TYPES OF REACTIONS
Is grinding coffee beans a physical or chemical change?
Physical change
Which gas law explains gas expansion when coffee is heated?
Charles’s Law
What is the chemical formula of caffeine?
C₈H₁₀N₄O₂
What is a limiting reactant?
The reactant that runs out first
How many particles are in one mole?
6.022 × 10²³
What type of reaction breaks caffeine down in the liver?
Metabolic (biochemical) reaction
What happens to gas volume when temperature increases?
Volume increases
Why are element ratios in caffeine always the same?
Chemical formulas have fixed ratios
What happens when the limiting reactant is used up?
The reaction stops
What is the molar mass of caffeine?
194.22 g/mol
Why is heating coffee not a chemical reaction involving caffeine?
Only temperature changes; caffeine’s chemical structure stays the same
Why does hot coffee smell stronger than cold coffee?
Expanding gases carry aroma molecules
How many carbon atoms are in one caffeine molecule?
8
In caffeine synthesis, what does the limiting reactant control?
How much caffeine is formed
What does molar mass connect?
Mass and number of moles
Name one chemical change involving caffeine.
Caffeine metabolism / oxidation by enzymes
Is gas expansion in coffee a physical or chemical change?
Physical change
What does stoichiometry help chemists calculate for caffeine?
Amounts of substances in reactions
If methyl groups run out first, what happens?
Less caffeine is produced
Why do chemists use moles instead of counting molecules?
Molecules are too small to count individually
Why is caffeine metabolism NOT a decomposition reaction?
It occurs through multiple enzyme-catalyzed reactions, not a single breakdown
What would happen to pressure if gas from hot coffee were trapped?
Pressure would increase
Why is stoichiometry important in caffeine synthesis?
It determines how much caffeine can be produced
Why do both plants and labs depend on limiting reactants?
They determine caffeine yield
Drinking coffee introduces about how many caffeine molecules into the body?
Around 10²⁰–10²¹ molecules