Kennedy- LOC lesson, counting atoms, balancing and classify S&D

Law of Conservation of Matter

Watch the video below and add notes to your lab notebook

Law of Conservation of Matter

​What does the word "conservation" mean?

"To conserve"- means to protect something from being harmed or destroyed. In chemistry, this means that the atoms in a physical change and a chemical change are not destroyed, but are still there after the change has taken place.

Multiple Choice

Atoms are ______ during a physical or chemical change.

• created
• destroyed
• rearranged

Multiple Choice

The Law of Conservation of Matter applies to..

• chemical changes only

• chemical changes and physical changes

• physical changes only

Multiple Choice

100g of ice (solid water) melts in a beaker. How many grams of liquid water will there be in the beaker after all of the ice melts?

• 100g because all of the atoms are still there

• 200g because all of the atoms will double

• 150g because all of the atoms will double but some will get lost

• 50g because half of the atoms are destroyed

Multiple Choice

If a total of 6 atoms react together to form a new product, how many total atoms will there be in the product?

• 6 atoms

• 12 atoms

• 0 atoms

• 36 atoms

Multiple Choice

If 5 grams of oxygen reacts with 4 grams of hydrogen, how many total grams of water will be produced?

Which math equation correctly shows the student using the law of conservation of matter to solve this problem?

• 5g + 4g = 9g

• 5g x 4g = 20g

• 5g - 4g = 1g

• 5g / 4 g = 1.25 g

Counting Atoms

As scientists, we need to be able to count the amount of atoms present in each formula in order to know if the equation is balanced and if the law of conservation is being met.

Multiple Choice

How many atoms are present in the following compound?

H₂O

• 2

• 3

• 1

• 0

Multiple Choice

How many atoms are present in the following compound?

3 H₂O

• 3

• 6

• 9

• 1

Multiple Choice

How many atoms are present in the following compound?

2 CaCl₂

• 2

• 4

• 6

• 5

Multiple Choice

How many atoms are present in the following compound?

Mg(NO₃)₂

• 9

• 6

• 2

• 3

Multiple Choice

How many atoms are present in the following compound?

2 Ca₃(PO₄)₂

• 11

• 2

• 26

• 23

Balancing Equations

​In order to meet the law of conservation of matter, there has to be the SAME number of atoms on the left side (reactants) of the arrow (yield sign) as there are on the right side (products)

Dropdown

The reactants are on the ​

Select answer

side of the arrow and the products are on the ​

Select answer

side of the arrow in a chemical equation.

Dropdown

The total number of atoms on the left side of the arrow ​

Select answer

equal the total number of atoms on the right side of the arrow.

Categorize

Options (3)

H₂

O₂

H₂O

Identify what compounds are reactants and what compounds are products in the following equation.

H₂ + O₂ → H₂O

Reactants

Products

Multiple Choice

What coefficients would correctly balance the following reaction?

_H₂ + _O₂ → _H₂O

• 2, 2, 1
• 1, 1, 1

• 2, 1, 2

Multiple Choice

How would you classify this reaction?

2 H₂ + O₂ → 2 H₂O

• Synthesis because there is only one product being made

• decomposition because there is only one reactant and it is breaking down

Multiple Choice

What coefficients would correctly balance the following reaction?

_H₂O → _H₂ + _O₂

• 2, 2, 1
• 2, 1, 1
• 1, 1, 1

Multiple Choice

How would you classify the following reaction?

2 H₂O → 2 H₂ + O₂

• Synthesis because there is only one product being made

• Decomposition because there is only one reactant and it is breaking down

Multiple Choice

What coefficients correctly balance the following equation?

_Na + _Cl₂ --> _NaCl

• 2, 2, 1
• 1, 1, 1

• 2, 1, 2

Multiple Choice

What coefficients would correctly balance the equation below?

_KClO₃ --> _KCl + _O₂

• 1, 1, 1
• 2, 2, 3
• 2, 3, 1

Categorize

Options (15)

C + O₂ -> CO₂

2 H₂ + O₂ -> 2 H₂O

Fe + S -> FeS

Ca + Cl₂ -> CaCl₂

N₂ + 3H₂ -> 2NH₃

2Mg + O₂ -> 2 MgO

2Al + 3Cl₂ -> 2 AlCl₃

2H₂O -> 2H₂ + O₂

CaCO₃ -> CaO + CO₂

2NaCl -> 2Na + Cl₂

2KClO₃ -> 2KCl + 3O₂

2H₂O₂ -> 2H₂O + O₂

Mg(OH)₂ -> MgO + H₂O

2AgBr -> 2Ag + Br₂

2NH₄NO₃ -> N₂ + 4H₂O + O₂

Classify the following balanced equations as either synthesis (one product on right side) or decomposition (one reactant on left side)

Synthesis

Decomposition