Delta
What does thermochemistry study?
Heat changes in chemical and physical processes
Temperature is a measure of:
The average kinetic energy of particles
When you hold a mug of hot cocoa, your hands feel warm because:
Heat flows from the mug to your hands
A positive ΔH value indicates that a reaction is:
Endothermic
What is the definition of an exothermic reaction?
A reaction that releases heat
What unit is commonly used to measure heat energy?
Joule
In a potential energy diagram for an exothermic reaction, the products have:
Less energy than the reactants
When baking bread in an oven, the bread acts as the system. Is the baking process endothermic or exothermic?
Endothermic, because the bread absorbs heat
In thermochemistry, what do we call the specific part of the universe we are studying?
The system
If a chemical cold pack feels cold to the touch, what kind of reaction is happening inside?
Endothermic
What is the minimum energy required to start a chemical reaction called?
Activation energy
What happens to particle motion when heat is added to a solid?
The particles move faster
Heat always flows from:
Warmer objects to cooler objects
Which of the following phase changes releases energy (exothermic)?
Condensation (gas to liquid)
Evaporation of sweat cools the body because it is an:
Endothermic process that absorbs heat from the skin
Which scenario represents an exothermic reaction?
Lighting a match
What happens to the temperature of the surroundings during an exothermic reaction?
it increases
The law of conservation of energy states that:
Energy cannot be created or destroyed
Which symbol represents the change in enthalpy (heat content) of a system?
ΔH
Which of the following is an endothermic process?
a) Melting ice
b) Burning wood
c) Freezing water
d) A firework exploding
A) Melting Ice