Unit 1 Review Pre-AP Chemistry: Structure & Properties of Matter

Flashcards cover key concepts from the lecture notes: unit conversions, calorimetry and specific heat calculations, phase changes, properties of states of matter, thermochemistry definitions, and basic gas theory.

A cookie contains 45 nutritional Calories. Convert this amount to small calories (cal) and to joules.

45 Cal = 45,000 cal; in joules: 45,000 cal × 4.184 J/cal = 188,280 J.

How many joules are absorbed when 100 g of water is heated from 10°C to the boiling point (c = 4.184 J/g°C)?

q = m c ΔT = 100 g × 4.184 J/g°C × (100 - 10)°C = 37,656 J.

Heat absorbed by 15.0 g of aluminum heated from 20°C to 350°C with c = 0.897 J/g°C.

ΔT = 330°C; q = m c ΔT = 15.0 g × 0.897 J/g°C × 330°C ≈ 4,440 J.

A 28 g coin absorbs 658 J while its temperature rises from 25°C to 125°C. What is the specific heat of the metal?

c = q /(m ΔT) = 658 J / (28 g × 100°C) ≈ 0.235 J/g°C.

A piece of erbium metal is cooled from 95.0°C to 50°C and releases 189 J of heat. If c = 0.1681 J/g°C, what is the mass?

q = m c ΔT; ΔT = 95.0 - 50.0 = 45.0°C; m = q /(c ΔT) = 189 J / (0.1681 J/g°C × 45°C) ≈ 25.0 g.

What are the freezing point and boiling point of water (at 1 atm) in °C?

Freezing point: 0°C; Boiling point: 100°C.

How does sublimation differ from deposition?

Sublimation is solid to gas; deposition is gas to solid.

What is the temperature at which a solid becomes a liquid called?

Melting point.

A liquid can change to a gas by vaporization. If vaporization occurs at the surface only, what is this specific process called?

Evaporation.

What is the name of the process by which a gas becomes a liquid?

Condensation.

H2O(g) → H2O(s) describes which phase change?

Deposition.

A sample with mass 75.0 g and volume 25.0 mL has what density (show work)?

Density = mass/volume = 75.0 g / 25.0 mL = 3.00 g/mL.

List the shape characteristics of solids, liquids, and gases.

Solids: definite shape; Liquids: indefinite shape; Gases: indefinite shape.

List the volume characteristics of solids, liquids, and gases.

Solids: definite volume; Liquids: definite volume; Gases: indefinite volume.

List the density characteristic of solids, liquids, and gases.

Solids: high density; Liquids: intermediate density; Gases: low density.

List the kinetic energy (KE) characteristics of solids, liquids, and gases.

Solids: low KE; Liquids: medium KE; Gases: high KE.

Are solids, liquids, and gases compressible? Specify which are compressible.

Solids and liquids are largely incompressible; gases are compressible.

Order the states of matter from lowest to highest KE.

Solid → Liquid → Gas.

Define heat in thermochemistry terms.

Heat is energy that flows due to a temperature difference.

Define temperature in terms of molecular motion.

A measure of the average kinetic energy of the particles in a sample.

Define specific heat.

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

What is a calorimeter used for?

A device used to measure the heat absorbed or released during a chemical reaction or physical process.

What is thermochemistry?

The study of energy changes, particularly heat, during chemical reactions.

State the formula used to calculate heat gained or lost and what each symbol represents.

Q = cmΔT where Q is heat, c is specific heat, m is mass, and ΔT is change in temperature.

What is the difference between heat of fusion and heat of vaporization, and which is smaller for the same substance?

Heat of fusion is the energy to melt a solid; heat of vaporization is to vaporize a liquid. For the same substance, heat of fusion is smaller.

Describe the energy changes when cooling a gas to a liquid and then to a solid, naming the phase changes.

Gas to liquid: condensation releases latent heat; liquid to solid: freezing releases latent heat.

What are the four variables used to describe gases?

Pressure, Volume, Temperature, and Amount (moles).