17 moles The health of bones depends upon a good supply of calcium. If a person consumes 0.06 g of calcium‚ how many moles of calcium did he consume? 1.5x10-3 mol What is the empirical formula of a compound that contains 20% calcium and 80% bromine by mass? CaBR2 Calculate the number of hydroxide ions present in 0.250 mol of Ca(OH)2. 3.01x1023 |What is the volume occupied by 0.25 moles of Nitrogen at STP? | |
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upper atmospheric layer of ozone gas‚ caused by substances formed from breakdown of ozone depleting substances. There are many concerns that the ozone layer is deteriorating due to the release of pollution containing the chemicals chlorine and bromine. These chemicals are called “ozone-depleting substances” (ODS). ODS are
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miniaturization. The importance of molecules in device applications stems not only from their electronic properties‚ but also from their ability to bind to one another‚ recognize each other‚ assemble into larger structures‚ and exhibit dynamical stereochemistry. As a result‚ molecular electronics is currently a very active research field HISTORY Study of charge transfer in molecules was advanced in the 1940s by Robert Mulliken and Albert Szent-Gyorgi in discussion of so-called "donor-acceptor"
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ozone layer is depleting. Ozone depletion occurs when the natural balance between the production and destruction of stratospheric ozone is tipped in favour of destruction. Although natural phenomena can cause temporary ozone loss‚ chlorine and bromine released from man-made compounds such as chlorofluorocarbons‚ called CFCs are now accepted as the main cause of this depletion. These are used as propellants in spray cans and in the making of plastic foam. They are also found in cleaning solvents
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1. Predict the molecular formula of an alkane with 13 carbon atoms. .................................................................................................................................. [Total 1 mark] 2. Bromobutane‚ CH3CH2CH2CH2Br‚ can be reacted with hot aqueous sodium hydroxide to prepare butan-1-ol. CH3CH2CH2CH2Br + OH– → CH3CH2CH2CH2OH + Br– A student reacted 8.72 g of bromobutane with an excess of OH–. The student produced 4.28 g of butan-1-ol. (i) Calculate the amount
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bottom flask. a. The mass of butan-1-ol was measured. b. The flask was fitted with a reflux condenser and a funnel was placed in the top as shown in the apparatus above. 3. The flask was surrounded with a beaker of cold water to cool it during the addition of concentrated sulfuric acid. a. 10cm3 of sulfuric acid was placed gradually in the separatory funnel while carefully swirling the apparatus from time to time. b. The funnel was removed from the reflux condenser and the flask from the water bath
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Constantly my chemistry teacher encourages us to shrink down to the size of an atom and see the world from a subatomic state. I encourage people to imagine themselves as an atom‚ as crazy as it seems‚ and direct their attention to the neoteric world around themselves. One may come to notice that atoms of dissimilar elements have many comparable qualities when looking at them in this light. Any element that one could view is sure to strike one into a state of awe; however‚ selenium is a particular
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environment have resulted in numerous ripple effects including the acidification of the ocean. The ocean is a complex mixture of chemicals primarily consisting of water‚ sodium chloride and trace elements of magnesium‚ sulfur‚ potassium‚ calcium and bromine. Calcium is the most important constituent as it is important in sustaining marine life and plays a role in the chemical balance of the ocean. The acidification of the ocean‚ precipitated by global warming‚ is causing a change in the chemical interactions
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Goals The main goal of this project is to learn how to identify the properties of an unknown ionic compound. In order to do this successfully the group has to use a variety of methods and run several tests on the unknown compound. By doing this the group will be able to identify the different chemical and physical properties of the compound that will help obtain the identity of the specific compound given. The group will devise two syntheses of the compound‚ and compare them for cost effectiveness
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other or if a pattern is represented in the arrangement of the elements. A number of scientists tried different kinds of patterns. For example‚ the German scientist Johann Wolfgang Döbereiner tried grouping the three halogens elements (chlorine‚ bromine‚ and iodine) in a consecutive order of atomic weights. The idea of putting the elements together finally took shape when the two scientists‚ Dmitry Mendeleev and Julius Lothar Meyer successfully arranged the order of the elements by their atomic weight
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