Intro to matter
What is the difference between chemical and physical properties?
A physical property is a characteristic that can be observed without changing the chemical make-up of the substance and chemical property is how a substance reacts in the presence of another substance, and it cannot be observed without changing the chemical composition.
They are composed of molecules of two identical atoms covalent bonded together.
What are diatomic molecules?
How is temperature and kinetic energy related?
The particles of all substances at the same temperature have the same average kinetic energy. The higher the temperature the greater the average kinetic energy of the particles and the faster they move.
What transfers heat energy?
Thermal energy
When heating water in an aluminum pan, the metal pan gets hotter than the water. Explain this observation in terms of specific heat capacity.
Water has a higher specific heat capacity than aluminum, meaning it requires more energy to increase its temperature. Therefore, when both are heated equally, the aluminum pan reaches a higher temperature.
Identify all states of matter and their structure and arrangement of the particles.
(100 points bonus if you identify the attractions between the particles)
Solid state, particles are packed closely together in a regular, repeating, 3D pattern called a crystal lattice.
Liquid state, particles are close together but have no regular arrangement.
Gas state, particles are arranged randomly and very far apart.
(Bonus: Solid state has strong attractions that hold the particles in fixed positions, while liquid state has attractions between particles that are strong enough to hold the particles close so the sample has definite volume, but not strong enough to keep the particles packed in fixed positions, and gas state has no forces of attraction between particles.)
A process used to separate the components of a mixture based on difference in solubility.
What is filtration?
Explain, in terms of energy, why warm water evaporates faster than cold water?
Warm water evaporates faster than cold water because the water molecules in warm water possess more kinetic energy. This higher kinetic energy allows a greater proportion of molecules to overcome the intermolecular forces holding them in the liquid phase and transition into the gaseous phase (evaporation). In contrast, the molecules in cold water have less kinetic energy, meaning fewer can escape into the air as vapor.
Classify the following physical changes as exothermic or endothermic:
(a) melting wax
(b) condensation on a car window
(c) freezing popsicles
(d) sublimation of snow
(e) evaporation of sweat from your skin
(a) endothermic
(b) exothermic
(c) exothermic
(d) endothermic
(e) endothermic
What is heat of fusion and heat of vaporization?
“Heat of fusion" refers to the amount of energy needed to change a solid substance into a liquid (melting), while "heat of vaporization" is the amount of energy required to transform a liquid into a gas (boiling).
Describe physical and chemical changes
Physical change is the change in the appearance of a sample and chemical change (also known as chemical reaction) results in the formation of different substances having different chemical and physical properties.
What is chromatography?
A process used to separate the components of a mixture based on the difference in molecular polarity.
List all forms of energy (9)
(200 bonus define all of them)
Kinetic energy (KE): energy of motion where all particles of matter are in constant motion.
Potential energy (PE): stored energy or energy of position.
Chemical energy: the energy associated with the breaking and forming of chemical bonds, is a form of potential energy.
Electrical energy: energy produced by the movement of electrical charges.
Thermal energy: energy associated with the random motion of atoms and molecules.
Radiant (Light) energy: energy transferred as an electromagnetic wave.
Mechanical energy: energy associated with a force causing an object to move or charge its existing motion.
Heat energy: energy transferred from a sample at a higher temperature to a sample at a lower temperature.
What is the significance of absolute zero? What temperature is absolute zero on the kelvin and Celsius scales?
0 K and -273.15 °C
Absolute zero is the lowest possible temperature where all molecular motion ceases. On the Kelvin scale, absolute zero is 0 K, and on the Celsius scale, it is -273.15 °C.
In a calorimeter, 40 grams of water surrounds a sealed reaction chamber. How many joules of heat energy are realized by the reaction if the temperature of the water changes from 20 degrees C to 45 degrees C?
4180J
in all chemical and physical changes, matter is neither created nor destroyed; it is only changed in form.
What is the law of conservation of matter?
Describe the process of distillation.
In distillation a mixture is heated until one of the components reaches its boiling point and vaporizes; the vapors rise up from the mixture and condense back into a liquid in a separate container.
Given the following sample of matter:
(1) 10 ml H2O(l) at 50 degrees Celsius
(2) 50 ml H2O(l) at 25 degrees Celsius
(3) 25 ml H2O(l) at 50 degrees Celsius
(4) 50 ml H2O(l) at 100 degrees Celsius
Fill in the blanks:
___ (a) which sample contains particles with the highest average kinetic energy?
___ (b) which sample contains particles with the lowest average speed?
__&__ (c) which samples contain particles with the same average kinetic energy?
(a) 4
(b) 2
(c) 1 & 3
Explain endothermic and exothermic changes and where they go in a reactant and protect equation
A change in matter can be an exothermic change in which energy is released to the surrounding environment or an endothermic change, in which energy is absorbed from the surrounding environment.
In exothermic the heat energy goes on the product side, where it is released, and on the reactant side in endothermic where heat energy is absorbed.
Draw a heating and cooling curve and label the lines with:
Gas, liquid, solid, melting, condensation, boiling, and freezing.
Compare to figures 6-6. And 6-7. In chem book.
List all classification of matter (6) and what each of them do and how they are related.
Mixture — l — Pure substance
1. Heterogeneous 1. Element
2. Homogeneous 2. Compound
A mixture can be composed of two or more substances that are physically combined but not chemically bonded together. It can be a homogeneous mixture, also called a solution, that is uniform in composition through the sample, or a heterogeneous mixture that is not uniform in composition and properties throughout the sample.A pure substance is any variety of matter that has a constant composition and properties throughout a given sample and from sample to sample. It could be an element which cannot be broken down into simpler substances by physical or chemical change. Or a compound which is composed Of two or more elements chemically bonded together in a definite proportion.
Directions: answer both questions right and explain why!! (or no points)
1. which has the highest entropy?
(1) NH3(s)
(2) NH3(l)
(3) NH3(g)
(4) NH3(aq)
2. A bottle of rubbing alcohol contains both 2-propanol and water. These liquids can be separated but the process of distillation because 2-propanol and water…
(1) have combined chemically and retain their different boiling points
(2) have combined chemically and have the same boiling points
(3) have combined physically and retain their different boiling points
(4) have combined physically and have the same boiling points
1. (3) bc Entropy is a measure of the disorder or randomness of a system. Gases have higher entropy than liquids, which have higher entropy than solids. Aqueous solutions (aq) have intermediate entropy.
2. (3) bc Distillation is not effective if two substances have the same boiling point or chemically combine, as 2-propanol and water are separated by distillation due to physical combination.
Explain the phase changes of endothermic and exothermic step by step using the words:
Fusion, vaporization, solidification, condensation, sublimation, endothermic, solid, liquid and gas.
The phase transitions between solid, liquid, and gas states of matter. Endothermic processes (heat absorbed) include fusion (melting), vaporization (boiling), and sublimation (solid to gas). Exothermic processes (heat released) include solidification (freezing), condensation (gas to liquid), and deposition (gas to solid).
Balance and write where the heat energy is of these equations:
1. Respiration : _C6H12O6 + _O2 (+____ ) -> _CO2 + _H2O (+_____ )
2. Photosynthesis : _CO2 + _H2O (+_____ ) -> _C6H12O6 + _O2 (+____ )
1. Respiration : C6H12O6 + 6O2 -> 6CO2 + 6H2O + energy
2. Photosynthesis : 6CO2 + 6H2O + energy -> C6H12O6 + 6O2
A piece of gold (Cp= 1.129 J/g degrees C) with a mass of 20 grams and a temperature of 50 degrees C is dropped into 192 grams of water at 10 degrees C, what is the final temperature of the system?
11.09 degrees C