windows and why scabs form.

🏆 Stretch challenge (try it this week): Watch a plant or pet for 5 minutes today and write down what you noticed.

👨‍👩‍👧 For the dinner table: “Tell me something you noticed about your own body today.”

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Ocean Acidification Is a pH Calculation

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