Topic 8 – Reaction Rate

Science 9 - Chemistry

Learning Target

1. Describe combustion, corrosion and other reactions involving oxygen

Chemical Reactions involving oxygen

1. COMBUSTION - oxygen reacts with a fuel source to produce water vapor, carbon dioxide gas and heat energy

Ex. Fire, explosion

What products are produced in combustion?

CH4(g) + 2 O2(g) CO2(g)+ 2 H2O (g)

Methane + oxygen carbon dioxide + water

2. CORROSION – slow chemical change when oxygen in air reacts with metalEx. Rust

4 Fe(s) + 3 O2(g) 2 Fe2O3(s)Iron + oxygen iron oxide

How do we protect against rust?

Galvanizing – Coating metals with thin layers of zinc– Zinc takes longer to rust than most metals!

Painting Sacrificial metal

PBS Nova – Smart Bridges

https://www.youtube.com/watch?v=8qcREJ2NsOQ (SmartBridge) https://www.youtube.com/watch?v=yVQn1D

YmiXE (War on Corrosion)

3. CELLULAR RESPIRATION – chemical reaction that takes place in your body cells.C6H12O6 + O2 CO2 + H2O + energy

Learning Target

Identify conditions that affect the rates of reactions.

Factors Affecting Rates of Chemical Reactions

REACTION RATE – the speed at which reactants are converted to products during a chemical reaction.

Factors Affecting Rates of Chemical Reactions

Many factors can affect chemical reactions– How can you make water boil faster?

1. Changing Temperature • Temp = reaction rate • Temp = reaction rate

2. Stirring the Reactants Adding movement energy and speed of

atoms / molecules = collisions between atoms = reaction rate

3. Increasing Surface Area surface area = reaction rate

Catalysts4. Catalysts – A substance that RR without being changed itselfEx. Enzyme (natural catalyst) – made by living things

Enzymes in the human body https://www.youtube.com/watch?v=myORDWVzNhc

5. Changing Concentrations – number of particles (atoms or molecules) per unit of volume changes reaction rate

# of particles / unit of volume = RR# of particles / unit of volume = RR

X mol/L acetic acid (aq)vs.

.8 mol/L acetic acid (aq)

Bozeman science https://www.youtube.com/watch?v=6mAqX31RRJU Ted-Ed

https://www.youtube.com/watch?v=OttRV5ykP7A