Reaction Rates
Chemistry is Everywhere
Get out your Calculators!
Under Pressure
Chemmon Sense
100
The rate of a reaction is the amount of a ______ that is consumed or a ______ that is produced per unit time.
reactant, product
100
Why does food last longer in the fridge than on the counter?
Lower temperature slows chemical reactions that cause spoilage, bacteria grows slower, particles move slower (fewer collisions).
100
Convert 2 days into minutes.
2 880 minutes.
100
What happens to gas pressure when volume decreases and temperature stays constant?
Pressure increases.
100
Why does ice float in water?
Solid water is less dense than liquid water.
200
A reaction stops even though reactants are still present. What could explain this?
- Temperature dropped
- A catalyst was removed
- Reactants were no longer colliding effectively
- All products were removed
200
You crush a sugar cube before adding it to your coffee - compared to the whole cube, will the reaction rate be faster, slower, or the same?
Faster, more surface area.
200
A 15.0g piece of hot metal at 150.0 is placed in 100.0g of water at 20.0°C. The final temperature of the water is 25.0°C. What is the heat absorbed by the water?
2 090J or 2.09kJ
200
A gas is at 2.0 L and is compressed to 1.0 L (temp constant).
Pressure becomes ___ times bigger.
2
200
Why does increasing concentration increase the rate of a reaction?
More particles per volume → more collisions.
300
A catalyst is added to a reaction. On a Maxwell–Boltzmann (Energy Distribution) graph, what changes?
The activation energy (Ea) is lowered.
300
How do antacid medications (like pepcid) help relieve heartburn?
They neutralize excess stomach acid (acid–base neutralization).
300
A student burns 22.0 g of propane (C₃H₈).
How many moles of propane are burned?
0.50mol
300
Which law describes the relationship between pressure and volume?
Boyle's Law
300
During your Water Flow lab, name 1 possible source of experimental error.
- reading a moving value
- human reaction time
400
Rate the following reaction as fast or slow (@ room temperature) and justify your answer:
2KOH(aq) + H2SO4(aq) → 2H2O(l) + K2SO4(aq)
Fast, ionic bond changes (i.e. neutralization) happen quickly.
400
Explain how the chemical properties of acids make metal containers unsuitable for storing acidic foods (like lemon juice).
Acids react with metals
Corrosion occurs
Metal can dissolve into food
400
A reaction uses up 0.40 mol of reactant in 5.0 minutes.
Calculate the average rate of reaction in mol/s.
0.0013 × 10 mol/s
400
A gas has a volume of 4.0 L at 100 kPa. If the pressure increases to 200 kPa, what is the new volume (if temperature remains constant)?
2.0L
400
Label A, B, D, and E, and state if the graph is illustrating an endothermic or exothermic reaction.
A = Energy of reactants
B = Activation energy (Ea)
D = Energy of products
E = ΔH (heat of reaction, enthalpy)
Exothermic
500
For a reaction: Rate = k[A]²[B]
If [A] is doubled and [B] stays constant, the rate changes by what factor?
The rate increases by a factor of 4.
500
Write an equation for the complete combustion of propane in your BBQ (C3H8).
Bonus: Balance the equation.
C3H8 + 5O2 → 3CO2 + 4H2O
500
A 7.00g sample of methane gas (CH4) was burned in oxygen. After 1 minute and 49 seconds, 2.00g of methane remained.
Calculate the average rate of combustion of methane gas in mol/s.
0.00285 mol/s
500
A balloon filled with air is placed in a freezer and then taken out after a few minutes. Name 1 effect you would observe and explain why.
Balloon shrinks - particles move slower
500
A metal spoon and a wooden spoon are left in a pot of hot soup for a few minutes. You notice that the metal spoon feels much hotter - why?
- Metal is a better thermal conductor
- Heat transfers faster through metal than wood