CHEM-1411-PY1-General Chemistry
South Texas College
Spring Term 2017
For: Joe Studer, Ph.D.
By: Isaac Lozano
A00492953
Table of contents
Experiment 1. – Mass pag.3
Experiment 1: Mass
Objective: get an accurate amount of matter which can help to indicate the number of molecules and get the number of atoms as well. For determinate, the mentioned is necessary the use of apparatus as a balance triple beam and an electronic balance.
Summary and procedures: the use of the different types of apparatus to get the correct results is always knowing it functionality and the correct significant digits. We always must make sure the balance should be 0.000 g when it is completely empty. In the case of the electric balance, the tray must to be clean and free of water or dirt, this machine is very accurate and precise. In the use of the flask and beaker, those should be cleaned before and after the use, that is how we avoid and create accidents for unknow chemicals or substances that were used before in the containers. Starting with the procedure, first is determine the mass for each balance in use, then record all the necessary data of that.
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The use of the electronic balance should be very careful, it is more precise and accurate and
2. Put the test tube inside a beaker for support. Place the beaker on a balance pan. Set the readings on the balance to zero. Then measure 14.0g of KNO3 into the test tube.
Planning Firstly here is a list of equipment I used. Boiling tubes Weighing scales Knife Paper towels 100% solution 0% solution (distilled water) measuring beakers potato chips Cork borer. We planned to start our experiment by doing some preliminary work. We planned to set up our experiment in the following way.
Plan 1. Collect 4 different sized beakers 2. Boil some water in the kettle 3. Pour 50ml into each beaker 4. After 1 minute check temperature 5.
Start with the hot water and first measure the temperature. Record it. 8. Then pour 40 ml into the beaker. You can measure how much water was used by looking at the meniscus.
One possible source of experimental error could be not having a solid measurement of magnesium hydroxide nor citric acid. This is because we were told to measure out between 5.6g-5.8g for magnesium hydroxide and 14g-21g for citric acid. If accuracy measures how closely a measured value is to the accepted value and or true value, then accuracy may not have been an aspect that was achieved in this lab. Therefore, not having a solid precise measurement and accurate measurement was another source of experimental error.
The procedure for this experiment can be found in Inorganic Chemistry Lab Manual prepared by Dr. Virgil Payne.
The pH meter needed to be calibrated before the titration, and this was done by using coloured standards of pH 4.0, 7.0 and 10.0. The NaOH used within this practical was measured out in pellet form, and the amount needed was 0.4g of 0.1M NaOH. The NaOH was then dissolved into 100ml of distilled water by using a magnetic stir bar and a magnetic stirrer, which mixed the solution for around 120 seconds. After the NaOH had been dissolved, 25ml of 0.1M CH3COOH was measured into a measuring cylinder and was then transferred into a 100ml beaker. This was also placed onto the magnetic stirrer and a clean magnetic stirrer bar was then added to avoid any contamination before the NaOH had been added. The calibrated pH meter was then added to the CH3COOH and the initial pH reading was then taken, which was 2.8pH. By using a p200 pipette, 500µl aliquots of NaOH were then added to the CH3COOH solution, and 30 seconds were left between each aliquot to ensure the pH meter registered the changed pH. The pH of the solution was then recorded on a graph of pH vs volume of 0.1M NaOH added. After this, another 500µl (0.5ml) of NaOH was added and recorded until 40ml had been added (Thorne, A.
Place the container onto the scales and take out all five of the bearings and hold them in your hand whilst pressing the tare button on the electronic balance to take it to zero. Place one of your bearings to see the mass, record it and take it out. Repeat this for each individual bearing making sure to press tare every time to receive an accurate
Weigh accurately about 0.3 g and dissolve in 40 ml of me-thanol. Titrate with 0.1 M so-dium hydroxide.
is impossible to specify a single best method to carry out a given analysis in
Any chips caused by dropping or misuse of the instrument can cause a change in mass. Additionally, when dealing with some liquids there can be a chemical affinity between the liquid and the stem, depending on the material of which the hydrometer is composed. This can cause a buildup of material on the stem, altering the mass and thereby rendering the instrument out of calibration.
Remove the extra solvent on a steam bath under a hood while flushing the flask with N2 gas, leaving the crude extract. Weigh extract.
accurate and reliable [6, 8, 9]. In addition, it has an added advantage if varying
At the same time a balance score card intergraded with Accounting Information System allows the companies to collect rightfull information, analyse the data and make evidence based decisions. (Marr, 2010).
There are many ways to find the weight of analyte mentioned below some are of them: