Unit 13 chem test

What is energy?

The ability to do work.

What is kinetic energy?

Energy of motion.

What is potential energy?

Energy of position or composition.

State the Law of Conservation of Energy.

Energy is neither created nor destroyed; the total energy of the universe is constant.

What is thermodynamics?

The study of energy changes during chemical reactions, temperature changes, and phase changes.

What is heat (q)?

Energy transferred because of a temperature difference.

Which direction does heat flow spontaneously?

From warmer objects to cooler objects.

What is the SI unit of energy?

Joule (J).

How many joules are in 1 kilojoule?

1000 J.

What is a system?

The part of the universe being examined.

What are surroundings?

Everything outside the system.

What is an endothermic process?

A process where the system absorbs heat from the surroundings.

What is an exothermic process?

A process where the system releases heat into the surroundings.

Give two examples of endothermic processes.

Melting, evaporating/boiling.

Give two examples of exothermic processes.

Freezing, condensing.

What is specific heat capacity?

The heat needed to raise the temperature of 1 gram of a substance by 1°C.

What does a high specific heat indicate about a substance?

It is difficult to change its temperature; good insulator.

What is the specific heat of liquid water?

4.18 J/(g·°C).

Write the formula for calculating heat during a temperature change.

q = m × c × ΔT.

In q = m × c × ΔT, what does each variable stand for?

q = heat (J), m = mass (g), c = specific heat (J/g°C), ΔT = change in temperature (°C or K).

How do you calculate ΔT?

ΔT = T_final - T_initial.

What is calorimetry?

The process that measures heat exchanged.

What is a calorimeter?

An insulated device that measures heat absorbed or released.

What is heat of fusion?

Energy required to change a solid at its melting point to a liquid.

What is heat of vaporization?

Energy required to change a liquid at its boiling point to a gas.

Write the formula for heat absorbed during melting.

q = m × ΔH_fusion.

Write the formula for heat released during freezing.

q = m × (-ΔH_fusion).

Write the formula for heat absorbed during evaporation.

q = m × ΔH_vaporization.

Write the formula for heat released during condensation.

q = m × (-ΔH_vaporization).

What is activation energy?

The energy required for a reaction to proceed.

What is the activated complex (transition state)?

The highest energy point between reactants and products on an energy diagram.

In an endothermic reaction diagram, are products higher or lower in energy than reactants?

Higher.

In an exothermic reaction diagram, are products higher or lower in energy than reactants?

Lower.