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GCSE: Classifying Materials
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How to tell if something is ionic
- 1 Ionic compounds have strong electrostatic attractions between their positive and negative ions. These take a lot of energy to break, so will have a very high melting and boiling point.
- 2 Ionic compounds can conduct electricity when dissolved in solution as their ions are free to move and carry charge. When they are solids, however, their ions are held in a fixed lattice so they cannot move and conduct electricity.
- 3 Ionic compounds are soluble in polar solutions like water. They are insoluble in organic solvents like cyclohexane.
- 4 Ionic compounds all form crystal salts. If these are hydrated they will often be brightly coloured. If they are not hydrated they will usually be transparent or white.
- 5 Ionic compounds are made from metal cations bonding to non-metal anions in a giant lattice.
How to tell if something is a giant covalent
- 1 Giant covalent compounds are held together by incredibly strong covalent bonds. These take a lot of energy to break, so will have an incredibly high melting and boiling point.
- 2 Giant covalent compounds do not have anything to carry charge (such as ions or delocalised electrons) so will not conduct electricity. The exception to this rule is graphite, as this has delocalised electrons so can conduct.
- 3 Giant covalent compounds are insoluble in both polar and non-polar solvents. This is because their strong covalent bonds are too strong to be broken by the solvent.
- 4 The three main forms (allotropes) of carbon that are giant covalent compounds are diamond (a beautifully shiny rock), graphite (which looks like the tiles on our roofs) and fullerines. Fullerines have a “football” shape.
- 5 Apart from allotropes of carbon, the most commonly occurring giant covalent compound that crops up in exams is SiO2.
How to tell if something is a simple covalent
- 1 Simple covalent compounds are held together by weak van der Waals forces. These take little energy to break, so have a very low melting and boiling point.
- 2 Simple covalent compounds do not have anything that can carry charge (like ions or delocalised electrons), so they cannot conduct.
- 3 Simple covalent compounds are soluble in non-polar solvents, and insoluble in polar solvents like water.
- 4 Due to their low melting and boiling point, most simple covalent compounds are liquids or gases at room temperature. The halogens will give coloured gases- Cl is pale green, Br is orange, I is an almost black solid which sublimes to a purple gas.
- 5 Simple covalent compounds are made from a non-metal bonding to a non-metal.
Our experiment consisted of two samples of water containing unknown substances, and our objective was to identify the compound present in the substance.
This is why in kettles, where water is heated, calcium carbonate forms as scale. Chemical descalers contain a weak acid which reacts with the calcium carbonate. Permanent hardness of water is caused by dissolved calcium sulphate and magnesium sulphate. As you've probably guessed, this type of hardness cannot be removed easily (i.e. boiling). Instead, it has to be removed by chemical treatment. Hardness in all types of water can be removed by distillation. However, this is not a process used in the real world on a large scale. Permanent and temporary hardness can be removed by using washing soda (sodium carbonate crystals).
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Identifying unknown substances. The test that we did was a flame test, negative ion test and a alcohol test. We also did chromatography to find out which technician labelled the bottle.
Not completely, of course, of even near complete 6. full- about half an inch of water 7. And wait There are two parts in naming a chemical Name of the chemical negative ion Flame test To find the first part of the name of the chemical you have to do a flame test. A flame test is used to indentify the names of the metal by the colour that is produces. 1. Use a wire called nichrome so that the wire does not produce colour to the flame 2. dip a nichcrome wire into the hydrochloride acid to clean it 3.
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USES: Hearing Aids, watches, pacemakers, calculators Impact on Society * Major impact on society has been the portability of this battery. As the battery is small and has a light weight it has enabled the greater use of electrical appliances in society * Light weight, small size, long life span and stable voltage of a period of time, useful in many small appliances * Silver button cells are increasingly used in medical devices such as pacemakers and hearing aids Environmental Impact * zinc is a heavy metal and in large quantities can have devastating effects.
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Elemental mercury exists as a silvery liquid and an odourless vapour at room temperature. It is eliminated in urine, faeces, saliva, and sweat and by exhalation when it is taken in by the body. How is Hydrochloric acid disposed of: - Small amounts of dilute hydrochloric acid can be flushed down a sink with a large quantity of water, unless local rules prohibit this. Larger amounts should be neutralised before disposal. Concentrated acid should not be flushed down a sink but should be neutralised first.
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Then mark on the underside of the plate four quadrants which can be seen through the translucent jelly. Using a cotton swab, distribute the bacteria throughout the plate, then discard the swab. Then place a label on the cover, which states where each disinfectant will be placed, preventing any confusion. Then get some paper discs and using forceps, place them in the various disinfectants. The place them on the plate and cover and seal the dish. Give the plate to the teacher, which will then incubate the plate at a constant temperature of 20�C for 48 hours.
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Distilled water was used to dampen the red and blue litmus paper 3. Matches was used to light the Bunsen burner 4. Using the flame of the Bunsen burner the splint was lit and then blown out leaving a glowing splint 5. The tongs was used to hold the test tube "A" over the lit Bunsen burner and the blue and red litmus paper was held at the opening of the test tube 6. The glowing splint was then placed inside test tube "A" 7.
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and xylene cyanol (C25H27N2NaO6S2) are separated through the use of water as a solvent. Aim-To determine which dye in screened methyl orange is more soluble in water. Apparatus-screened methyl orange, chromatography paper (10cm X 2.5cm), 250cm3 beaker, fine dropper, retort stand. Method- 1. A horizontal line was drawn on the chromatography paper 1.5cm above the bottom line 2.
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Find the total mass of the magnesium ribbon, crucible and the lid. Note the appearance of the magnesium. 3. Place the crucible (with the lid on) on a pipe clay triangle supported on a tripod. Heat the crucible with a strong Bunsen burner flame. 4. Lift the lid carefully with tongs every 10 seconds to let the air enter the crucible. Keep heating the crucible until the reaction is complete.
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The clarity of diamonds makes it extremely suitable for making materials that require pure and clear screens to reflect light. Since synthetic diamond is the cheapest and hardest material in the world, making it worth the cost of producing. There are two ways to make synthetic diamonds. With high pressure and high temperature or with chemical vapor deposition, a method of creating a carbon plasma on top of substrate onto which the carbon atoms deposit to form diamond. Diamond, with its hardness and clarity, has influenced our lives in many ways.
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Tine layer and paper chromatography experiment. The aim of the investigation was to determine the quality of the water that contains chemical dye pollution. To begin the investigation firstly we put a line on the tine layer paper
These two methods is a useful because it is relatively quick and requires small quantities of material. The aim of the investigation was to determine the quality of the water that contains chemical dye pollution. To begin the investigation firstly we put a line on the tine layer paper and carefully a spot on the stationary phase. In to the beaker mixing two different chemical, methanol and ethanol then placed the paper in to the beaker. And leave the paper about 10 minute, until the solvent move up. Finally different components of the mixture moved up at different rates.
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So even though we well-planned the procedure and were with good hypothesis and prediction, we could not get better result as we did not use materials accurately. Therefore, to perform the improved experiment and get a better result next time, we have to be more prepared in materials, in planning, in predicting, and in performing the experiment, without having a mistake. Introduction (Jasmine Yu) Acids and bases can be found in everyday household appliances and can be used in many different ways, for instance "the phosphoric acid in Coca-Cola is able to remove rust" (Whitehead, 2008).
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Water is commonly used as a solvent; this dissolving process is called hydration. The heat involved in a chemical reaction, at constant pressure is referred to as enthalpy and usually refers to the"...amount of energy released for one mole of the ion dissolved in a large amount of water forming an infinite dilute solution in the process."1 Enthalpy change in a solution is shown by the equation where the overall positive or negative energy depends on the values of each trial.
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Using the concentration and liters needed during the titration to react the number of moles of unknown can also be calculated. To determine the percent oxalate the end point of the titration is reached and recorded, once the solution has changed color according to the indicator in the an acid/base reaction, or a precipitant is formed in a double , single/ replacement reaction or Redox. Percent by mass can then be determined through stoichiometric calculations using the concentration, moles, liters and molar weight of the known and unknown compounds.
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50cm3 of hydrochloric acid is added to beaker with eggshell and stirred with glass rod 5. Stirring is continued until eggshells stop producing bubbles indicating that no more eggshell can be dissolved 6. Mixture is filtered for a day and the residue of eggshell is left in filter paper 7. Residue is left to dry ,and the mass of the filtrate along with the residue and dry filter paper is recorded 8. The residue is removed and the mass of the filter paper is recorded. Results Mass of eggshell=27.55g Mass of filter paper + egg-shell residue= 15.6g Mass of filter paper without residue=2.06g Calculations 1.
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Eventually the particles are evenly spread and the concentration is equal. * Diffusion does not happen in solids * Diffusion is the way we smell things from far away The Atom * Atomic (proton) number gives the number of protons * An atom is neutral so the amount of protons and electrons are the same * Mass number gives number of protons and number of neutrons * Isotope are elements that can exist in more than one form * Atoms are found as compounds in nature because they are unstable without a full outer shell Substances with ionic bonding * Usually involves a metal and non metal * Element far apart
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3. Add about 10cm3 of concentrated hydrochloric acid to the beaker, and cover it with a small watch glass. Place the beaker inside a 250-cm3 beaker which is about 1/3 full of water (refer to the diagram below). Heat this water bath to boiling until a solid material forms in the small beaker. 4. Cool the small beaker in an ice-water bath until the amount of solid formed is constant. 5. Filter off the solid formed by suction filtration, washing any solid from the beaker onto the filter paper. Use a small amount of chilled distilled water for the purpose of washing. 6. Stop suction by lifting the Buchner funnel. Wash the solid with a little chilled distilled water.
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Small, medium, large) of tights The one factor I will be changing in my test is the denier of tights. To make sure my results are dependable, I will repeat the experiment three times for each different type of tights and then work out the average. The apparatus I will need to use to carry out this test are: * Clamp and stand * Newton weights * A weight holder * Ruler * Bulldog clips * Samples of 15 and 40 denier tights Below is a diagram of the apparatus I would use and how I would set up the experiment: It is important that I make sure my experiment and working area is safe.
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Results; Elements Symbol Observations Calcium Ca Flame turned orange red Potassium K Flame turned pink orange Sodium Na Flame turned bright orange Iron Fe Flame immediately turned into orange sparks Copper Cu Flame turned into neon green blue Testing for positive ions: To show the presence of various positive ions. Method; * 1cm3 sodium hydroxide is added to 1cm3 ion solution Results; Positive ion (in solution) Effect of adding sodium hydroxide Calcium This liquid turned into White precipitate. Potassium No reaction occurred.
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Aim: To determine the difference in percentage mass increase when dried spaghetti, is rehydrated for different lights of time. Hypotheses: I hypothesize that if spaghetti is heated for a longer period if time, the mass would increase at 15 grams per minute at a constant rate; because of the heat increases the kinetic energy of the water molecules there for allowing them to have a better chance of collision wit the dry spaghetti. This faster movement of water molecules driven by higher kinetic energy would increase the rate of osmosis.
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Apparatus Equipment * Retort stand * Universal Clamp * Fishing Wire * Weights (100g) * Clamp * Mat For Floor Safety * Make sure there is space to work * Keep clear of mat so the weight doesn't hit your feet * Clear the area Method 1. Put the retort stand on the edge of the table 2. Clamp it down so it is unable to topple over 3.
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However, many restaurateurs rejected Prof Wiseman's suggestion. Mary Ann Gilchrist, head chef of Carlton Riverside, Llanwrtyd Wells, Powys, said she would not be removing salt cellars from her restaurant. She said, "I have read all the information about salt but I still think people should have the right to choose whether they season their food or not, although I do like to see people taste their food first before adding salt. "I hate going into restaurants where there is no salt available on the table.
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Reactivity series: (least) Au, Ag, Cu, Pb, Sn, Fe, Zn, Al, Mg, Ca, Na, K (most) Colour: Certain metals are certain colours. Because of this we could eliminate certain metals that are not that colour. Eg: A metal cannot be Ag (silver) if its colour is gold. pH: Certain metals have a certain pH. We could eliminate certain metals, if, for example, it was alkali. If the metal was alkali (pH 8 - 14) it would be most likely to be a metal from the Group 1 and 2 metals (the alkali metals and the alkali earth metals).
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In liquids their particles are continually moving at various speeds, which then collide in different ways. There are different ways of collisions occurring which have different effects such as 'head on' and 'glancing' collisions. The particles that contain a lot of kinetic energy (at a high temperature) collide with a large force therefore gain a heavy contact with another particle (head on). This is known to be successful and a reaction takes place. Where as a 'glancing' collision the particles have not got enough kinetic energy (at a low temperature) to produce a reaction because the contact is not great enough, so a reaction will not occur.
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Reactions in which the activation energy is high are very slow at room temperature, because only a very small fraction of collisions have enough energy to overcome the activation energy. The success rate of collisions is low. One of the ways to increase the rate of reaction would be by adding a catalyst, this would enable particles a boundary where they can collide against each other. A use of a suitable catalyst may allow particles to react even if they collide with little energy therefore more successful collisions are likely.
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