Key Concepts

Adding energy (heating) increases molecular motion.Increased molecular movement competes with the attraction in between solute molecules and also tends to do them come apart much more easily.Increased molecular activity causes more solvent molecules to contact solute molecules and also pull on them with more force, normally resulting in an ext dissolving. Since different substances are made from different atoms, ions, or molecules, enhanced temperature will affect their dissolving to different extents.


Students revisit the dissolving M&M task from class 4. They will architecture an experiment to check out if temperature influence the lot of dissolve of the street coating of one M&M.


Students will be able to identify and control variables to style an experiment to view whether the temperature the a solvent affects the rate at which a solute dissolves. College student will be able to explain, ~ above the molecule level, why increasing temperature increases the rate of dissolving.


Download the student task sheet, and distribute one per student as soon as specified in the activity. The task sheet will certainly serve together the “Evaluate” ingredient of each 5-E lesson plan.

You are watching: Which dissolves faster salt or sugar


Be sure you and also the student wear appropriately fitting goggles. Warn students no to eat the M&M’s.

Materials because that Each Group

M&M"s (3 very same color)3 clear plastic cups1 paper of white paperRoom-temperature waterHot water (about 50 °C)Cold water (about 5 °C)

Materials because that the Demonstration

4 graduated cylinders (50 mL)Hot water (about 50 °C)Cold water (about 5 °C)SaltSugarTablespoon2 little cups

Have students job-related in teams to style an experiment come investigate even if it is the temperature the water influence the lot of M&M coating that dissolves.

Remind students of the experiment they did in lesson 4 in which they inserted an M&M in water and also watched the colored sugar coating dissolve. In the experiment, students used water and also then alcohol and also oil to view if the solvent used affects the dissolving of the M&M coating.

Ask students:

What could you investigate around M&M’s dissolving in water? If students carry out not suggest changing the temperature the the water, ask even if it is they think the temperature of the water influence the amount of coating that dissolves.

Give each college student an activity sheet.

Students will explain their experimental design, document their observations, and answer questions around the task on the activity sheet. The define It through Atoms & Molecules and Take It additional sections the the task sheet will either be completed together a class, in groups, or individually, depending upon your instructions. Look at the teacher variation of the task sheet to find the questions and also answers.

Have student groups talk about the adhering to questions:

How might you investigate even if it is the temperature the water influence the lot of coating the dissolves indigenous an M&M? What space the variables in this experiment, and how will certainly you manage them?

As girlfriend visit the groups and also listen to your discussions, inspect to see if students space thinking around variables together as:

Kind that containerAmount that water shade of the M&M’sWhen the M&M’s are inserted in the waterLocation the the M&M’s in every cup

All this variables need to be retained the same. Students should realize that the just variable that should be readjusted is the temperature that the water.

Have student teams share their concepts for to compare the effect of temperature top top dissolving and consider just how each arrangement controls variables.

As each team presents their plans, have the course identify exactly how each arrangement controls variables. Some groups may have actually planned to check M&M’s in hot and also cold water however didn’t take into consideration using room-temperature water, too. Encourage all teams to check an M&M in all three temperatures of water. The room-temperature water serves as a control and can help students view the difference in exactly how temperature affects dissolving.


Have teams place one M&M in cold, room-temperature, and also hot water at the exact same time to investigate the effect of temperature ~ above dissolving.

Question to Investigate

Does the temperature that water affect the amount of coating the dissolves native an M&M?

Materials because that Each Group

3 same-colored M&M’s 3 clean plastic cups1 sheet of white paperRoom-temperature waterHot water (about 50 °C)Cold water (about 5 °C)


Pour cold, room-temperature, and also hot water into the cups so the the water is deep enough to sheathe an M&M. Location the 3 cups on the white paper. Compose Cold, Room-temp, and also Hot close to its cup.

With the help of her partners, ar a same-colored M&M in the center of each cup at the very same time. Watch for about 1 minute.


Expected Results

More color and also sugar dissolve indigenous the M&M in the warm water and less in the room-temperature and also cold water. This method there is much more chocolate visible on the M&M in the warm water than there is in the room-temperature and cold water. The color and sugar in the room-temperature water dissolve somewhere between the cold and also hot water, but are an ext similar come the cold 보다 the hot.

Note: There are actually two processes happening in this activity. The color and also sugar room dissolving in the water yet they are additionally diffusing in the water. The temperature the the water affect the amount of dissolving but it additionally affects the price of diffusion. Student should emphasis on the surface of the M&M to referee the quantity of color and sugar that dissolves.

Record and also discuss student observations.

Ask students:

Does the temperature the the water affect the quantity of colored coating the dissolves from an M&M? how do friend know? based upon their observations, students have to conclude the the name is water causes an ext dissolving. Students may have noticed a greater distinction in the quantity of dissolving in between the hot and the room-temperature water than in between the room-temperature and also the cold water. If no one comments ~ above this, indicate that over there is a difference.Explain

Discuss how distinctions in molecular movement caused much more of the street coating to dissolve in hot than in cold water.

Ask students:

What are the differences in the method water molecules move in cold, room-temperature, and hot water?Students have to remember the water molecule move quicker in hot water than in cold. Why do you think street dissolves much better in hot water than in cold water?The reason why street dissolves in ~ a faster rate in warm water needs to do with boosted molecular motion. The added energy in the hot water causes water molecules to move faster and sucrose molecule to vibrate faster. This included movement tends to do the bonds in between sucrose molecules easier to overcome. Once faster-moving water molecules affix to sucrose molecules, a greater proportion of these sucrose-water interactions have enough energy to traction sucrose molecules far from other sucrose molecules, so the price of dissolve increases.Why execute you think over there is a greater difference in the quantity of dissolving between the hot and also room-temperature water than between the room-temperature and also cold water?There is a greater difference in the price of dissolving since there is a greater distinction in temperature between hot and also room-temperature water (about 30 degrees) than in between room-temperature and cold water (about 15 degrees). Explore

Either perform a show or display a video to inspection whether every substances dissolve much much better in warm water 보다 in cold water.

Ask students to make a prediction:

In the activity, you have seen that warm water disappear sugar far better than cold water. Do you think that salt will certainly dissolve much better in warm water than in cold, choose sugar does?

Project the image Hot and also Cold Water Dissolve Salt vs. Sugar.

If you choose to do the demonstration, monitor the procedure below.

Question come Investigate

Will salt dissolve much better in hot water 보다 in cold, favor sugar does?

Materials because that the Demonstration

4 i graduated cylinders (50 or 100 mL)Hot water (about 50 °C)Cold water (about 5 °C)SaltSugarTablespoon4 little cups

Teacher Preparation

Label two small cups salt and also two cups sugar. Location 1 tablespoon of salt and also 1 tablespoon of street in every of their labeled cups.


Salt in Hot and Cold WaterPlace 25 mL of hot water and also 25 mL that cold water in two different graduated cylinders. In ~ the exact same time, pour one tablespoon of salt right into each i graduated cylinder. Do not swirl, shake, or stir. Set these graduated cylinders aside.Sugar in Hot and Cold WaterPlace 25 mL of warm water and also 25 mL of cold water in two separate graduated cylinders.

At the same time, to water one tablespoon that sugar right into each graduated cylinder. Execute not swirl, shake, or stir. Collection these i graduated cylinders aside.

Compare the quantities of salt and sugar left undissolvedShow students the graduated cylinders through the salt. Show students the i graduated cylinders through the sugar.

Expected Results

Less sugar is visible in the warm water than in the cold, definition that much more sugar disappear in the hot water than in the cold water. Over there is no obvious difference in between the quantity of salt that dissolves in the warm water compared to the cold water. This reflects that temperature affect the dissolving of sugar more than the affects the dissolving of salt.


Plot a solubility curve for potassium chloride and compare it come the solubility the sugar and also salt.

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Tell students the they will certainly plot the solubility the potassium chloride ~ above a graph noted on the activity sheet. Define that potassium chloride is used as a salt instead of for human being who need to not eat continual salt (sodium chloride.)

Table 2. Solubility of Potassium Chloride in Water native 0–100 °C.Temperature (° C)Potassium Chloride

Ask students:

At what temperature would you say the the solubility of salt chloride and also potassium chloride are about the same?At 0 °C, which problem is the least soluble? at 0 °C, which problem is the many soluble?