Osmosis egg lab
01 // Question
How does the liquid an egg soaks in change its mass after 24 hours?
A testable question names one thing you change and one thing you measure.
02 // Variables
Independent
Liquid the egg soaks in- Distilled water
- Corn syrup
Dependent
Change in egg mass- Grams, to 0.1 g
- Percent change
03 // Hypothesis
IF a shell-less egg soaks in corn syrup for 24 hours, THEN its mass will decrease, BECAUSE water moves out through the membrane toward the side with more dissolved sugar.
04 // Procedure
1. Remove the shell
Cover each egg with vinegar for 24 to 48 hours until the shell is gone.
2. Weigh
Rinse, blot dry and record the starting mass to 0.1 g.
3. Soak
Put each egg in 250 mL of its liquid for 24 hours at room temperature.
4. Blot and reweigh
Lift out with a spoon, blot gently and weigh on the same scale.
5. Calculate
Find the change in grams and the percent change for each egg.
05 // Data table
| Liquid | Start (g) | After 24 h (g) | Change (g) | % change |
|---|---|---|---|---|
| Vinegar (shell step) | ____ | ____ | ____ | ____ |
| Distilled water | ____ | ____ | ____ | ____ |
| Corn syrup | ____ | ____ | ____ | ____ |
Formula % change = (mass after − start mass) ÷ start mass × 100
06 // What to expect
Eggs in vinegar and distilled water gain mass. The egg in corn syrup loses mass and wrinkles, because the sugar molecules are too large to cross the membrane easily.
Water moves from the side with less dissolved sugar to the side with more, through the egg's semi-permeable membrane, until the concentration is closer to equal on both sides.
07 // Lab notes
- Blot each egg before weighing. Syrup left on the membrane adds mass you did not measure.
- Use the same scale for every weighing and record to 0.1 g.
- Safety. Raw egg can carry Salmonella. Wear gloves, wash hands and wipe the bench afterward.
- Safety. Vinegar stings eyes. Keep goggles on while you pour it.
- The syrup egg turns floppy. Lift it with a spoon so the membrane does not tear.
08 // Remember
Water moves. Sugar mostly stays put. The scale tells you which way the water went.
09 // Questions people ask
Why does the egg in corn syrup lose mass?
Corn syrup has much more dissolved sugar than the inside of the egg, so water moves out of the egg through its membrane toward the higher sugar concentration, a process called osmosis.
How long does it take to remove an egg shell with vinegar?
Usually 24 to 48 hours. The acetic acid in vinegar dissolves the calcium carbonate shell, leaving just the soft membrane behind — swap the vinegar once partway through for a faster, cleaner result.
What is the independent variable in the osmosis egg lab?
The liquid the egg soaks in (typically distilled water versus corn syrup) is the independent variable. The dependent variable is the change in the egg's mass.