Honors Chemistry: Matter Quizlet
Lessons 1.3 & 1.4 — Properties of Matter and Changes in Matter
Lesson 1.3: Properties of Matter
A property of a substance that can be observed or measured without changing the substance’s composition. You can identify matter the same way you recognize a friend — by appearance and measurable traits.
A physical property that depends on the amount of matter in a sample.
Examples: mass, volume, length.
A physical property that depends on the type of matter in a sample, not the amount. The identity of the substance stays the same no matter how much you have (for example, 1 L of water and 1000 L of water both freeze at 0 °C).
Examples: melting point, boiling point, density, temperature, conductivity, solubility, state of matter, specific heat.
An intensive physical property that can be used to identify a substance because it does not change with sample size.
Examples: density, melting point, boiling point, and specific heat.
The ability of a substance to undergo a change that alters its chemical composition. These describe how a substance behaves when it reacts.
A measure of how easily a substance will be set on fire.
The ability to burn in the presence of oxygen. Describes how easily a substance burns.
Chemical combination with oxygen.
Example: rust forming on iron.
Breakdown or degradation of a metal due to a reaction with the environment.
To dull the luster, or discolor, especially by exposure to air and dirt.
How readily a substance reacts with acids, water, or other substances. A chemical property used to describe a material’s tendency to undergo chemical change.
Lesson 1.4: Changes in Matter
A change that involves changing physical properties without changing the composition of the material. Many physical changes are reversible.
Examples: phase changes and dissolving.
The most common type of physical change. Matter changes from one state (solid, liquid, or gas) to another, but the chemical identity stays the same.
Phase change from a solid (s) to a liquid (l). Heat is absorbed, so this is endothermic.
Example: H2O(s) + heat → H2O(l)
Phase change from a liquid (l) to a gas (g) at its boiling point. Endothermic.
Example: H2O(l) + heat → H2O(g)
Phase change from a liquid (l) to a gas (g) at any temperature, from the surface of the liquid. Endothermic. Unlike vaporization, it does not require the boiling point.
Phase change from a gas (g) to a liquid (l). Heat is released, so this is exothermic. Condensation is the reverse of vaporization.
Example: H2O(g) → H2O(l) + heat
Phase change from a solid (s) to a gas (g) without a liquid phase. Endothermic.
Examples: CO2(s) + heat → CO2(g) · I2(s) + heat → I2(g)
Phase change from a gas (g) to a solid (s) without a liquid phase. Heat is released (exothermic). Deposition is the reverse of sublimation.
A change that absorbs heat. Heat is written on the reactant (left) side of the equation.
Melting, vaporization, evaporation, and sublimation are endothermic.
A change that releases heat. Heat is written on the product (right) side of the equation.
Condensation and deposition are exothermic.
A physical combination of a solute in water to form an aqueous solution. The solute’s chemical identity does not change.
Example: NaCl(s) + H2O(l) → NaCl(aq)
A homogeneous mixture in which a pure substance is physically combined with (dissolved in) water. The symbol (aq) after a formula means the substance is dissolved in water.
A change that involves one or more substances being transformed into different substances with different properties. Often irreversible, or reversible only with an additional chemical change.
Evidence that a new substance may have formed:
- Production of heat or light
- Production of a gas
- Formation of a precipitate
- Color change
- Change in a distinct physical or chemical property
- Change in volume
- Change in melting point or boiling point
- Change in smell or taste
A common sign of a chemical change.
Example: Mg(s) + O2(g) → 2 MgO(s)
A sign of a chemical change when a gas is produced that was not already present as a phase change.
Example: Zn(s) + 2 HCl(aq) → ZnCl2(aq) + H2(g) + 415 kJ
A solid that forms when two aqueous solutions react. The new solid is evidence of a chemical change.
Example: Pb(NO3)2(aq) + 2 KI(aq) → PbI2(s) + 2 KNO3(aq)
An insoluble solid that forms during a chemical reaction in solution. Written with the symbol (s) as a product of two aqueous reactants.
Matter can neither be created nor destroyed in an ordinary physical or chemical change. The total mass of reactants equals the total mass of products.
Physical and chemical changes are accompanied by changes in energy. Energy may be released or absorbed, but energy cannot be created or destroyed in ordinary physical and chemical changes (1st Law of Thermodynamics).
Types of energy: chemical potential (bond) energy, thermal, electrical, nuclear, mechanical, light.