Key Concepts

Adding power (heating) boosts molecular motion.Increased molecular movement competes through the attraction in between solute molecules and also tends to make them come apart an ext easily.Increased molecular motion causes much more solvent molecule to contact solute molecules and also pull on them with much more force, normally resulting in more dissolving. Due to the fact that different substances room made from various atoms, ions, or molecules, raised temperature will affect their dissolving to various extents.


Students revisit the dissolving M&M activity from great 4. Lock will style an experiment to view if temperature influence the amount of dissolving of the street coating of an M&M.


Students will have the ability to identify and control variables to design an experiment to view whether the temperature that a solvent affects the rate at i beg your pardon a solute dissolves. Students will have the ability to explain, on the molecule level, why increasing temperature boosts the rate of dissolving.


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

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Be sure you and also the students wear effectively fitting goggles. Warn students not to eat the M&M’s.

Materials for Each Group

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

Materials for the Demonstration

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

Have students work in groups to architecture an experiment to investigate whether the temperature of water affect the amount of M&M coating the dissolves.

Remind student of the experiment they go in class 4 in i m sorry they inserted an M&M in water and watched the colored sugar coating dissolve. In that experiment, students provided water and also then alcohol and oil to see if the solvent provided affects the dissolve of the M&M coating.

Ask students:

What could you investigate about M&M’s dissolving in water? If students do not suggest transforming the temperature that the water, ask whether they think the temperature the the water affect the lot of coating the dissolves.

Give each student an activity sheet.

Students will explain their experimental design, record their observations, and answer questions around the task on the activity sheet. The explain It with Atoms & Molecules and also Take It more sections of the activity sheet will either be completed as a class, in groups, or individually, depending on your instructions. Look in ~ the teacher variation of the activity sheet to discover the questions and answers.

Have student groups comment on the following questions:

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

As you visit the groups and listen to your discussions, inspect to watch if students are thinking around variables such as:

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

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

Have student teams share their concepts for compare the effect of temperature on dissolving and consider exactly how each plan controls variables.

As each team presents their plans, have the class identify how each plan controls variables. Some teams may have planned to test M&M’s in hot and cold water however didn’t think about using room-temperature water, too. Encourage all teams to check an M&M in all 3 temperatures of water. The room-temperature water serves as a control and can aid students watch the difference in exactly how temperature affect dissolving.


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

Question come Investigate

Does the temperature of water influence the amount of coating the dissolves from an M&M?

Materials for Each Group

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


Pour cold, room-temperature, and hot water right into the cup so that the water is deep enough to covering an M&M. Place the three cups top top the white paper. Write Cold, Room-temp, and also Hot near its cup.

With the aid of your partners, place a same-colored M&M in the facility of each cup in ~ the very same time. Watch for about 1 minute.


Expected Results

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

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

Record and also discuss college student observations.

Ask students:

Does the temperature of the water affect the amount of colored coating the dissolves from an M&M? exactly how do you know? based on their observations, students have to conclude the the hotter water causes much more dissolving. College student may have actually noticed a greater distinction in the lot of dissolving in between the hot and the room-temperature water than between the room-temperature and also the cold water. If no one comments ~ above this, suggest that over there is a difference.Explain

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

Ask students:

What are the distinctions in the method water molecules relocate in cold, room-temperature, and hot water?Students must remember that water molecules move faster in warm water 보다 in cold. Why execute you think sugar dissolves much better in warm water 보다 in cold water?The reason why street dissolves in ~ a much faster rate in hot water has to do with raised molecular motion. The added energy in the hot water reasons water molecule to move faster and sucrose molecules to vibrate faster. This included movement has tendency to do the bonds between sucrose molecules simpler to overcome. When faster-moving water molecules connect to sucrose molecules, a greater proportion of this sucrose-water interactions have enough power to pull sucrose molecules away from other sucrose molecules, so the rate of dissolving increases.Why execute you think over there is a greater distinction in the quantity of dissolving between the hot and room-temperature water than in between the room-temperature and cold water?There is a greater difference in the rate of dissolving because 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 carry out a demonstration or display a video clip to investigate whether all substances dissolve much far better in warm water than in cold water.

Ask students to do a prediction:

In the activity, you have actually seen that hot water dissolves sugar better than cold water. Perform you think the salt will dissolve much better in hot water 보다 in cold, prefer sugar does?

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

If you choose to perform the demonstration, follow the procedure below.

Question come Investigate

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

Materials for the Demonstration

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

Teacher Preparation

Label two tiny cups salt and two cups sugar. Location 1 tablespoon that salt and also 1 tablespoon of sugar in each of their labeled cups.


Salt in Hot and Cold WaterPlace 25 mL of hot water and also 25 mL the cold water in two separate graduated cylinders. At the very same time, to water one tablespoon of salt right into each i graduated cylinder. Perform not swirl, shake, or stir. Collection these graduated cylinders aside.Sugar in Hot and also Cold WaterPlace 25 mL of hot water and also 25 mL the cold water in two separate graduated cylinders.

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

Compare the quantities of salt and sugar left undissolvedShow students the i graduated cylinders v the salt. Present students the i graduated cylinders with the sugar.

Expected Results

Less street is visible in the hot water than in the cold, an interpretation that an ext sugar dissolves in the warm water 보다 in the cold water. There is no noticeable difference between the quantity of salt that dissolves in the hot water compared to the cold water. This reflects that temperature affect the dissolving of sugar much more than that affects the dissolving of salt.


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

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Tell students that they will plot the solubility that potassium chloride top top a graph provided on the task sheet. Explain that potassium chloride is provided as a salt instead of for human being who should not eat regular salt (sodium chloride.)

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

Ask students:

At what temperature would you say the the solubility of sodium chloride and potassium chloride are around the same?At 0 °C, which substance is the least soluble? at 0 °C, which problem is the most soluble?