Determining the relative atomic mass of lithium.
DETERMINING THE RELATIVE ATOMIC MASS OF LITHIUM BY JAVERIA MASUD 12-O Implementing Before I started my coursework I wrote a risk assessment which covered all the risks and hazards that might take place during the practical and how to avoid them. I know that lithium is a corrosive chemical and reacts vigorously with water to produce lithium hydroxide which is highly flammable. I made a list of all the chemicals and procedures that would take place during the experiment and which of them might affect my final result. To avoid hazards from taking place I wore eye protection at all times. I also wore a lab coat to protect any acid from spilling on my clothes. I did the experiment in 2 different parts. In the first one I produced lithium hydroxide. In the second one I did the titration of lithium hydroxide. From the first experiment, I reacted 0.09g of lithium with 100 cm³ of distilled water to produce lithium hydroxide. As a result I collected 134 cm³ of hydrogen gas. The table below shows the results produced for the second experiment that was the titration experiment. Volume 1 (cm³) Volume 2 (cm³) Volume 3 (cm³) Final 27.0 27.2 26.8 Initial 0.0 0.0 0.0 Titre 27.0 27.2 26.8 From the titration results, I worked out an average of 27.0 cm³ (3 sig. fig). I used appropriate equipment so that I can get accurate final results, as the precision of apparatus
Determining the Relative Atomic Mass of Lithium.
Determining the Relative Atomic Mass of Lithium. To calculate the relative atomic mass, the moles of H2 produced when Li reacts with HCl. Attempt 1 Attempt 2 Attempt 3 Amount of H2 produced. (cm3) 81 74 78 On the first attempt 181cm3 of H2 was collected. The molarity of H2 must be found to enable us to calculate the relative atomic mass of lithium. mole of gas occupies 24dm3 at room temperature and pressure. /24000 x 181 = 0.0075 Moles of H2 2Li(s) + 2H2O(l) --> 2LiOH(aq) + H2(g) The moles of Li that reacted must now be found. This result must multiply this result by 2 as Hydrogen as a gas is a diatomic particle (there are 2 atoms of hydrogen). = 2 x 0.0075 M = 0.0150M Therefore in 1g of Lithium reacts with H2O there is 0.015M moles of hydrogen given off. Relative Atomic Mass = Mass / Molarity Relative Atomic Mass = 0.1 / 0.015 = 6.66 The second attempt 174cm3 of H2 was collected. /24000 x 174 = 0.00731 M 2 x 0.00731 = 0.0146 M Ar = 0.1 / 0.0146 = 6.9 73cm3 of H2 was collected during the final attempt. /24000 x 178 = 0.00748 M 2 x 0.00748 = 0.01496 M Ar = 0.1 / 0.01496 = 6.7 Average Relative atomic Mass = 6.66 + 6.9 + 6.7 = 6.75 3 Titration Calculations. The titration was used to calculate the moles of HCl that was needed to neutralise 25 cm3 of Lithium Hydroxide, LiOH. Attempt 1 Attempt 2 Attempt 3 Average Amount
Development of the periodic table.
Development of the periodic table The periodic table developed gradually by contributions from various scientists. This eventually led to the modern periodic table. . Dobereiner began with the development by grouping elements based on their similarities and classified them using their relative atomic mass. Dobereiner also identified a 'triad' in the list of elements. Calcium, strontium and barium had similar chemical properties. He noticed that the atomic weight of strontium fell midway between the weights of calcium and barium. (Ca 40.1 + Ba 137.5) × 0.5 = 88.7 Sr = 87.6 2. In order of increasing atomic weights, Newlands pointed out that every eighth element had similar properties, e.g. Hydrogen and Lithium (see fig.1). He called this the 'Law of Octaves'. 3. Mendeleev placed elements according to their increase in atomic mass. He left gaps for undiscovered elements. Mendeleev predicted the properties of the unknown elements based on their 'periodic properties', (see fig. 2). Two of these elements he named 'eka- aluminium' and 'eka- silicium'. 4. Reyleigh and Ramsey reported the discovery of noble gases. They positioned them and eventually came to the modern periodic table used today. The difference between Mendeleev's and earlier attempts to classify elements is that Mendeleev's table allowed for and was capable of adjusting to future discoveries. The
How did Chemistry begin?
How did Chemistry begin? Alchemists The alchemists of the 16th and 17th century tried to change one substance into another for the society including changing 'base metals' such as lead into gold. They also discovered arsenic and zinc and others Robert Boyle Robert Boyle was the first to define an element. Priestly and Lavoisier Joseph Priestly was an English chemist - by collecting gas produced when mercury (II) oxide is decomposed by heating, and thus being the first person to isolate elemental oxygen. Antoine Lavoisier was investigating the oxidation of mercury in air. Lavoisier measured the mass of reactants and products in the reaction. He demonstrated that oxygen was the component of air responsible for the apparent increase in mass observed in combustion reactions. Lavoisier's contributed to the Law of Conservation of mass. Davy When the electrochemical cell had only just been invented, Davy began to experiment with electrolysis. Using a battery made from alternating zinc and copper plates in electrolyte solution, he extracted sodium and potassium metals from their molten salts in 1807. Davy has used electrolysis to discover Barium, calcium and strontium. He also discovered magnesium and boron by using potassium, which is more reactive, to displace these elements from their compounds. He also showed iodine to be element and produced some of the first
Flame Test
Flame Test - Portfolio Evidence . Introduction: Type of chemical analysis to be carried out We carried out a test to find what chemicals where present in these 5 samples Sodium Chloride Lithium Chloride Potassium Chloride Copper Sulphate Strontium Chloride 2. Safety points We handled the safety very well in fact we wore safety goggles and took care whilst holding the metal loop. 3. Materials and methods We used a metal loop, Bunsen burner and the 5 chemicals. To do this we needed to; (1) Clean metal loop in blue roaring flame. (2) Dip the metal loop into hydrochloric acid. (3) Place metal loop into the sample, then place the metal loop into the roaring blue flame and note the colour as it happens quickly. 4. Results Chemical Colour Sodium Chloride Yellow Lithium Chloride Intense Red Potassium Chloride Lilac Copper Sulphate Green Strontium Chloride Buckle Red 5. Evaluation I found this experiment simple and very easy to do. It was very interesting to look at the different colours the flame went. I thought that the this was a fair test and it was good to do. Daniel Roche
Flame test
THE FLAME TEST The flame test is a procedure used in chemistry to detect the presence of certain metal ions based on each element's characteristic emission spectrum. The test involves introducing a sample of the element or compound to a hot, non-luminous bunsen flame, and observing the colour that results. Samples are usually held on a platinum wire cleaned repeatedly with hydrochloric acid to remove traces of previous analytes.1 Assessment: This work can be assessed for Data Collection and Conclusion & Evaluation Data Collection: The appearance of compounds, which will be introduced in the flame test: Compound Appearance sodium chloride (NaCl) white, very small crystals potassium chloride (KCl) white, crystalline solid boric acid (H3BO3) white, crystalline solid calcium chloride (CaCl2) white, solid crystals lithium chloride (LiCl·H2O) white, crystalline solid lead carbonate (PbCO3) white, solid barium chloride (BaCl2) white, solid strontium chloride (SrCl2) white, crystalline solid copper sulphate (CuSO4·5H2O) blue, crystalline solid caesium chloride (CsCl) white, solid unknown white, crystalline solid Recorded colors of the element's flame: Compound Colour of the flame sodium chloride (NaCl) orange potassium chloride (KCl) pale orange boric acid (H3BO3) bright green calcium chloride (CaCl2) red-orange lithium chloride
A Brief Account of the Perception of the Atom
A Brief Account of the Perception of the Atom People perception of the atom has changed dramatically through time. One of the main reasons for this was that a man named Democritus (460-370 BC) who was an ancient Greek philosopher came up with a main theory on atoms and what they were, and because he came up with this theory so early in time no one could come up with experiments that could possibly test or put forth his theory. Democritus said a very basic theory of that everything is composed of atoms which are physically indivisible and indestructible. He also came up with brief theories on what atoms look like, he believed the shape of an atom depended on the state of the atom e.g. he thought an iron atom would be solid and strong with hooks which would lock it onto another atom. The word atom its self comes from the ancient Greek word atomos meaning indivisible. Democritus believed that all matter could be dived and sub-dived into smaller and smaller units until eventually there would be something that could be divided no more, an atom. This was remarkable as there was no possible way ancient Greeks could support this by observation or experiment. The understanding of atoms did not process much beyond Democritus’ theory until the English chemist John Dalton (1766-1844) who looked into the theory of the atom and worked out some atomic weights and invented some atom and
Chromatography and Solvents
Chromatography is a method of separating compounds and mixtures so that they can be identified and analyzed. The word chromatography means color writing. There are many kinds of chromatography such as the thin layer chromatography, Partition chromatography, Column chromatography, and Paper chromatography. Chromatography is important in the analysis of processes and materials such as environmental contamination, food, drugs, blood, petroleum products, and radioactive fission products. It has many uses in the rapidly evolving biotechnology industry. The chromatography sorbents help purify problems in the production of drugs. Equipment used for chromatography is essential for chemical laboratories today. With these devices, scientists can identify chemical compounds in complex mixtures such as smog, cigar smoke, and even coffee aroma. Chromatography could be used to show how much of one substance there is in a mixture. Solvents are used to separate mixtures. Some solvents that we see every day are nail polish remover, water, rubbing alcohol, and vinegar. In chromatography, the components go through 2 phases called the mobile phase and stationary phase. The stationary phase may be solid, liquid, liquid supported on a solid, or gel. They may be packed in a column, spread as a layer, or distributed as a film. The mobile phase may be gaseous or liquid. In paper chromatography,
Gravimetric Determination of Phosphorus in Plant Food
Gravimetric Determination of Phosphorus in Plant Food Abstract: Gravimetric analysis can be used to determine the percentage of phosphorus in plant food. A precipitant of know composition is produced and weighed to find percent of phosphorus in compound. From the mass and known composition of the precipitate, the amount of the original ion can be determined. In doing so, percents of phosphorus and average percent phosphorus of sample plant food were determined. Introduction: Gravimetric analysis is a quantitative method of classical analysis. The element to be determined is isolated in a solid compound of known identity and definite composition. The mass of the element that was present in the original sample can be determined from the mass of this compound. Plant foods contain three essential nutrients that are not readily available from soils. These are soluble compounds of nitrogen, phosphorus, and potassium. A typical label on a plant food will have a set of numbers such as 15-30-15. These numbers mean that the plant food is guaranteed to contain at least 15% nitrogen, 30% phosphorus (expressed as P2O5) and 15 % potassium (expressed as K2O). The remaining of the product is fillers, dyes and other anions and cations to balance the charge in the chemical compounds. In this experiment, we will illustrate aquality control analysis for the determination of
Magnesium Oxide Investigation
Stuart Moody 11CR Magnesium Oxide Investigation Introduction: When magnesium is heated it reacts with the oxygen that is in the air around it, the magnesium changes from an element to a compound and new ionic bonds are formed between magnesium and oxygen atoms. The new compound is called magnesium oxide and is a white powder; the mass of the magnesium oxide is greater than that of the magnesium. We want to investigate this reaction; the purpose of our investigation is to find out the relationship between the mass of magnesium heated and the mass of oxygen, which has reacted with it. The reaction we will see is between magnesium and oxygen in order to produce magnesium oxide we then want to find a formula for this reaction. Plan: We are going to repeat our experiment a number of times with differing masses of magnesium in order to get a wider range of results which we can then compare and analyse. Our group decided that it would work better if we ran two experiments at the same time, this will give us better results at the end because we will obtain a greater number of results which will give us more to compare and analyse. We cannot do two experiments with the same or very near masses of magnesium because we need to see a wide range between our results, which we can then use to form a graph. Hypothesis: I think that there will be a direct relationship between the mass
