Investigation 7: Melting and Dissolving

December 10 and 11

Warm Up

• Compare and contrast melting and dissolving.

Melting

• Melting is adding KE to a substance to change it from solid to liquid.• Physical

change• Requires heat

Dissolving

• Dissolving is when a solid is placed in a liquid and particles of the solid break away into the liquid.

• Not a phase change• This is a physical

change• Requires liquid

Learning Target

I can demonstrate that the temperatures at which phase changes occur are different for different substances.

Melting and Dissolving Experiment

• Summarize the m&m experiment• What part melted?• What part dissolved?

Calculating Calories

Kenielle wanted to eat a bowl of soup. He added 50 mL of water to the ramen noodles. It was 20 C. He needed to heat it up to 70 C. How many calories did it take to heat it up?

QUIZ

• You will get a Clicker• Do not touch any buttons until I give you

instructions.• If you do not follow instructions, you will take

the quiz on paper.

Page 115: Melt 3 Materials

• Predict if margarine, wax, and sugar will melt. • With your group discuss a procedure to test

your prediction.

Page 115: Melt 3 Materials

• Student D will be in charge of materials. • Make sure you record your observations in the

table.

Procedure

1. Put butter, wax, spoonful of sugar into a paper cup each.

2. Fill ½ Liter container with hot water about 1/3 of way up.

3. Place thermometer in water.4. Place cups in water.5. Observe for 5 minutes. 6. Record observations.

CHAMPSC- Only with your group. Only on topic.H- Check in book, notes, and ask your group members. Raise your hand if you have a questionA- Completing lab and table on pg 115.M- NoneP- All students working on lab. Success for all!!!

Observations

• Margarine• Wax• Sugar

Melting of Margarine

• Solid changed to liquid• Heat energy transfers to the margarine

and particles gain KE.• They vibrate more and more until they

start to move around and past one another. • When all the particles are moving, the

margarine is melted and now liquid.

Melted Margarine in Cold Water

• What would happen to the particles if melted margarine were put in cold water?– Energy would transfer from the margarine

particles to the cold water, reducing the KE of the particles.

– The particles would slow down, stop moving, and it would change back to a solid.

Wax Particles

• What happened to the wax particles in the hot water?– Heat energy transfers to the wax and the particles

gain KE.– They vibrate more and some start to move around

each other causing the wax to get soft.

Sugar Particles

• What happened to the sugar particles?– Heat energy transfers to the sugar and the

particles gain KE.– They vibrate more but not enough to change

phases to liquid.

Green Textbook page 42

• Read pages 42 to 48

• Answer questions on page 119 in science notebook

Exit slip

•Why did the wax not change phases and turn to a liquid when put over hot water?

CHAMPSC- NoneH-Raise your handA- Sitting up, recording your answersM-NoneP- All students working on answeringSuccess for all students!

CHAMPSC- NoneH-Raise your hand if you have a question.A- Sitting up, working on quizM-None P- All students sitting quietly correcting quiz.Success for all students!

CHAMPSC- Only at your group.H-Raise your hand if you have a question.A- Sitting up, working on answers. M-None. P- All students working on pages 97 and 99.Success for all students!