Chemical Reactions

Chemical Reactions

Standard CHE 6: The student will demonstrate an understanding of the types, the causes, and the effects of chemical reactions.

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How are chemical reactions expressed in science?

H₂ + O₂ --> H₂O

​Describe this equation in your own words.

​Why are hydrogen and oxygen shown as they are?

​Does anyone know if this equation is balanced?

​Coefficients describe the number of molecules

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Subscripts describe the number of atoms of an element in a molecules

Multiple Choice

Coefficients tell the number of __________ in a formula.

• Molecules

• Atoms

• Elements

• Oxygen

Multiple Choice

A subscript is the small number below the element symbol that tells the number of _______ of that element.

• atoms

• valence electrons

• protons

• elements

Multiple Choice

How many Sodium atoms are in 6NaCl?

• 1

• 12

• 6

Multiple Choice

How many Hydrogen atoms are in 4H₂O?

• 6

• 8

• 2

• 4

Multiple Choice

A ______ is a number written in front of a chemical formula.

• Coefficient

• Subscript

• Exponent

• Coordinator

Multiple Choice

Describes the number of molecules in a compound and is used to balance a chemical reaction. 

• coefficient 

• subscript

• superscript

• SI unit

​Word Equations describe the reaction with words

​Skeleton Eqn's aren't balanced yet!

​Zinc metal reacts with hydrochloric acid to produce aqueous zinc(II) chloride and hydrogen gas.

​Aqueous Potassium Iodide reacts with Aqueous lead (II) nitrate to produce Aqueous potassium nitrate and solid lead(II) iodide.

Multiple Choice

In this reaction, the products are...

• oxygen and water

• carbon dioxide and water

• oxygen and methane

• methane and carbon dioxide

Multiple Choice

In this reaction, the products are...

• solids

• liquids

• gases

• dissolved in water

Multiple Choice

the starting materials in a chemical reaction

• Products

• Reactants

• Starters

• Enders

Multiple Choice

The substances listed on the right side of a chemical equation are the

• Yields

• Reactants

• Products

• Precipitates

Multiple Choice

The process by which one or more substances change to produce one or more different substances

• Chemical Process

• Reactant

• Chemical Reaction

Multiple Choice

In the equation,          2Mg + O₂ ---> 2MgO, which are the reactants?

• Mg and O

• MgO

• Mg and MgO

• O and MgO

​Diatomic Elements

​ H₂ , N₂ , F₂ , O₂ , I₂ , Cl₂ , Br₂

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These only exist in nature as diatomic elements.

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These consist of Hydrogen, Nitrogen and the Halogens​

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When you breathe oxygen, you are breathing O₂

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Remember the pneumonic:​

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Assignment 1 - Writing a chemical equation from a word equation WS

REVIEW QUESTION TIME!

Multiple Choice

bond in which one or more electrons from one atom are removed and attached to another atom, resulting in positive and negative ions which attract each other

• Covalent Bond

• Ionic Bond

• Reaction Bond
• Null Bond

Multiple Choice

an atom or molecule which has gained or lost one or more of its valence electrons

• Covalent Bond

• Chemical Formula

• Ion

• Compound

Multiple Choice

a substance that is formed as the result of a chemical reaction

• Product 

• Reactant

• Starters

• Enders

Multiple Choice

the starting materials in a chemical reaction

• Products

• Reactants

• Starters

• Enders

Multiple Choice

Describes the number of atoms in a compound of each element. 

• coefficient 

• superscript 

• subscript 

• SI unit 

Multiple Choice

the symbolic representation of a chemical reaction

• Long Hand

• Short Hand

• Electron Configuration

• Chemical Equation

​Review Naming compounds

Multiple Choice

Which of these combinations is an ionic compound made of?

• Metal and Metal

• Nonmetal and Nonmetal

• Metal and Nonmetal

• Cation and Cation

Multiple Choice

LiBr is called

• lithium bromine

• lithium (I) bromine

• lithium bromide

• lithuim (I) bromide

Multiple Choice

The name of FeCl₂ is

• iron chloride

• iron (II) chloride

• iron (I) chloride

• iron dichloride

Multiple Choice

Name the following ionic compound: MgSO₄

• magnesium sulfoxide

• magnesium sulfide

• magnesium sulfate

• magnesium oxide

Multiple Choice

The formula of calcium phosphate is 

• CaPO₄

• Ca₂(PO₄)₃

• Ca₃PO₄

• Ca₃(PO₄)₂

Multiple Choice

How do the following two elements bond together?
Cr³⁺  O^2-         

• CrO

• Cr₃O₂

• Cr₂O₃

• CrO₃

Multiple Choice

How do the following two elements bond together?
K¹⁺  S^2- 

• KS

• K₈S

• K₆S₃

• K₂S

Multiple Choice

How do the following two elements bond together?
Al³⁺  O^2-         

• AlO

• Al₂O₃

• Al₃O₆

• Al₃O₂

Multiple Choice

Cu ⁺²  and  OH ^-

• CuOH₂

• Cu₂OH

• Cu(OH)₂

• correct answer is not given

Molecular prefixes

CO₂ is called carbon dioxide

N₂O₅ is called dinitrogen pentoxide

Multiple Choice

What is the name of N₂O?

• nitrogen oxide

• dinitrogen monoxide

• nitrogen monoxide

• dinitrogen oxide

Multiple Choice

Phosphorous trichloride

• PCl₃

• P₃Cl

• P₃Cl₃

• PCL

Multiple Choice

Disulfur trioxide

• S₃O₂

• SO

• S₂O₃

• S₂O

Multiple Choice

Carbon dioxide

• C₂O₂

• C₂0

• CO

• CO₂

Multiple Choice

What is the formula for hydrobromic acid acid?

• HBr

• HB

• HBrO₃

• HBO₃

Multiple Choice

What is the formula for nitrous acid?

• HNO₂

• H₃NO₂

• H₂NO₂

• HNO₃

Multiple Choice

carbonic acid

• H₂CO₃

• H₂CrO₄

• H₂C₂O₄

• HCO₃

Multiple Choice

What is the formula for nitric acid?

• HNO₃

• HNO₂

• HNO₄

• NO

​This law means that chemical equations must be balanced. They must have the same atoms on the the right side as on the left

​Law of Conservation of Matter

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"Matter is neither created nor destroyed"

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In a chemical reaction, atoms just rearrange. Did you hear that!!!!!​

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​Group Activity - Atoms just Rearrange!

REMEMBER

# of each element in reactants

MUST EQUAL

# of each element in products

2Al₂(CO₃)₃

• Al: 4 because 2 x 2 = 4

• C: 6 because 2 x 3 = 6

• O: 18 because 3 x 3 x 2 = 18

A few hints:

• Water can often be split into H + OH, but not always

• Save O for last in a reaction that produces CO2 + H₂O

• Polyatomics can be left as one thing if it appears on both sides of the yield

• Balance everything other than O and H first

• Try to get rid of odd numbers first

Practice Problems

Number your paper 1 - 7

___ H₂ + ___ O₂ → ___H₂O

Balance this equation.

___SiO₂ + ___C → ___Si + ___CO

Balance this equation.

__AgNO₃ + __MgCl₂

→

__AgCl + __Mg(NO₃)₂

Balance this equation.

___H₂SO₄ + ___NaOH -->

→

___Na₂SO₄ + ___H₂O

Balance this equation.

__C₃H₈ + __O₂ → __CO₂ + __H₂O

Balance this equation.

Multiple Choice

Which of the pictures below shows a balanced representation of

H₂ + O₂ → H₂O?

Assignment 2 - Writing and Balancing Chemical Eqns WS