Zeolite inclusion chemistry. Clusters, quantum dots, and polymers.
... metals and six alternating oxygens arranged much like a crown ether), double-six-rings (D6R) and complex 5-1 structures. Other important structural units are the "sodalite cage" (a truncated octahedron) and the "supercage" (a unit with 12.5 A internal diameter). These units are then joined to form o ...
... metals and six alternating oxygens arranged much like a crown ether), double-six-rings (D6R) and complex 5-1 structures. Other important structural units are the "sodalite cage" (a truncated octahedron) and the "supercage" (a unit with 12.5 A internal diameter). These units are then joined to form o ...
Chapter 4
... The best way to identify a redox reaction is to assign oxidation states to all elements in the reaction. If elements show a change in oxidation states when going from reactants to products, then the reaction is a redox reaction. No change in oxidation states indicates the reaction is not a redox rea ...
... The best way to identify a redox reaction is to assign oxidation states to all elements in the reaction. If elements show a change in oxidation states when going from reactants to products, then the reaction is a redox reaction. No change in oxidation states indicates the reaction is not a redox rea ...
Chapter 13 414 13.1 (a) A sand castle represents an ordered
... O2 because it has three atoms per molecule while O2 has only two. 13.20 All these substances are relatively simple in nature and are liquids under standard conditions. Water is the most ordered because of strong hydrogen-bonding interactions which give it a regular structure, so it has the lowest en ...
... O2 because it has three atoms per molecule while O2 has only two. 13.20 All these substances are relatively simple in nature and are liquids under standard conditions. Water is the most ordered because of strong hydrogen-bonding interactions which give it a regular structure, so it has the lowest en ...
Chapter 12 384 12.1 A system is isolated if it exchanges neither
... distance = 2.3 hr 1 hr 12.19 The heat capacity of a calorimeter can be found from energy and temperature data using Equation 12-5, qcalorimeter = Ccal ∆T. Here, the heat released by the combustion process is absorbed by the calorimeter so: - 15.57 kJ ...
... distance = 2.3 hr 1 hr 12.19 The heat capacity of a calorimeter can be found from energy and temperature data using Equation 12-5, qcalorimeter = Ccal ∆T. Here, the heat released by the combustion process is absorbed by the calorimeter so: - 15.57 kJ ...
Chapter 15 Calculations in chemistry: stoichiometry
... The balanced equation shows that 1 mol of phosphoric acid reacts with 3 mol of potassium hydroxide. The amount of each is found using n = cV, where c is the concentration in mol L–1, and V is the volume in litres. n(KOH) = 1.00 × 0.0100 = 0.0100 mol n(H3PO4) = 2.0 × 0.0325 = 0.0650 mol Use n(KOH) pr ...
... The balanced equation shows that 1 mol of phosphoric acid reacts with 3 mol of potassium hydroxide. The amount of each is found using n = cV, where c is the concentration in mol L–1, and V is the volume in litres. n(KOH) = 1.00 × 0.0100 = 0.0100 mol n(H3PO4) = 2.0 × 0.0325 = 0.0650 mol Use n(KOH) pr ...
ch15
... Lead(II) chromate has been used as a bright yellow pigment in some paints. It can be produced by the reaction of potassium chromate with lead nitrate. a Write a full equation for this reaction. b What mass of potassium chromate is required to produce 6.0 g of lead chromate? c Suggest a reason why le ...
... Lead(II) chromate has been used as a bright yellow pigment in some paints. It can be produced by the reaction of potassium chromate with lead nitrate. a Write a full equation for this reaction. b What mass of potassium chromate is required to produce 6.0 g of lead chromate? c Suggest a reason why le ...
Geometrical frustration
In condensed matter physics, the term geometrical frustration (or in short: frustration) refers to a phenomenon, where atoms tend to stick to non-trivial positions or where, on a regular crystal lattice, conflicting inter-atomic forces (each one favoring rather simple, but different structures) lead to quite complex structures. As a consequence of the frustration in the geometry or in the forces, a plenitude of distinct ground states may result at zero temperature, and usual thermal ordering may be suppressed at higher temperatures. Much studied examples are amorphous materials, glasses, or dilute magnets.The term frustration, in the context of magnetic systems, has been introduced by Gerard Toulouse (1977). Indeed, frustrated magnetic systems had been studied even before. Early work includes a study of the Ising model on a triangular lattice with nearest-neighbor spins coupled antiferromagnetically, by G. H. Wannier, published in 1950. Related features occur in magnets with competing interactions, where both ferro- as well as antiferromagnetic couplings between pairs of spins or magnetic moments are present, with the type of interaction depending on the separation distance of the spins. In that case commensurability, such as helical spin arrangements may result, as had been discussed originally, especially, by A. Yoshimori, T. A. Kaplan, R. J. Elliott, and others, starting in 1959, to describe experimental findings on rare-earth metals. A renewed interest in such spin systems with frustrated or competing interactions arose about two decades later, beginning in the 70s of the 20th century, in the context of spin glasses and spatially modulated magnetic superstructures. In spin glasses, frustration is augmented by stochastic disorder in the interactions, as may occur, experimentally, in non-stoichiometric magnetic alloys. Carefully analyzed spin models with frustration include the Sherrington-Kirkpatrick model, describing spin glasses, and the ANNNI model, describing commensurability magnetic superstructures.