This shortcut employs the coefficients from the balanced equation to create a volume ratio that converts directly from volume of one gas to volume of another. The following hypothetical case illustrates the underlying logic. Consider two gases, A and B, at the same temperature and pressure. The ratio of their volume to the moles of gas can be determined from the ideal gas equation.
Covalent bonds involve sharing of valence electrons. Very ionic crystals usually involve cations which are alkalis or alkaline-earths first two columns of the periodic table and oxygen or halogens as anions. The building criteria for the crystal structure are two: This leads to contact, configurations where anions have the highest number of cation neighbors and viceversa.
For example, in the NaCl structure Fig. Other structures were shown in class, but will not be included in the test. Their combination silicates occur in rocks, soils, clays and sand. The tetrahedron is charged: Silicates differ on how the tetrahedra are arranged.
In silica, SiO2every oxygen atom is shared by adjacent tetrahedra. Silica can be crystalline e. Soda glasses melt at lower temperature than amorphous SiO2 because the addition of Na2O soda breaks the tetrahedral network.
A lower melting point makes it easy to form glass to make, for instance, bottles. Diamond has very interesting and even unusual properties: Future applications of this latter, cheaper production method include hard coatings for metal tools, ultra-low friction coatings for space applications, and microelectronics.
Graphite has a layered structure with very strong hexagonal bonding within the planar layers using 3 of the 3 bonding electrons and weak, van der Waals bonding between layers using the fourth electron.
This leads to easy interplanar cleavage and applications as a lubricant and for writing pencils. Graphite is a good electrical conductor and chemically stable even at high temperatures.
Applications include furnaces, rocket nozzles, electrodes in batteries. A recently discovered formed of carbon is the C60 molecule, also known as fullerene or bucky-ball after the architect Buckminster Fuller who designed the geodesic structure that C60 resembles.
Fullerenes and related structures like bucky-onions amd nanotubes are exceptionally strong. Future applications are as a structural material and possibly in microelectronics, due to the unusual properties that result when fullerenes are doped with other atoms. Their formation is strongly affected by the condition of charge neutrality creation of unbalanced charges requires the expenditure of a large amount of energy.
Non-stoichiometry refers to a change in composition so that the elements in the ceramic are not in the proportion appropriate for the compound condition known as stoichiometry. To minimize energy, the effect of non-stoichiometry is a redistribution of the atomic charges Fig.
Charge neutral defects include the Frenkel and Schottky defects. A Frenkel-defect is a vacancy- interstitial pair of cations placing large anions in an interstitial position requires a lot of energy in lattice distortion.
A Schottky-defect is the a pair of nearby cation and anion vacancies. Introduction of impurity atoms in the lattice is likely in conditions where the charge is maintained. This is the case of electronegative impurities that substitute a lattice anions or electropositive substitutional impurities. This is more likely for similar ionic radii since this minimizes the energy required for lattice distortion.
Defects will appear if the charge of the impurities is not balanced. It occurs due to the unavoidable presence of microscopic flaws micro-cracks, internal pores, and atmospheric contaminants that result during cooling from the melt.
The flaws need to crack formation, and crack propagation perpendicular to the applied stress is usually transgranular, along cleavage planes.
The flaws cannot be closely controlled in manufacturing; this leads to a large variability scatter in the fracture strength of ceramic materials. The compressive strength is typically ten times the tensile strength. This makes ceramics good structural materials under compression e.
Plastic deformation in crystalline ceramics is by slip, which is difficult due to the structure and the strong local electrostatic potentials.Honors Chemistry. Chapter 3 Study Questions. 1. Glycerol (C3H8O3) is sold in drug stores as glycerine and is commonly found in soaps and shampoos.
1 Chapter 3 Centrifugation Biochemistry and Molecular Biology (BMB) Introduction Basic Principle of sedimentation Types, care and safety of centrifuges. Introduction. Ceramics are inorganic and non-metallic materials that are commonly electrical and thermal insulators, brittle and composed of more than one element (e.g., two in Al 2 O 3.
Chapter Chemical Equilibrium Key topics: Equilibrium Constant Calculating Equilibrium Concentrations The Concept of Equilibrium Consider the reaction.
Many valuable technologies operate in the radio (3 kHz GHz) frequency region of the electromagnetic spectrum. At the low frequency (low energy, long wavelength) end of this region are AM (amplitude modulation) radio signals ( kHz) that can travel long distances. Learning Objectives. By the end of this section, you will be able to: Describe the Bohr model of the hydrogen atom; Use the Rydberg equation to calculate energies of light emitted or .