9378218
Description
Flashcards by Noah Bryan, updated more than 1 year ago
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Created by Noah Bryan
almost 7 years ago
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| Question | Answer |
| Measuring the Molar Volume of a Gas | ... |
| What safety precautions should be taken? | Wear eye protection Ensure the delivery tube does not become blocked Ethanoic acid will sting if it gets into cuts in the skin. |
| Draw a Diagram of the required equipment: | |
| Describe the Procedure | 1) Place 30cm^3 of 1moldm^-3 ethanoic acid in the boiling tube. 2) Set the apparatus up 3) Place approx. 0.05g of calcium carbonate in a test tube. 4) Weigh the test tube and its contents accurately 5) Remove the bung from the boiling tube and tip the CaCO3 in. Quickly replace the bung in the boiling tube. 6) Once the reaction is over, measure the volume of gas collected in the measuring cylinder 7) Reweigh the test tube that had contained the CaCO3 8) Repeat the experiment 6 more times, increasing the mass of CaCO3 by about 0.05g each time. Do not exceed 0.4g of CaCO3. |
| What does the graph look like? Label the axes | |
| What's the equation for ethanoic acid and calcium carbonate | 2CH3COOH+CaCO3--> Ca(CH3COO)2+H20+CO2 |
| Why is it more accurate to find the CaCO3 by weighing the test tube with it in then tipping it out and reweighing the test tube than to weigh the empty test tube at the start. | There will always be a bit of CaCO3 left behind in the test tube, so reweighing it after will make sure anything left in the test tube will be accounted for. It will indicate how much of the CaCO3 is actually used. |
| Identify the major source of error caused by the procedure used. | Loss of gas during the time to place the bung over the test tube. |
| What change to the procedure or apparatus could be made to eradicate this error? | Use a flask with a side arm with the acid in it which pours onto the solid so it is always sealed. |
| Find the concentration of a solution of NaOH | ... |
| Safety Precautions | Wear Eye protection Sulfamic Acid can be toxic if it's ingested Ensure the burettes are filled when the top is below eye level. |
| Procedure: | 1) Dissolve 2.5g of Sulfamic Acid in 100cm3 of water. 2) Transfer the solution including washings into a 250cm3 volumetric flask and make the solution up to the mark with distilled water. 3) Prepare your apparatus for the titration. The burette will contain the acid and the conical flask will contain the NaOH solution 4) Pour a 25cm3 aliquot of NaOH solution of unknown concentration into the 250cm3 conical flask, add four drops of methyl orange indicator to the conical flask. 6) Titrate the contents of the flask with the Sulfamic acid. Burette readings should be read to the nearest 0.05cm3. Continue to conduct titrations until you have two concordant titres. 7) Record your results in a table. |
| Why should the pipette be rinsed with the NaOH solution after washing it with water? | So there is no water changing the concentration of NaOH. |
| Why is there no need to dry the conical flask after washing it out between trials? | Water is neutral so it won't change number of moles of NaOH put in the flask. Moles are the quantity we are considering so if that doesn't change, it's okay to not dry the conical flask. |
| Find the concentration of solution of HCl | ... |
| Safety: | Wear Eye protection Phenolphthalein solution is flammable and toxic Bench HCl is an irritant Fill burette safely |
| Procedure: | Put 25cm3 of 1 molar HCl in the conical flask. NaOH in burette |
| Hydrolysis of Halogenoalkanes | ... |
| Safety: | Wear Eye protection Halogenalkanes are flammable and harmful Ethanol is flammable AgNO3 is corrosive Use a kettle for hot water rather than a Bunsen Burner. |
| Procedure #1: | 1) Set up a temperature to 50C. Fill the 250cm3 beaker up to 3/4 of its total volume. 2) Fill 3 test tubes each with 5cm3 of ethanol. Now add 4 drops of 1-iodobutane to the first tube. Then 1-bromobutane. Then 1-chlorobutane. 3) Label the test tubes. Loosely place a bung in each test tube. Place the test tubes in the water bath. 4) Pour 5cm3 of AgNO3 into 3 clean test tubes. 5) When the halogenoalkanes - ethanol solutions have reached the temperature of the water baths, add the AgNO3 solution to one of the test tubes and start the stopwatch. 6) Measure the time taken for the precipitate to appear and Repeat. |
| Procedure #2: | Repeat the process with 1-bromobutane;2-bromobutane; 2-bromo 2-methylpropane |
| Reactivity: | Iodoalkanes are the most reactive of the primary alkanes Primary Alkanes are the most reactive (Tertiary is the most stable) |
| CH3CH2CH2CH2Br+ H20 ---> | CH3CH2CH2OH+ HBr (aq) |
| Hwy is water used as the nucleophile rather than OH- ions? | OH- is too strong a nucleophile so water is used so the reaction can be more accurately measured. |
| Why is ethanol used in this reaction | As a solvent - to ensure the two layers are miscible. |
| Investigate the oxidation of ethanol | ... |
| Safety: | Eye Protection Ethanol is flammable Acidified Sodium Dichromate is corrosive and a carcinogen Wear chemical resistant gloves |
| Draw the Diagram: | |
| Procedure: | 1) Place a few antibumping granules in a 50cm3 pear shaped flask 2) Add 10cm3 of acidfied sodium dichromate to the flask. 3) Set the flask up for reflux. 4) Mix 2cm3 of ethanol with 5cm3 of water 5) Place the flask in a beaker of iced water and add the ethanol solution drop wise down the condenser into the flask slowly. 6) When all the ethanol solution has been added, heat the flask gently with a small Bunsen flame so that the solution boils for approximately 10 minute. Allow the apparatus to cool. 7) Distil. |
| Distillation apparatus | ... |
| Test performed on the distillate: 1- pH 2- Add a few drops of acidified sodium dichromate solution to 1cm3 of the distillate and warm in a 60C water bath 3- Add a quarter of a spatula of CaCO3 to 1mc3 of the distillate. 4- Add magnesium strip 5- Add Fehling's solution and warm. | Results: 1- Weak Acid 2- No Reaction 3- Effervescence 4- Mg dissolves 5- No change |
| CH3CH2OH+2[O] ---[H+]--> | CH3COOH + H2O |
| 2CH3COOH+Mg ---> 2CH3COOH+ CaCO3 ---> | Mg(CH3COO)2+ 2H2(g) Ca(CH3COO)2 + H2O + CO2 |
| Investigate the chlorination of 2-methylpropan-2-ol | ... |
| Safety: | Eye protection 2-methylpropan-2-ol is flammable and harmful Conc. HCl is corrosive and the HCl (g) produced are toxic and corrosive 2-chloro2-methylpropane is flammable CaCl2 is an irritant |
| Procedure: | 1) Pour 20cm3 of 2-methylpropan-2-ol and 70cm3 of concentrated HCl into a large conical flask. Place th bung in the mouth of the flask. 2) Swirl; when the contents are mixed, release the pressure. 3) Continue swirling with the bung fitted, releasing the pressure occasionally for around 20 minutes. There will be layers in the flask with the top layer being the crude product. 4) Add approximately 6g of anhydrous CaCl2 and swirl until dissolved, this ensures that any unreacted alcohol is in the lower aqueous layer. 5) Transfer the reaction mixture to a separating funnel. Allow the mixture to settle into two layers then run off the bottom aqueous layer. Retain the upper layer in the separating funnel. Ensure the lid is off during the discarding process. 6) Add approximately 20cm3 of NaHCO3 to the separating funnel. Swirl the funnel and remove the bung to release the pressure that's caused by the production of CO2. Run off the lower aqueous layer. 7) Repeat washing with NaHCO3 (Step 6) |
| Procedure continues.... | 8) Run off the organic layer into a small conical flask; add a spatula of anhydrous NaSO4. PLace the bung in the flask and swirl the contents; leave mixture until the mixture looks completely clear - swirling occasionally. 9) Decant the organic liquid into a 50cm3 pear shaped flask. 10) Set the flask up for distillation 11) Collect the fraction, boiling between 50 - 52C 12) Place pure product into a label sample tube. |
| How would you test for the product that's made? | Add 5cm3 of ethanol and NaOH. Warm. Add excess HNO3 then AgNO3 White Precipitate |
| CH3CH2(CH3)(OH)CH3+ HCl ---> | CH3CH2(CH3)(Cl)CH3 + H2O |
| What is removed from the crude product when it is shaken with NaHCO3? | Unreacted HCl NaHCO3+HCl ---> CO2 + H2O + NaCl |
| Identify unknown organic liquids and inorganic solids | ... |
| Safety: | Eye Protection Unknown organic liquids must be treated as harmful and flammable Inorganic solids regarded harmful KCr2O7 is corrosive, oxidising and carcinogenic KMnO4 is oxidising Ethanol is flammable AgNO3 is corrosive Chlorine water is toxic Dilute ammonia gives off and irritating gas |
| Procedure #1: | 1) Perform the following tests on each of the organic liquids: Place 10 drops of each organic liquid into each of three test tubes and: 1- add 1cm of bromine water - shake 2 - add acidified potassium dichromate and warm to 60C 3- add Fehlings and heat 4- Add ethanol and sodium hydroxide and warm then dilute HNO3 and AgNO3 |
| Procedure #2: | To each of the inorganic solids: 1- Conduct a flame test 2- Dissolve in distilled water then add dilute HNO3 and AgNO3 then dilute NH3 3- Dissolve in dilute water, add dilute HNO3 and BaCl2 4- Dissolve in distilled water then add chlorine water |
| Calculate the enthalpy change for the thermal decomposition of KHCO3 | ... |
| Safety: | Eye Protection 2molar HCl is an irritant K2CO3 is an irritant |
| Procedure: | 1) Place approximately 3g of solid K2CO3 into a test tube. Accurately weigh the test tube and its contents 2) Use the burette to dispense 30cm3 of 2 molar HCl into a polystyrene cup, which is supported in a 250cm3 beaker 3) Measure the temperature of the acid. 4) Continue measuring the temperature whilst adding K2CO3 to the acid and stirring. Record the highest temperature reached 5) Reweigh the empty test tube. 6) Repeat steps using KHCO3 and record the lowest temperature reached. |
| K2CO3 + 2HCl --> | 2KCl + CO2 + H2O |
| KHCO3 + HCl --> | KCl + CO2 + H2O |
| How would use the results to calculate the enthalpy change of decomposition of potassium hydrogencarbonate? | Construct a Hess cycle using the two equations for the experiment reactions and the thermal decomposition of potassium hydrogencarbonate |
| Why is it not possible to measure the enthalpy change of decomposition directly? | It's difficult to control temperature as you are heating constantly, it's also difficult to measure the temperature of a solid |
| Explain why reactions are conducted in a polystyrene cup rather than a glass beaker | They are much better insulators so they reduce energy loss/absorption |
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