The purpose of this activity is to learn to make sugar solutions that have a specific concentration
of sugar. Your group must work together to create 150 grams of 5%, 10%, 15%, 20%, 25% and 30% sugar water solutions. In order to determine whether you have prepared the solutions correctly, you will tint each solution
a different color, then “stack” all 6 solutions in a graduated cylinder. If the solutions have been prepared correctly, each will have a different density, and create a separate layer. The effect will be that you will create a column of sugar water that will resemble a roll of lifesavers.
Let’s say you had been asked to prepare 150 grams of 8% sugar.
% sugar =
8% sugar =
Solving for X gives 12 grams. You will need to measure out 12 grams of sugar.
How much water will be required? Since the total mass
of the solution
is 150 grams,
150 g – 12 g = 138 grams of water.
In summary: To create 150 grams of 8% sugar water, you will need to combine 12 g of sugar and 138 grams of water.
As a group, you will need to work out the amount of sugar and the amount of water needed to prepare 150 grams of 5%, 10%, 15%, 20%, 25% and 30% sugar water solutions.
Remember that a solute will dissolve most quickly if it is crushed with a mortar and pestle. A magnetic
stirrer can be used to speed
up the dissolving of the sugar.
- Wash bottle
- Food coloring
- 7 beakers
- stirring rod or magnetic stirrer with magnet
- mortar and pestle
- 500 mL separatory funnel apparatus
- ring stand with iron ring
- 1000 mL graduated cylinder
- Develop your own procedure for preparing the six solutions. Tint each a different color.
- Add the least dense solution to the separatory funnel. Partially open the stopcock valve and slowly drain the solution into the bottom of the graduated cylinder. Close the valve before all the solution drains from the separatory funnel so that no air bubbles get into the column.
- Now add the next least dense solution to the separatory funnel. Close the valve just before all of the orange solution drains from the separatory funnel. Add each remaining solution in a similar manner.
- Carefully withdraw the glass tube.
End of Lab Questions
- The least dense layer of sugar water was put into the column first. Why did it end up on the top of the column?
- Draw a diagram of the sugar water column. Label the concentration of each layer. Indicate where an 8% sugar water layer would be expected to be.
- A chemistry student needs to prepare 200. grams of 3.0% salt water. How much water and how much salt must be mixed?
- Which solution has a higher % of sugar?
Solution A: 10.0 g sugar combined with 50. g of water
Solution B: 20.0 grams of sugar combined with 100. g of water
- What is the % by mass of sugar if 75 g of sugar is mixed with 225 g of water? Show your calculation.