AS/A Level Chemistry (A) specimen question papers and mark
... Write your name, Centre number and candidate number in the spaces provided on the answer booklet. Write all your answers on the separate answer paper provided. If you use more than one sheet of paper, fasten the sheets together. Answer all questions. INFORMATION FOR CANDIDATES The number of marks is ...
... Write your name, Centre number and candidate number in the spaces provided on the answer booklet. Write all your answers on the separate answer paper provided. If you use more than one sheet of paper, fasten the sheets together. Answer all questions. INFORMATION FOR CANDIDATES The number of marks is ...
THE RISE OF GRAPHENE A.K. Geim and K.S. Novoselov
... thinnest flakes are found. A similar approach was tried by other groups (earlier35 and independently22,36) but only graphite flakes 20 to 100 layers thick were found. The problem is that graphene crystallites left on a substrate are extremely rare and hidden in a “haystack” of thousands thick (graph ...
... thinnest flakes are found. A similar approach was tried by other groups (earlier35 and independently22,36) but only graphite flakes 20 to 100 layers thick were found. The problem is that graphene crystallites left on a substrate are extremely rare and hidden in a “haystack” of thousands thick (graph ...
The Chemistry and Applications of Metal
... which revealed 61% porosity and a BrunauerEmmett-Teller (BET) surface area of 2320 m2/g (2900 m2/g Langmuir). These values are substantially higher than those commonly found for zeolites and activated carbon (14). To prepare MOFs with even higher surface area (ultrahigh porosity) requires an increas ...
... which revealed 61% porosity and a BrunauerEmmett-Teller (BET) surface area of 2320 m2/g (2900 m2/g Langmuir). These values are substantially higher than those commonly found for zeolites and activated carbon (14). To prepare MOFs with even higher surface area (ultrahigh porosity) requires an increas ...
purdue university - IUPUI ScholarWorks
... Three parts consist of my thesis work centered on the synthesis of inorganic phosphates and then metal organic frame work (MOF). The first part is the synthesis of mesoporous chromium phosphates using the room temperature solid state reaction (SSR) approach. One of the major aims of this work is to ...
... Three parts consist of my thesis work centered on the synthesis of inorganic phosphates and then metal organic frame work (MOF). The first part is the synthesis of mesoporous chromium phosphates using the room temperature solid state reaction (SSR) approach. One of the major aims of this work is to ...
New Visible-Light Active Semiconductors
... photocatalysts, among others. In particular, oxides with perovskite structure formed by TaO6 or NbO6 octahedra layers have shown the capability to develop an important catalytic activity have reported photocatalytic activity in tantalates and niobates of the type NaMO3 (M ¼ Ta and Nb) for the stoich ...
... photocatalysts, among others. In particular, oxides with perovskite structure formed by TaO6 or NbO6 octahedra layers have shown the capability to develop an important catalytic activity have reported photocatalytic activity in tantalates and niobates of the type NaMO3 (M ¼ Ta and Nb) for the stoich ...
Toward Greener Chemistry Methods for Preparation of
... reactions. The dramatic rate enhancements of these reactions have been explained by means of very well-known Arrhenius law: k = Aexp − Ea / RT ...
... reactions. The dramatic rate enhancements of these reactions have been explained by means of very well-known Arrhenius law: k = Aexp − Ea / RT ...
Thermal Decomposition of Polymers - Marcelo Hirschler
... chemical changes when heat is applied; this will usually result in undesirable changes to the properties of the material. A clear distinction needs to be made between thermal decomposition and thermal degradation. The American Society for Testing and Materials’ (ASTM) definitions should provide help ...
... chemical changes when heat is applied; this will usually result in undesirable changes to the properties of the material. A clear distinction needs to be made between thermal decomposition and thermal degradation. The American Society for Testing and Materials’ (ASTM) definitions should provide help ...
GRAPHITE
... temperatures 4530 - 5430°F (2500 - 3000°C). Under these conditions amorphous carbon transforms to crystalline graphite. Primary synthetic graphite has a high purity: more than 99.5% of carbon. Secondary synthetic graphite. Secondary synthetic graphite is recovered from machining operations of grap ...
... temperatures 4530 - 5430°F (2500 - 3000°C). Under these conditions amorphous carbon transforms to crystalline graphite. Primary synthetic graphite has a high purity: more than 99.5% of carbon. Secondary synthetic graphite. Secondary synthetic graphite is recovered from machining operations of grap ...
Structure and Properties of Polymers
... macromolecule, it can become a trifunctional branch point because three chains can emanate from it. Similarly, a monomer molecule containing two double bonds or four functional groups capable of condensation can give rise to a tetrafunctional branch point in a forming macromolecule because four chai ...
... macromolecule, it can become a trifunctional branch point because three chains can emanate from it. Similarly, a monomer molecule containing two double bonds or four functional groups capable of condensation can give rise to a tetrafunctional branch point in a forming macromolecule because four chai ...
Multiwalled Boron Nitride Nanotubes: Growth, Properties, and
... deformation in BNNTs was predicted through first-principles pseudopotential density-functional calculations. In zigzag BN nanotubes, radial deformations due to transverse pressures of about 10 GPa decrease the direct band gap of BNNTs from 5 to 2 eV, allowing for optical applications in the visible ...
... deformation in BNNTs was predicted through first-principles pseudopotential density-functional calculations. In zigzag BN nanotubes, radial deformations due to transverse pressures of about 10 GPa decrease the direct band gap of BNNTs from 5 to 2 eV, allowing for optical applications in the visible ...
A Review of using Spray Pyrolysis through Sol-gel
... would be NH4·H2PO4.34,35 Two synthesis routes following the sol-gel process were discussed to show that the pure olivine structure could be formed regardless of the different starting materials. The first method involved dissolving stoichiometric amounts of Li (OH)·H2O, FeC2O4·2H2O and NH4·H2PO4 rea ...
... would be NH4·H2PO4.34,35 Two synthesis routes following the sol-gel process were discussed to show that the pure olivine structure could be formed regardless of the different starting materials. The first method involved dissolving stoichiometric amounts of Li (OH)·H2O, FeC2O4·2H2O and NH4·H2PO4 rea ...
Synthesis and Characterization of Amorphous and Hybrid Materials
... which a charged catalytic species, for example an OH- nucleophile or H3O+ electrophile, is attracted to or repelled from potential reaction sites, depending on their charge. The availability of labile protons determines whether anions or cations are solvated more strongly through hydrogen bonding. B ...
... which a charged catalytic species, for example an OH- nucleophile or H3O+ electrophile, is attracted to or repelled from potential reaction sites, depending on their charge. The availability of labile protons determines whether anions or cations are solvated more strongly through hydrogen bonding. B ...
Prohibited and Restricted Materials
... This publication provides an overview of Cummins’ position and standards on Prohibited and Restricted Materials in our processes and products. In this context the term “materials” refers generically to elements, compounds and chemicals. There are many existing and emerging local and regional regulat ...
... This publication provides an overview of Cummins’ position and standards on Prohibited and Restricted Materials in our processes and products. In this context the term “materials” refers generically to elements, compounds and chemicals. There are many existing and emerging local and regional regulat ...
Non-native transition metal monoxide nanostructures
... crystal formation energy, which stabilizes an unstable phase of the nano-structured materials and dominates all of their physicochemical properties.11–14 Importantly, thermodynamically unstable phases can be stabilized by coupling the excess surface energy of nanomaterials with careful control of ki ...
... crystal formation energy, which stabilizes an unstable phase of the nano-structured materials and dominates all of their physicochemical properties.11–14 Importantly, thermodynamically unstable phases can be stabilized by coupling the excess surface energy of nanomaterials with careful control of ki ...
CONDUCTOMETRY
... renewed, this eliminates the poisoning effect. Mercury forms amalgams (solid solution) with many metals. The diffusion current assumed a steady value immediately after each change of applied potential and is reproducible. The large hydrogen over-potential of mercury renders possible deposition of ...
... renewed, this eliminates the poisoning effect. Mercury forms amalgams (solid solution) with many metals. The diffusion current assumed a steady value immediately after each change of applied potential and is reproducible. The large hydrogen over-potential of mercury renders possible deposition of ...
Electrical Effects and Devices/Dielectrics and Insulators
... The characterization of dielectric materials must be carried out in order to determine their properties for various applications over different parts of the electromagnetic frequency spectrum. There are many techniques and methods available for this purpose that are too numerous and detailed to atte ...
... The characterization of dielectric materials must be carried out in order to determine their properties for various applications over different parts of the electromagnetic frequency spectrum. There are many techniques and methods available for this purpose that are too numerous and detailed to atte ...
comparison of candidate materials for seasonal storage of solar heat
... (Thermo Chemical Material) storage system. Of these subsystem models, the TCM storage system is the most complicated one. It consists of two chemical reactors with heat exchangers for the reaction C + heat ⇔ A + B and a separate material buffer for each of the three reactants. By using the configura ...
... (Thermo Chemical Material) storage system. Of these subsystem models, the TCM storage system is the most complicated one. It consists of two chemical reactors with heat exchangers for the reaction C + heat ⇔ A + B and a separate material buffer for each of the three reactants. By using the configura ...
Physical Properties of Food Materials
... and is expressed in units of mass per unit volume. Materials consisting of particles or grains with interstitial air spaces have different values of particle density and bulk density. Materials without internal air spaces, such as fluids and solids, have equal particle and bulk density. Particle den ...
... and is expressed in units of mass per unit volume. Materials consisting of particles or grains with interstitial air spaces have different values of particle density and bulk density. Materials without internal air spaces, such as fluids and solids, have equal particle and bulk density. Particle den ...
Rapid Microwave Synthesis, Characterization and Reactivity
... Powder X-ray diffraction (PXD) was conducted using a Bruker D8 diffractometer (Bruker Corporation, Billerica, MA, USA, Cu Kα source) or a PANalytical X’Pert Pro MPD powder diffractometer (Cu Kα1 source) in capillary mode. The air-sensitive samples were ground into fine powders and placed in 0.5 mm d ...
... Powder X-ray diffraction (PXD) was conducted using a Bruker D8 diffractometer (Bruker Corporation, Billerica, MA, USA, Cu Kα source) or a PANalytical X’Pert Pro MPD powder diffractometer (Cu Kα1 source) in capillary mode. The air-sensitive samples were ground into fine powders and placed in 0.5 mm d ...
Transition metals and coordination chemistry
... The Concept of Coordination Numbers The concept of coordination numbers was an important result of Werner's research. It clearly established the two most important aspects that are required to discuss chemical structure and change: oxidation state and coordination number. The concept of oxidation s ...
... The Concept of Coordination Numbers The concept of coordination numbers was an important result of Werner's research. It clearly established the two most important aspects that are required to discuss chemical structure and change: oxidation state and coordination number. The concept of oxidation s ...
The Mechanism of Electrode Erosion in Electrical Discharges
... electrical parameters are given; further, LYV can be replaced by a constant LY’ when the gap voltage is given and remains constant for different electrode materials, so that v =a’- PT’-ylT ...
... electrical parameters are given; further, LYV can be replaced by a constant LY’ when the gap voltage is given and remains constant for different electrode materials, so that v =a’- PT’-ylT ...
Design of Thermal Interface Material With High Thermal Conductivity
... Th and Tl, respectively. Therefore, thermal resistance R and thermal impedance of a specimen will be calculated by Eqs. 共2兲 and 共3兲, respectively. 2.2 Thermal Interface Material. A TIM usually consists of thermally conductive fillers and a matrix. Fillers transfer heat rapidly, while the matrix f ...
... Th and Tl, respectively. Therefore, thermal resistance R and thermal impedance of a specimen will be calculated by Eqs. 共2兲 and 共3兲, respectively. 2.2 Thermal Interface Material. A TIM usually consists of thermally conductive fillers and a matrix. Fillers transfer heat rapidly, while the matrix f ...
chm 434f/1206f solid state materials chemistry
... • Single crystal (SC) that has been defect modified with dopants - intrinsic vs extrinsic, nonstoichiometry - is the way to control the chemical and physical properties, function and utility • SC preferred for structure and properties ...
... • Single crystal (SC) that has been defect modified with dopants - intrinsic vs extrinsic, nonstoichiometry - is the way to control the chemical and physical properties, function and utility • SC preferred for structure and properties ...