Aim: To investigate the effects of salt on the density of water (and therefore the ability to float an object in said water) and to find the amount of salt needed to float one regular egg in a glass of water.
Research: Internet research shows that adding salt to water increases the density, and in turn makes it easier for objects to float. 4-10 teaspoons of salt in 1 glass of water is said to be enough to make one egg float (depending on the size of the glass). Multiple sources confirm this answer. Researching the topic also provides reasons as to why an object may float in water with higher density.
Hypothesis: After adding enough (approximately 10) teaspoons of salt to the glass, the egg will rise to the top of the water and float.
Materials:
-1 raw egg
-1 glass of water
-Table salt
-1 teaspoon
-1 tall drinking glass
Experiment design:
Independent variable - Amount of salt
Dependent variable – Flotation of egg
Controlled variables – Same glass, same water amount, same temperature, same egg used.
Method:
1. Place egg in glass of pure water and watch as it sinks to the bottom. If the egg does not sink, find a new egg and repeat the step until the egg sinks to the bottom.
2. Add one teaspoon of salt and stir until all the salt has dissolved. Observe the egg and note any differences in its position.
3. Continue to add salt, teaspoon by teaspoon (stirring each time salt is added) and record your results each time. Add until the egg begins to float and has reached the top of the water.
4. Record what you have observed during the experiment.
Salt (tspn)
Flotation:
0
No flotation – egg sinks immediately.
1
Slight difference, egg does not fall/sink as quickly.
2
Egg’s condition is unchanged.
3
Egg sinks very slowly but does not float.
4
Condition unchanged.
5
Egg is able to stay upright in water for a short period of time.
6
Egg can be suspended