Teks 8.6BE Review

How to count atoms in a chemical formaula.

• You already know how to read SUBSCRIPTS

• A subscript tells us how many of each atom there are

Coefficiant

• The large number in FRONT of the symbol. You have to multiply this number by all of the subscripts.

• 4 Iron Atoms

• 6 Oxygen Atoms

Multiple Choice

How many Hydrogen are in 4H₂O?

• 6
• 8
• 2
• 4

Multiple Choice

How many Magnesium are in 10MgCl₂?

• 10
• 5
• 20

Multiple Choice

How many atoms are there TOTAL in:
H₂SO₄

• 6
• 5
• 7
• 3

Multiple Choice

How many total POTASSIUM atoms are in this formula?

• 8

• 2

• 4

• 12

Multiple Choice

How many atoms of Iron are in this compound?

• 1

• 2

• 3

• 4

Multiple Choice

How many nitrogen atoms are there?

• 4

• 8

• 10

• 20

Multiple Choice

How many phosphorus atoms are there?

• 0

• 1

• 3

• 4

Multiple Choice

How many atoms of carbon are there?

• 0

• 1

• 2

• 3

Multiple Choice

How many Nitrogen atoms are in (NH₄)₂CrO₄?

• 1

• 2

• 8

• 16

Multiple Choice

How many Oxygen atoms are in Al₂(SO₄)₃?

• 4

• 12

• 7

• 24

Multiple Choice

What is HCl
(hydrochloric acid) made up of?

• 1 hydrogen, 1 carbon,  1 Iodine
• 1 hydrogen & 2 carbons
• 1 hydrogen & 1 chlorine
• 1 hydrogen & 2 chlorine

Multiple Choice

What is H₂SO₄ 
(Sulfuric Acid) made up of?

• 2 hydrogen, 1 sulfur, 4 oxygen
• 1 hydrogen, 2 sulfur, 4 oxygen
• 2 hydrogen & 4 sodium
• 1 hydrogen & 6 sodium

Multiple Choice

The blue numbers in the image below represent ________

• I don't know, and don't want to try
• coefficients
• subscripts
• none of the answers are correct

Multiple Choice

Which of the following chemical formulas contains exactly 4 hydrogen atoms?

• CH₃COONa

• NH₄OH

• CH₃CH₂Cl

• CH₃CHO

Multiple Choice

C₃H₅(NO₃)₃

• C = 3, H = 5, N = 3, O = 9

• C = 3, H = 5, N = 1, O = 9

• C = 9, H = 15, N = 3, O = 9

• C = 9, H = 15, N = 1, O = 3

Parts of Chemical Equation/Formula

• Elements- Tell the elements in the molecule. (These are highlighted in yellow)

• Coefficient- tells us the number of molecules that are present in a chemical reaction. (These are highligted in red).

• Subscripts-tells us the number of atoms of each element in the molecule. (These are highlighted in purple)

Parts of the Chemical Equation

• Reactants-are elements or compounds on the left side of a chemical equation that enter a chemical reaction. 

• Products-are elements or compounds on the right side of a chemical equation that are produced by a chemical reaction. 

• Arrow-  signifies that the reactant yields (equals, produces, turns into). 

Multiple Choice

What is the right part of a chemical equation called...
2H_{2 +} O₂ --> 2H₂O

• Reactants
• Products 
• Yields 
• Chemical Equation 

Multiple Choice

Identify the Reactants in this equation.

• A

• B

Multiple Choice

What is the part of the chemical equation in green called? 
Fe + S --> FeS

• products
• reactants
• yield
• chemical formula

Multiple Choice

Which of the following is the general form of a chemical equation?

• Reactants → Products
• Products + Reactants = 100%
• Reactants = Products
• Products → Reactants

Multiple Choice

The substances at the beginning of a chemical reaction are called the ____

• product
• yield
• chemical symbol
• reactants

Balanced Equations

• Follow the Law of Conservation

• Have the same number and type of atoms on both sides

• They just get rearranged!

Multiple Choice

Balanced or Not?

H₂ + O₂ ---> H₂O

• Balanced

• Not

Multiple Choice

Balanced or not?

N₂+6H₂ ----> 2NH₆

• Balanced

• Unbalanced

Multiple Choice

How does a balanced chemical equation satisfy the Law of Conservation of Mass?

• During a chemical reaction, matter is destroyed.

• During a chemical reaction, the total number of atoms increases.

•  During a chemical reaction, one or more new substances are formed.

• During a chemical reaction, the total amount of matter stays the same.

Multiple Choice

Maria fills a bowl with 200 g of water. She puts the bowl of water in the freezer, and the water freezes. Which will most likely be the mass of the frozen water?

• 50 g
• 100 g
• 200 g
• 400 g

Multiple Choice

In a reaction A + B ----> C,  reactant A has 5g and product  C has 9g. How many grams should reactant B have? 

• 4g
• 5g
• 9g
• 14g

Multiple Choice

A chemical reaction is balanced when

• both sides have the same elements
• Both sides have the same  number of atoms
• Same subscripts
• Same coefficients

Multiple Choice

In which of the following equations is the law of conservation of mass supported? 

• 4P₂ + 10O₂ --> 2P₂O₅

• SO₂ + O₂ --> S₂O₅

• 2Al +3HCl --> 2AlCl₃ +3H₂

• 2H₂O --> 2H₂+O₂

Multiple Choice

Which best represents a balanced equation?

• 120 grams of carbon plus 20 grams of oxygen → 200 grams of carbondioxide
• 120 grams of carbon plus 50 grams of oxygen → 200 grams of carbondioxide
• 120 grams of carbon plus 80 grams of oxygen → 200 grams of carbondioxide

Multiple Choice

Which equation is balanced according to the Law of Conservation of Mass?

• NaCl + Mg →
   MgCl₂ + Na
• 2NaCl + Mg → MgCl₂ + Na
• 2NaCl + Mg →
  MgCl₂ + 2Na

Multiple Choice

Matter can not be created nor destroyed: it can only be

• Destroyed a little bit
• Invisible
• Transformed, changed
• None of the above

Multiple Choice

How many grams of OXYGEN would be needed to show conservation of mass in the example below?

• 100 g

• 93 g

• 7 g

• 0 g

Multiple Choice

How many grams of CHOCOLATE POWDER are shown in the example of conservation of mass below?

• 450 g

• 465 g

• 0 g

• 15 g

Multiple Choice

Which Chemical Equation is Balanced?

• CH₄+O₂------CO₂+2H₂O

• H₂+O₂-----2H₂O₄

• 4Al+3O₂-----2Al₂O₃

Multiple Choice

Which is Chemical Equation is Balanced?

• CH₄+O₂------CO₂+2H₂O
• H₂+O₂-----2H₂O₄
• 4Al+3O₂-----2Al₂O₃

Multiple Choice

In the equation shown, what are the reactant(s)?

• N₂ + H₂

• NH₃

Multiple Choice

A solid mass of 25 g is mixed with 60 g of a solution in a closed system. What is the mass of the products?

• 85 g

• 35 g

• 60 g

• 25 g

Multiple Choice

If a reaction starts with a total 75g of reactants it should produce 

• a total of 40g of products
• a total of 75g of products
• a total of 180 g of products
• None of the above

​Signs of a Chemical Change

Can Green Lizards Teach Physics

• Color

• Gas Production (Bubbles/Fizzing)

• Light Production

• Temperature Change (up or down)

• Precipitate  (liquid + liquid = solid)

• a change in the physical and chemical properties

• one or more NEW substances are formed

Chemical Change

• a change in physical properties only, such as size, shape, or state

• NO new substance is formed

​Physical Change

Review of Physical and Chemical

Changes in Matter

Multiple Choice

Which process is a sign of a chemical change?

• a rotting potato gives off a bad smell

• a melting block of ice leaves a large puddle

• a cloud quickly changes shape when blown by the wind

• a plaster statue breaks when it falls on the floor

Multiple Choice

Which process is an example of of a physical change?

• ice melting

• milk souring

• metal rusting

• wood burning

Multiple Choice

A tire is inflated with air.

• Chemical Change
• Physical Change

Multiple Select

Which of the following are examples of a Chemical Change?

• Iron Rusting

• Gas Burning

• Breaking a glass

• Boiling water

• Burning Wood

Multiple Choice

What is a chemical change?

• Forming a new substance

• When two or more substances combine to make a greater one

• When two or more substances combine to make a new chemical substance

• Combing substances

Multiple Choice

Which is an example of a chemical change?

• baking a cake
• freezing water
• crushing a can
• breaking an egg

Multiple Choice

Which example best describes a physical change?

• iron rusting
• charcoal burning
• an ice cube melting
• a marshmallow burning

Multiple Choice

Dissolving sugar in your coffee is a ____ change.

• chemical change

• physical change

Multiple Choice

Which one shows that a chemical reaction has occurred?

• dissolving

• melting

• formation of a gas

• bending

Multiple Choice

Which of the following IS a physical change?

• Getting a haircut
• Rusty metal
• sour milk
• A compound

Multiple Choice

a copper penny turning greenish after a few years.

• Chemical Change
• Physical Change