Year 7 Science · Unit 2 · Lesson 17

Solutions

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Learning Goals

Order the steps

Number the events from 1 to 6 to show the correct order of what happens when sugar dissolves in water at the particle level. Event 1 = what happens first.

OrderEvent
Every sugar particle is surrounded by water particles — the solution looks clear and uniform.
Water particles knock individual sugar particles loose from the surface of the grain, one at a time.
The freed sugar particles slip into the gaps between water particles.
A solid sugar grain sits in the water — its particles are packed tightly together.
Water particles begin bumping into the sugar grain from all sides.
The dissolved sugar particles spread evenly throughout the whole liquid.

Because… chain — temperature and dissolving

Fill in the missing effects. Each cause leads to the next step in the chain.

Temperature of the water increases
Solvent particles move faster
More collisions between solvent and solute particles
More solute particles dissolve per second

Overall outcome:

1. A student keeps adding salt to a glass of water and stirring. After a while she notices that salt crystals are sitting at the bottom of the glass even though she keeps stirring. What has happened? Use the word saturated in your answer.

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2. A sports drink contains sugar and electrolytes dissolved in water. Name the solute(s) and the solvent in this drink. If you drink half the bottle and then refill it with water, is the drink now more dilute or more concentrated? Explain.

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Wrap Up

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