Year 10 Science · Unit 2 · Lesson 12

Concentration and Surface Area

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Learning Goals

Trace the cause-and-effect chain from crushing marble chips to an increased rate of reaction.
Apply surface area concepts to explain real-world phenomena such as flour dust explosions.
Distinguish between factors that affect rate and factors that affect total yield.

Warm Up

Because… chain

Fill in the missing effects in the chain below. The first step is given. Follow the logic through to the final outcome.

Marble chips (CaCO₃) are crushed to a fine powder

→

Total surface area of the CaCO₃ increases dramatically

→

More CaCO₃ particles are exposed to HCl

→

Number of collisions per second increases

→

Does the total amount of CO₂ eventually produced change? Explain:

Your Turn

Real-world context

In 2003, a grain storage facility near Wollongong, NSW, experienced a catastrophic explosion when fine wheat flour dust became suspended in air. In contrast, whole wheat grains stored in adjacent bins did not ignite. The disaster led to strict dust management regulations in Australian grain handling facilities under the Work Health and Safety Act 2011. Both flour dust and whole grain contain the same combustible organic material, only the particle size differed.

(a) Using your knowledge of surface area and reaction rate, explain why suspended flour dust ignited explosively while the whole grain did not.

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(b) A safety officer recommends keeping dust concentrations in the air below a critical level. Using collision theory, explain how both surface area (dust particles) AND concentration (dust in air) contribute to the explosion risk.

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Show What You Know

1. A crushed antacid tablet dissolves faster in stomach acid than a whole tablet of identical mass. Explain this observation and state whether the total amount of antacid that dissolves will be different.

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Wrap Up

In one sentence, what was the main idea of this lesson?