Phys/Chem Changes 1
Is dissolving a physical or chemical change?
Physical Change
When paper catches on fire, does it go through a physical change or a chemical change?
Chemical Change
When a substance is added to water, what has to happen to the solute for it to become a solution?
It must dissolve
Does room temperature water or hot water cause a higher rate of dissolution?
Hot Water
What would you have to do in order to dilute a solution?
Add more solvent
Which statement describes a physical change?
A) A piece of paper burning.
B) A bike chain rusting.
C) Silver melting into a mold for a ring shape as it hardens.
D) A bowl turning turning black when exposed to air.
C) Silver melting into a ring shape as it hardens.
Is burning toast an example of a physical change or a chemical change?
Chemical Change
Aqueous solutions may have color or be colorless.
True or False
True
Does stirring occasionally or stirring constantly cause a higher rate of dissolution?
Stirring constantly
What do you add to a solution in order to get a higher concentration?
Solute
Jojo is looking in her cousin's apartment and is identifying things as chemical or physical changes. Which of the following is a chemical change?
A) Jojo's cousin is watching candle wax melt.
B) Jojo's aunt chops onions for dinner.
C) Jojo's niece mixes koolaid with water.
D) Jojo's uncle burns the biscuits while cooking.
D) Jojo's uncle burns the biscuits while cooking.
T/F. Gas being released when substances are mixed is evidence of a chemical change.
True
What does the term insoluble mean?
The solute will not dissolve
A mom wants to make Hot Chocolate for her two kids at home. These were the steps she took to make the Hot Chocolate.
Step 1 - Put room temperature water into a cup.
Step 2 - Heat the water in the cup through the microwave.
Step 3 - Put the Hot Chocolate powder into cup.
Step 4 - Stir the powder in the cup.
If the mom wanted the hot chocolate to be sweeter and added sugar, at which step would the sugar dissolve the fastest?
A) Step 1
B) Step 2
C) Step 3
D) Step 4
B) Step 2
Adding more solvent to a solution makes it __________.
dilute
Which substance went through a chemical change?
Foil = No change
Pencil = Catches Fire
Candle = Melting
Water = Evaporating
Pencil = Catches Fire
List 3 physical properties.
Color, Shape, Size, Texture, etc.
Would a large aspirin pill or 2 small aspirin pills have a higher rate of dissolution? Explain.
2 small aspirin pills.
Explain - surface area
What steps will help make the highest rate of dissolution?
A) Cold water, crushed sugar, no stirring
B) Room temperature water, sugar cube, stirring
C) Hot water, sugar cube, stir occasionally
D) Hot water, crushed sugar, stir constantly
D) Hot water, crushed sugar, stir constantly
What method will help dilute a solution the MOST?
A) Add more solvent to a solution.
B) Stir the solution until the solvent has been dissolved.
C) Add more solute to the solution.
D) Heat a solution to make it boil.
A) Add more solvent to a solution.
A flask was filled with water. The following observations were made.
I. Bubbles formed in the water
II. The bottom of the flask began to feel hot
III. A precipitate was formed.
IV. They saw the water begin to dissolve.
Which observation was a physical change?
IV. Water began to dissolve
Candy companies melt chocolate and pour it into shaped molds then let it cool to solidify again.
What type of change is this:
Physical or Chemical
Physical
A class performs an experiment on different substances. They observed what they found.
Substance 1: Orange powder - Water turned orange and cannot see any powder floating
Substance 2: Blue liquid - Blue liquid droplets formed together and floated on top of the water.
Substance 3: Red solid - Red solid disappeared and water turned completely red.
What substance most likely formed a solution?
A) 2 only
B) 2 and 3
C) 1, 2, 3
D) 1 and 3
D) 1 and 3
A teacher is measuring the rate of dissolution when temperature and stirring is involved with a solid. The temperatures and stirring were as follows:
1st Product: Temp (C) - 10 degrees / No Stirring / Dissolve Time: 160 sec
2nd Product: Temp (C) - 10 degrees / Continual Stirring / Dissolve Time: 130 sec
3rd Product: Temp (C) - 20 degrees / No Stirring / Dissolve Time: 40 sec
4th Product: Temp (C) - 20 degrees / Continual Stirring / Dissolve Time: 30 sec
Based on the evidence, what can be concluded?
A) Higher temp has an effect but stirring has a stronger effect.
B) High temp and stirring has the same effect on rate of dissolution.
C) Stirring has no effect and high temp does.
D) Higher temp and stirring both effect rate of dissolution, but temp has a stronger effect.
D) Higher temp and stirring both effect rate of dissolution, but temp has a stronger effect.
Amanda has two beakers. She fills both beakers with the same amount of solute. Both beakers have 60g of NaCl with different amounts of water.
Beaker A - is filled with 100mL of water
Beaker B -is filled with 50 mL of water
Which of the following statements are true?
A) Beaker A is more concentrated than Beaker B.
B) Beaker B is more concentrated than Beaker A.
C) Concentration cannot be determined.
D) Both beakers have the same amount of concentration.
B) Beaker B is more concentrated than Beaker A.