Unit 6 Section 2: Types of Chemical Reactions

Unit 6 Section 2: Determination of Chemical Reactions

Multiple Choice

What term represents with symbols and formulas the identities and relative molecular or molar amounts of the reactions and products in a chemical reaction?

• A chemical Equation

• A Reaction Write up

• A Balancing exercise

• Equation Symbols

Multiple Choice

Is this equation balanced?

• Yes

• No

Multiple Select

Which of the following indicates that a chemical reaction has taken place?

• Release of energy as heat

• Release of energy of light

• Production of Gas

• Formation of a Precipitate

Multiple Choice

How many oxygens are in Al₂(SO₄)₃?

• 4
• 12
• 7
• 24

Multiple Choice

Is the equation balanced?: 2H₂O + O₂ --> 4MgO + 3Fe

• Yes
• No

Drag and Drop

Balance this equation
​

Placeholder

N₂ + ​

Placeholder

H₂ --> ​

Placeholder

NH₃

Drag these tiles and drop them in the correct blank above

5

6

4

1

3

2

7

8

9

Lesson Objectives

• Distinguish between endothermic and exothermic reactions

• Explain what causes chemical reactions

• Identify the five general types of chemical reactions and describe the components in these reactions

  • Predict the outcome of certain reactions based on these components

Significance of a chemical equation

• A chemical equation can be used to solve for quantities

• Information Revealed

  • The coefficients indicate the relative amounts of reactants and products

    • Coefficients tell you the number of moles involved

    • Multiplying all the coefficients by the same value allows us to scale up a reaction

  • We can determine the Minimum relative masses of the reactants and products in an equation​

Energy of Reactions

• Recall: All bonds are held together by stored potential energy

• During reactions, bonds are broken and formed

  • energy is needed to break bonds and is released when bonds are formed

• Law of Conservation of Energy: In any chemical reaction, energy is neither created nor destroyed

  • Any excess energy is absorbed by the surroundings

Endothermic and Exothermic

• All reactions either absorb or release energy.

• Exothermic: Reactions that Release energy to the surroundings

  • Products store less energy than reactants

• Endothermic: Reactions that absorb energy from the surroundings

  • Products store more energy than reactants

What causes reactions?

• Collision theory: Reactions only occur when reactants collide with enough energy at the right angle

• Reaction rate: the speed at which reactants become products

  • As reactants move faster, more collisions occur, making the reaction occur faster

    • Higher temperature=more movement=faster reaction rate

Drag and Drop

An ​

Placeholder

the reaction releases energy into the surroundings and has lower energy in products than in the reactants

Drag these tiles and drop them in the correct blank above

exothermic

endothermic

catalytical

synthesis

Drag and Drop

The Law of conservation of ​

Placeholder

says that energy in a reaction is neither created nor destroyed.​

Drag these tiles and drop them in the correct blank above

energy

matter

time

charge

temperature

Multiple Choice

What does collision theory state?

• Chemical reactions occur without any collision
• Reactant molecules collide with low kinetic energy
• Chemical reactions can occur only when reactant molecules collide with enough kinetic energy at the right angle

• Kinetic energy has no effect on chemical reactions
• Chemical reactions can occur only when reactant molecules collide with enough kinetic energy at any angle

Multiple Choice

How does temperature relate to reaction rate?

• Temperature has no effect on reaction rate.
• As temperature increases, the reaction rate generally decreases.
• As temperature decreases, the reaction rate generally increases.
• As temperature increases, the reaction rate generally increases.

Types of Chemical Reactions

• We classify reactions into different types based on what happens in them

  • The types we will discuss in this class

    • Synthesis

    • Decomposition

    • Single Displacement

    • Double Displacement

    • Combustion​

Synthesis Reactions

• In a Synthesis reaction, two or more substances combine to form a new compound

  • Represented by the following general equation: A + X --> AX

• Reactions of elements with Oxygen

  • One simple type of synthesis is the combination of an element with oxygen to form an oxide​

    • Almost all metals react to form oxides​

  • Most metals react with the halogens (group 17) to form compounds​

Decomposition Reactions

• In Decomposition Reactions, a single compound undergoes a reaction that produces two or more simpler substances

  • Shown by the general equation AX --> A + X​

  • Most only take place when energy is added to the system

    • Electrolysis: the decomposition of a substance by an electric current​​

Single Displacement

• In a Single Displacement reaction, one element replaces a similar element in a compound

  • Shown by the general equation A + BX --> AX+B

• ​Displacement of a metal by another metal: One metal replaces another

• Displacement of hydrogen in water by a metal

  • Water forms a hydroxide with a metal

• Displacement of hydrogen in an acid by a metal

  • Metals replace the hydrogen in the acid

• Displacement of halogens

Single Displacement-Activity Series

• Activity Series: a list of elements organized according to the ease with which the elements undergo certain chemical reactions

  • tells how likely an element is to take part in a reaction

    • Metals lose electrons at higher activity levels

    • non-metals gain electrons

  • Elements can replace any element underneath them on the list, but not any element above them​

    • Halogens are special, they are in the exact order they are in on the Periodic table

Multiple Choice

Based on the activity series will the following reaction take place:

$$Zn_{\left(s\right)}+H_2O_{\left(l\right)}\ \frac{50\degree C}{\rightarrow}$$  

• Yes

• No

• Zinc only reacts with water when it is in Steam. Water boils at 100 Degrees Celsius, so this reaction will not take place

Multiple Choice

Based on the activity series will the following reaction take place?

$$Sn_{\left(s\right)}\ +O_{2\left(g\right)}\rightarrow$$  

• Yes

• No

Multiple Choice

Based on the activity series will the following reaction take place?

$$Cd_{\left(s\right)}+Pb\left(NO_3\right)_{2\left(aq\right)}\rightarrow$$  

• Yes

• No

Multiple Choice

Based on the activity series will the following reaction take place?

$$Cu_{\left(s\right)}+HCl_{\left(aq\right)}\rightarrow$$  

• Yes

• No

Multiple Choice

Based on the activity series will the following reaction take place?

$$MgCl_{2\left(aq\right)}+Zn_{\left(s\right)}\rightarrow$$  

• Yes

• No

Double Displacement Reactions

• In a Double Displacement reaction the ions of two compounds exchange places in an aqueous solution to form two new compounds

  • Represented by the equation: AX + BY --> AY + BX​

  • ​Leads to the formation of a Precipitate

  • In some double displacement reactions, one of the products is a gas

    • Some result in liquid water as well​

Combustion Reactions

• In a Combustion reaction, a substance combines with Oxygen, releasing a large amount of energy in the form of light and heat

  • The reactants tend to be hydrocarbons, Chemicals only containing Carbon and Hydrogen​

  • Products are usually Carbon Dioxide and Water, but carbon monoxide may also be a product

• Combustion reactions are often used to generate energy​

Multiple Choice

This type of reaction results in two or more reactants making one new substance

• Synthesis

• Decomposition

• Single Displacement

• Double Displacement

• Combustion

Multiple Choice

This type of reaction results in two Compounds switching or "trading" one of their ions.

• Synthesis

• Decomposition

• Single Displacement

• Double Displacement

• Combustion

Multiple Choice

Which metal is more reactive than calcium?

• magnesium

• potassium

• silver

• aluminum

Multiple Choice

This type of reaction results in one reactant undergoing a change that results in two or more products

• Synthesis

• Decomposition

• Single Displacement

• Double Displacement

• Combustion

Multiple Choice

This type of reaction results in one reactant replacing an ion on one of the other reactants

• Synthesis

• Decomposition

• Single Displacement

• Double Displacement

• Combustion

Multiple Choice

Will silver react with magnesium chloride solution?

• yes

• no

Multiple Choice

This type of reaction results in Heat, light, carbon dioxide and water as products

• Synthesis

• Decomposition

• Single Displacement

• Double Displacement

• Combustion