Investigation to determine the Relative atomic mass of Li

Investigation to determine the Relative atomic mass of Li Results and calculations for the first method. Mass of Li used : 0.12g Start volume of Water : 55.5ml Final volume of water : 250.0ml Volume of hydrogen produced : 194.5ml Now based on these results I t is possible to calculate the concentration of the limewater. Calculate the number of moles of hydrogen produced: We have 195ml of hydrogen that has been produced. - This is equal to 0.195 dm3 Since 24dm3 is one mole of hydrogen at room temperature. - 0.195 dm3 = 0.008125 mol Calculate the number of moles of Li reacted: Using the equation: 2Li (s) + 2H2O (l) --> H2 (g) + 2LiOH (aq) 2 : 1 One can see the reacting ratio is 2:1, the no. moles of Li will be twice that of H2. - Moles of Li = 2 x 0.008125 mol - Moles of Li = 0.01625 mol Calculate the relative atomic mass of Li: As the mass of Li and No of moles used are know, it is possible to calculate the relative atomic mass of Li. - Mass of Li = 0.12g - No Moles of Li = 0.01625 mol - Relative atomic mass = mass/no moles - 0.12/0.01625 = 7.3846 - Relative atomic mass of Li = 7.38 Results and calculations for the second titration method. 2 3 End Burette vol (ml) 46.70 43.95 43.70 Start Burette vol (ml) 06.50 01.65 01.30 Amount used (ml) 40.20 42.30 42.40 Using the two best titres (within 0.1 ml),

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Investigation of Enzyme Activity

An Investigation of Enzyme Activity with different Substrate Concentrations. Aim To investigate how different concentrations of substrate affects the rate of enzyme activity. Objective My objective is to determine how different concentrations of substrate, affects the rate of enzyme activity. I will do this by using different concentrations of Hydrogen Peroxide, and mixing it with the enzyme catalyse. Then I will measure how much gas is produced. Theory What is an Enzyme? Enzymes are proteins which are biological catalysts. A catalyst in chemical terms substantially reduces the energy barrier which exists between atoms and which prevents the atoms from getting close enough to react and form a bond with one another. An enzyme lowers the energy of activation of a reaction but the catalyst is not changed in any way in the process .Therefore, when the atoms of molecules are acted upon by enzymes, an identical reaction occurs as would have occurred without the enzyme but, the energy hill required to overcome the getting-close barrier, is much, much smaller than would have been true without the enzyme's help. The structure of the enzyme is such that atoms of molecules can get close enough to interact, but the energy required to allow this closeness is relatively small. Its like going into an empty closet with someone relative to going into an empty auditorium with someone.

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Determining the concentration of acid in a given solution

Determining the concentration of acid in a given solution Planning 4 I have been given a sample of sulfuric (VI) acid solution with a concentration between 0.05 and 0.15 mol dm-³. I am going to find out the accurate concentration of the sulfuric acid. To find out the concentration of the acid I will react it with a known volume and concentration of a base and see how much base was needed to neutralise the acid. The acid is a strong acid which means that I know all the H+ ions have been disassociated and are in the solution. The H+ ions will react with the OH- ions in the alkali which will neutralise the solution. I am provided with solid, hydrated sodium carbonate with the formula Na2CO3·10H2O.1 This is a readily available base and I can dilute it down to achieve the concentration I want to react with the acid. The formula of the reaction that will take place is H2SO4 (aq) + Na2CO3 (aq) --> Na2SO4 (aq) + CO2 (g) + H2O (l) So 1 mole of H2SO4 reacts with 1 mole of Na2CO3. A titration will give me the most reliable and accurate results with the available equipment. To do my titration I will need: A Burette 7 I will need a burette to add the sodium carbonate to the sulfuric acid solution. The burettes provide me with very accurate results of volume of solution added. The class set of burettes measure 50cm3. I want to do a titration

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Deducing the quantity of acid in a solution

Sofia Gaggiotti Chemistry coursework: Deducing the quantity of acid in a solution 20/03/2008 Index Aim and Background information 3 Hazards 3 Protection 4 Method 5 Previous calculations 5 Making the Solution 6 Equipment needed 6 Quantities of materials needed 8 Procedure 8 Making the Titration 9 Equipment needed 10 Procedure 13 References 15 Results and calculations 16 Evaluation 19 Chemistry coursework: Deducing the quantity of acid in a solution Aim and background information The aim of this experiment is to find how to develop and determine an accurate, precise and reliable concentration of an acid rain solution. 1 To do this, we are going to make first a solution of sodium carbonate with distilled water and then a titration in order to calculate the concentration of sulphuric acid in a solution. Solution: a solution is a homogeneous mixture composed of two or more substances. In this mixture, a solute is dissolved in a solvent. Solutions are characterized by interactions between the solvent phase and solute molecules or ions that result in a net decrease in free energy. 2 Titration: a titration is a laboratory technique by which we can determine the concentration of an unknown reagent using another reagent that chemically reacts with the unknown. At the equivalence point (or endpoint) the unknown reagent has been reacted with the known reagent.

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