Question

Properties of water to test at home:

Experiment 1

Materials needed – one paper clip and a glass of water

Procedure: place a paper clip (laying flat) on the surface of the water and observe.

Observations: What happened when you placed the paper clip on the surface of the water?

Procedure: Place the paper clip long ways (up and down) onto the surface of the water.

Observations: What happened when you placed the paperclip long ways on the surface of the water?

Paper clips are made from iron metal (density = 7.87 g/mL). Explain (using the properties discussed in the previous chapter) why you saw a difference when you placed the clip in the water long ways.

What unique property of water did you observe here?

Experiment 2:

Materials: a glass of water and some ice cubes.

Procedure: Fill a glass completely full of water (let some spill over the top so that you know it is full).

Observations: Look across the top of the glass of water. What do you notice about the water level compared to the level of your glass?

Explain what is happening at the top of the glass of water.

Procedure: Place an ice cube in the glass of water.

Observations: What happened when you placed the ice cube in the glass of water?

Explain your observations in part e using what you know about density.

Now, using your knowledge of the properties of states of matter (gas, liquid, solid), explain what would happen to most other substances when you place a solid phase and a liquid phase together.

What unique property of water did you observe here?

Explain how this might be useful for aquatic life in cold temperatures.

Experiment 3

Materials: a glass of water, an empty glass and some paper towels

Procedures:

Twist a couple of pieces of paper towel together until it makes something that looks like a rope.

Place one end of the paper towel into the glass that is full of water and the other end into the empty glass.

Observations: Immediately upon placing the paper towel into the glass of water, what do you observe?

Procedure: Leave the experiment as is and wait 10-15 minutes.

Observations: What has happened during the elapsed time?

What do you think would happen if you left the set-up over night?

What interactions are occurring here that can explain your observations? Hint, adhesive forces and cohesive forces... these are defined in your text or on the internet using your favourite search engine. The structure of paper towel (cellulose) might be of some assistance here. I have given that below. In this structure, the dotted lines represent sites for hydrogen bonding. The waved lines mean the molecule continues in a long chain.

What unique property of water did we observe in this experiment?

Explain how plants (primarily made of cellulose) drink water.

Propose an experiment to test your explanation above.

Explain how blood moves through vessels (structure similar to cellulose) in our extremities (hands and feet... or far away from the pumping heart).

Answer 1

Experiment 1

Observations:

• When the paper clip is placed on the surface of water, it floats. The paper clip doesnot sink and remians on the surface of water.
• When the paper clip is placed longways in water, the paper clip sinks in the water as opposed to floating when it was placed horizontally.
• When the paper clip is placed horizontally on water, the surface tension of the water stops it from sinking into the water, even though the density of paper clip is much higher than that of water (1g/ml). However, when the paper clip is dropped longways in water, the clip hits the surface of water hard enough to break the surface tension and thus, sinks to the bottom.
• In this experiment, the property of water observed is - surface tension.