1st 6 weeks Review

Physical Changes (Term)

• Are easily reversible, have no new products, and are often just a change of state of matter (Definition)

• Examples include:

• Solid to liquid

• Liquid to gas

• Gas to liquid

• Liquid to solid

Multiple Choice

What is an example of a physical change?

• baking brownies

• explosion

• cutting paper

• rust on metal

Multiple Choice

Is baking a cake a physical or chemical change?

• Physical

• Chemical

Multiple Choice

Chopping wood

• physical change

• chemical change

Multiple Choice

Mixing different colored marbles

• physical change

• chemical change

Multiple Choice

Firework

• physical change

• chemical change

Multiple Choice

Making eggs for breakfast

• physical change

• chemical change

Multiple Choice

Burning wood

• physical change

• chemical change

The Rate of Dissolution

One factor that affect the rate of dissolving is:

Stirring

• Stirring a solute into a solvent speeds up the rate of dissolving because it helps distribute the solute particles throughout the solvent. .

• For example, when you add sugar to iced tea and then stir the tea, the sugar will dissolve faster

• If you don’t stir the iced tea, the sugar may eventually dissolve, but it will take much longer.

One factor that affect the rate of dissolving is: Temperature

• The temperature of the solvent is another factor that affects how fast a solute dissolves. Generally, a solute dissolves faster in a warmer solvent than it does in a cooler solvent because particles have more energy of movement. 

• For example, if you add the same amount of sugar to a cup of hot tea and a cup of iced tea, the sugar will dissolve faster in the hot tea.

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One factor that affect the rate of dissolving is: Particle Size

• Smaller particles have greater surface area. With greater surface area, there can be more contact between particles of solute and solvent

• If you put granulated sugar in a glass of iced tea, it will dissolve more quickly than the same amount of sugar in a cube, because all those tiny particles of granulated sugar have greater total surface area than a single sugar cube.

  
  

Multiple Choice

True or False

The rate of dissolving of a solute in a solvent is faster when the solute and solvent are stirred.

• True

• False

Multiple Choice

True or False

The rate of dissolving is affected if the solute consists of smaller particles with more surface area.

• True

• False

Multiple Choice

You want to make chocolate milk using Hershey's syrup. How could you speed up the rate of the syrup dissolving in your milk?

• Put the syrup in the fridge to cool before putting it in the milk

• Put the syrup in the milk and let it sit

• Increase the amount of syrup you put into the milk

• Warm up the syrup before putting it into the milk

Multiple Choice

Jackson is making dinner and is trying to dissolve salt into a pot of water. The salt is dissolving slowly. What should Jackson do to speed up the rate of dissolving?

• He should put larger salt particles in the water.

• He should heat the water to a higher temperature.

• He should completely stop stirring the pot of water.

• He should slow down the speed he is stirring the pot.

Multiple Choice

What combination would dissolve a solid solute the fastest?

• high temperature, no stirring

• no heat, no stirring

• sugar cube, no heat

• high temperature, stirring

Multiple Choice

Which of the following statements is true about how using smaller salt crystals would affect the rate of making a salt solution in water?

• Smaller crystals increase the surface area and slow down dissolving.
• Smaller crystals decrease the surface area and speed up dissolving.
• Smaller crystals increase the surface area and speed up dissolving.
• Smaller crystals decrease the surface area and slow down dissolving.

Multiple Choice

The smaller the particle size the faster the rate of dissolution (rate of dissolving).

• True

• False

Multiple Choice

Stirring the solution increases the rate of dissolution (rate of dissolving).

• True

• False

By crushing the solute to smaller pieces the amount of surface area for the solute to contact the solvent INCREASES.

The more solute/solvent interactions that occur the faster will be the rate of dissolution!

This is why Kool-aid is such a fine powder!

***Important to note that molecular bonds are NOT being broken, the molecules are just in smaller pieces.

Size of solute - explained

Agitation - Recap

Stirring or agitating a solution increases the amount of solute/solvent interactions mechanically.

Increasing solute/solvent interactions increases rate of dissolution.

This is why you stir the Kool-aid when you add it to the water.

Multiple Choice

What is a substance that is dissolved in another substance? 

• solution
• solute
• solvent
• compound

Multiple Choice

What is a solvent?

• The substance that does the dissolving in a solution.
• The substance that is being dissolved in a solution.
• The mixing of different substances.
• The process in which neutral molecules lose or gain electrons

Fill in the Blank

A aqueous solution means that a salt has been dissolved in _______.

Multiple Choice

The ___ does the dissolving, while the ____ gets dissolved.

• solvent, solute

• solute, solvent

• solute, solution

• solution, solute

Multiple Choice

Which part of the solution does the dissolving?

• solute

• solution

• solvent

Multiple Choice

Which part of the solution is dissolved?

• solute

• solution

• solvent

Elements and Compounds

By Hanadi Mohammed 6/A

​a substance that occurs when atoms of two or more different elements are bonded together.​​

​Example: Suger, table salt, water, carbon dioxide.

Compounds is :-

a substance made of only one type of atom .

Example : ​iron, copper, silver, gold, hydrogen, carbon, nitrogen, and oxygen.

Elements is :-

What ​Is elements and compounds :-

​Then Let's Start The Multiple questions :-

Multiple Choice

What is elements ?

• elements are smallest unit of the matter

• element are the substance that contains two or more type of atom

• element are the substance that contains only one type of atom

• element are the cells

Multiple Choice

What is compounds ?

• Compounds are the substance that contains two or more types of atoms

• Compounds are the substance that contains one types of atoms

- Remember it -

​This is one of an element that represents in periodic table "Hydrogen 2 + Oxygen = Water"

​

This ​is knows as chemical Formula : is a group of chemical symbols and numbers that represent the elements and the number of atoms of each elements that make up of compounds.

Multiple Choice

Which of the following is a compound?

• O₂

• H₂O

• C

• He

Multiple Choice

What is the chemical formula for this picture

• C₂O

• ₂CO

• CO₂

• all non incorrect

Multiple Choice

Write the correct Chemical formula

Red : Oxygen

Blue : Nitrogen

White : Hydrogen

• H₂ON

• OHN₂

• NHO₂

• ₂OHN

Multiple Choice

Is Hydrogen a compound?

• True

• False

Multiple Choice

Is this table correct?

• True

• False

Multiple Choice

What do you think this picture is .........

• Air Molecule

• Nitrogen Molecule

• Water Molecule

• Hydrogen Molecule

Multiple Choice

This picture represents which of the following?

• element

• compound

Multiple Choice

Elements are written with ___ capital letter.

• ONE

• TWO

• TWO OR MORE

Multiple Choice

Which of the following represents an element?

• H₂O
• H₂
• NaCl
• CaCO₃

Multiple Choice

Which of the following represents an element?

• H₂O

• HCl

• NaCl

• Au

• CaCO₃

Multiple Choice

Is water an element or a compound?

• Element
• Compound

Multiple Choice

Is sugar (C₁₂H₂₂O₁₁) an element or a compound?

• Element
• Compound

Multiple Choice

Which of the following is a compound?

• Si

• CO₂

• Cl

• He

• Ti

Multiple Choice

Which of the following is an example of an ELEMENT?

• Water - H2O

• Salt - NaCl

• Neon - Ne

• Methane - CH4

Multiple Choice

Which of the following is an example of a COMPOUND?

• Cobalt - Co

• Ammonia - NH3

• Carbon - C

• Lithium - Li2