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Lessons in Chemistry

Aired on February 18, 2023

Density Gradient Lemonade Recipe

Density Gradient Lemonade

Evie Kirkwood

The science: Decreasing amounts of sugar lower the density of each subsequent layer. When the layers of liquids are poured carefully, starting with the heaviest, they will remain separated.

  • 2 tall glasses. Narrow glasses work best.
  • Fresh squeezed lemon juice
  • Simple syrup – (bring ¾ c sugar and 2/3 c water to a boil, stirring often. When sugar is
  • dissolved remove from heat and cool. Can be stored for a week or more in refrigerator.)
  • Food coloring, multiple colors
  • Ice
  • Spoon for slow pouring

Prepare the layer mixes. You can make these ahead, but be sure to label them so you know which order to pour them into your glass at the time of serving. You can store them in the refrigerator until you are ready to use them.

  • Bottom, 1st layer – 5 tsp lemon juice + 8 tsp simple syrup + enough water to make ½ cup total liquid
  • 2nd layer – 2 tsp lemon juice + 3 tsp simple syrup + enough water to make ½ cup total liquid
  • 3rd layer – 1 tsp lemon juice + 1 tsp simple syrup + enough water to make ½ cup total liquid
  • Top, 4th layer – 1 tsp lemon juice + ¼ tsp simple syrup + enough water to make ½ cup total liquid.

Before pouring into the glass, add a drop of food coloring into the mixes, a different color for each layer. Stir to mix in the color. You can also leave out the food coloring from ONE of the layers.

Pour half of the Bottom layer liquid into each glass. Add several ice cubes. Turn a spoon upside down so the convex side is up and hold the spoon in the glass, with the tip of spoon just above the first layer of liquid and against the side of the glass. Gently, slowly, pour the second layer liquid onto the back (convex) part of the spoon, raising the spoon up as the level in the glass increases. You can also use an ice cube as an additional buffer pouring the liquid onto the spoon and letting it trickle off an ice cube. If you pour too quickly the layers will mix.

Repeat with the remaining layers, raising the spoon up as the level increases.

The sweetest layer will be on the bottom. After admiring your drink, you could choose to stir it for the best taste.

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