01:160:161 Lecture Notes - Lecture 1: Graduated Cylinder, Purified Water

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1 Sep 2016

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This lab equipment contains deionized water and is used to rinse glassware such as test tubes: wash bottle. This piece of lab equipment is used along with a ring and ring stand to hold a beaker over a flame: wire gauze. This piece of lab equipment has a lid and is made of heat resistant porcelain which allows for heating/melting chemicals such as metals and ores to very high temperatures: crucible and cover. This piece of lab equipment is used with a ring and ring stand to hold a crucible over a flame: clay triangle. What piece of lab equipment would you use to accurately measure liquids: graduated cylinder. When reading a graduated cylinder you get at eye level and view the _____. How many places after the decimal do you round your measurement and what are the units: meniscus, 2 places after the decimal with the last number (hundredths) being estimated, ml.

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Questions are in the data analysis and this is my data

3. After setting up we measured the crucible to weigh 31.353 grams

4. next we measure the mass of the copper chloride hydrate mass using the weigh paper. It came out with a mass of 1.045grams.

Next we put the copper chloride in the crucible

After that we measured them all together and it weighed 32.4 grams.

5. We put the crucible on the clay triangle and did not tilt the lid be cause lab instructor told us not to

6. Next we sparked the flame to the Bunsen burner

7. Now with the Bunsen burner lit we are ready to observe. As the substance started to heat it up it started slowly to turn greenish and then was slowly turning brown. It is turning brown from the outside walls of the substance to the inside. After all the heating it slowly turned a little light brown, but brown.

8. Once heating is completed, turn off the equipment and allow the sample to cool.

a. Turn off the Bunsen burner.

b. Use a pair of crucible tongs to place the crucible on a wire mesh screen on the

bench.

c. With the tongs, move the lid so that it covers the crucible bottom completely.

Allow the sample to cool for about ten minutes.

9. Remove the crucible cover and carefully inspect the sample. If any of the sample has

maintained its initial appearance, reheat the sample until all of it has reacted.

10. After we allowed the sample to cool we then measured it and it had a mass of 32.222 g

11. next we are adding the deionized water to the cooled dried sample. We rinsed out the crucible and added it to the beaker with around a total of 16mL of DI water. Once initially added it was green on the bottom with precipitate was left on the bottom and blue on the top. After we stirred it now it is light blue and clear. It is just really light blue now and clear.

12. we obtained a piece of aluminum wire we coiled it and stirred it. Its turning from blue to greyish color and its fizzing and it getting warmer. After a little bit there is now copper on the bottom of the beaker. They are redish color and the solution on top is also a redish color.

13. we obtained 10mL of 6 M HCl solution. Next we dropped them in and the solution is fizzing again.

14. we put the filter paper on the filter paper and are now filtering the substance.

15. mass of dry watch glass 39.025 grams

16. 39.278 grams and second time was 39.274

The above is what we did in the lab

Down is the question

Today you are going to take a closer look at the light emitted from a wide variety of different types of matter. Before experimenting with these different light sources, make a large table in your lab notebook with columns listing the major regions of the visible spectrum (ROYGBIV). As you collect data by looking at different light sources, you will keep adding rows of observations into this table. The general layout should look something like this: Once you have your lab notebook ready, collect some observations about these different systems by performing the following experiment: At your bench, you should find a small handheld spectroscope through which you can split the visible spectrum apart and carefully observe each color region in the spectrum. For the first light source, set up and light the votive candle inside the metal pan (the metal pan is just to keep wax from dripping all over the benchtop). Then, look through the spectroscope at the burning candle. In your lab groups, predict what you think the emission spectrum will look like from a light source (flame) that is made by burning the ionic compound SrCI_2. With your prediction, provide a molecular-level justification that supports why you think the emission will look the way you predicted. Write the predictions and explanations down in your lab notebook (with a heading/label for your TA - as you should be doing for every activity). Fill a 400mL beaker about % of the way full with tap water and keep it near your area to use as a waste beaker for used matches and burning applicators. You should have a second beaker containing cotton-tipped applicators soaking in deionized (Dl) water (be sure the applicators are NOT placed in tap water). Into the 24-well microplate, add enough of the solid test samples that have been provided in the lab so that the solid just barely covers the bottom of each well. Be sure to record the identity of each solid you test. Note - be very careful not to cross-contaminate between wells as this will significantly skew results (even a single small crystal can cause a large contamination issue). Remove the candle and place the Bunsen burner in the center of the metal baking pan (the pan will help catch any burning solids that drip or spatter from the flame tests you will be performing). Your TA will demonstrate how to light and adjust the burner being used in our labs here at CSU (avoid fireballs in your face or your lab partner- listen to the TA's directions). To observe the flame colors, you will be placing the salts on the end of water-soaked wooden applicators. When placing the applicators into the burner flame, you only have a limited amount of time before the color will disappear and the applicator begins burning so you should be prepared to make observations as soon as you place the applicator into the burner flame. Also, while performing these steps, one member of your lab group should be observing the flame with the spectroscope while another group member handles the actual burning and observes just with their eye. You should record as much information as you can about the burning behavior including color, intensity, and any other details you notice. In your groups, predict what you think the spectrum would look like for a light-emitting diode (LED) light source. LEDs are made up of solid-state materials. What do you expect to see in the spectroscope while looking at a lit LED? Write this prediction down in your lab notebook and be sure to include a heading so your TA can find this prediction while reviewing your lab notebook pages later. Test your prediction by performing the following experiment: Setup the 9V battery and wire leads as shown below - the foam card that the LEDs are mounted may be clamped into a ring stand to hold it upright for easier viewing. Connect the alligator clips coming from the battery one LED at a time. The red alligator clip should be connected to the longer (+) lead of the LED bulb. The black alligator clip is connected to the shorter (-) lead of the LED bulb. If you reverse the wire leads, the LED will not light. Once connected to the battery, note the macroscopic color of the LED bulb that you can see with your eye, then look through the spectroscope at the lit LED bulb. As you examine the LED with the spectroscope, carefully note and rate the relative appearance/intensity of each of the color regions in the visible spectrum (ROYGBIV). After you have collected all your observations, your TA will demonstrate how to use a different type of spectroscope attached to the laptop computers (SpectroVis Plus). After your TA has demonstrated how to use the instrument, collect spectra for all the LED bulbs by following these Identify and write three (3) new and well-thought-out scientific questions related to the light emitted from a firework. For credit, these new questions MUST follow these guidelines: Questions must be molecular-level and focused on the behavior of the chemical components within fireworks Questions should be directly related to the light emission concepts covered in this lab

Hello I need help with the calculations for my data on my Gas Laws Lab report.

My data	Trial 1	Trial 2	Trial 3	Trial 4
Mass Mg (g)	.034	.044	.043
Volume H2 (mL)	35.5	43.5	42.5
Temperature (Â°C)	20	20	20
Atmospheric pressure (mmHg)	29.8	29.8	29.8
Height difference (mmH2O)	20 cm	12.5 cm	15cm

Calculations:

Moles Mg used

Theoretical moles

H2 produced

Vapor pressure of water (mmHg)

Pressure from height diff (mm Hg)

Pressure of H2 (mm Hg)

Pressure of H2 (atm)

Actual moles H2 produced

Percent yield of H2

Experimental R value (LÂ·atm/molÂ·K)

I think once I see how to do the calculations for trial 1 I can do the rest for the other 2 trials.

Below is the procedure for the lab and the calculations if needed.

PROCEDURE: Obtain a 50 ml gas buret, a â00â rubber stopper and a 600 ml beaker. Your instructor will demonstrate the set-up of the equipment. Place approximately 450 ml of distilled water in your 600 ml beaker. Obtain a 2 inch piece of magnesium metal. Record the mass of the magnesium metal. The mass should not exceed 0.050 g. Wrap the magnesium metal with string so that it will hang down in the gas buret. Place the gas buret in a buret holder on a ring stand. Add 8-10 ml of 6 M HCl to the gas buret. Using your wash bottle carefully add distilled water down the side of the buret, being careful not to disturb the hydrochloric acid you just placed in the buret. If done properly, the distilled water will remain âon top ofâ the hydrochloric acid and not mix with it. Continue adding water until the buret is completely filled. Carefully place the magnesium metal so that it hangs several cm down into the gas buret (holding onto the string). Gently insert the stopper into the buret so that the stopper holds the string in place. Check to be sure that an air bubble has not formed at the stopper. If an air bubble is present, remove the stopper, add more distilled water and re-insert the stopper. Using your distilled water bottle, fill the holes of the stopper with distilled water. Place your finger over the stopper holes and invert the gas buret into the beaker so that the top of the buret is below the water level in the beaker. Clamp the buret in place and allow the reaction to proceed. The more dense hydrochloric acid solution will diffuse downward and react with the magnesium metal to produce hydrogen gas. What do you observe suggesting that a reaction is occurring? Your instructor will write the atmospheric pressure on the board for the day. When the reaction is completed, record the distance between the water in the beaker and the solution in the buret (see figure 1, Pht diff). Without moving the buret, read the volume to the nearest Â± 0.02 ml on the buret. This is the volume of the hydrogen gas. Take the temperature of the solution in the beaker. The temperature of the solution is equal to the temperature of the gas. Stir the solution in the beaker. Wait one minute and record the temperature again. If the temperature is not the same, repeat the process until it remains unchanged. Record the temperature to the nearest Â± 0.1 Â°C. Rinse out your glassware and the buret and repeat the analysis two more times, recording the exact mass of magnesium for each trial. If the data appears suspect for any reason, a fourth trial must be done. Enter your raw data into the lab computer before you leave.

CALCULATIONS: We will look at the data in two different ways: 1. Use the ideal gas law to calculate the actual yield of hydrogen gas and compare it to the theoretical yield based on the moles of magnesium used. 2. Alternatively, using the reasonable assumption for this particular reaction that the yield of hydrogen gas is essentially 100%, the value of R can be determined experimentally from the ideal gas law. You cannot use the theoretical value of R to solve for the experimental R value. The stoichiometrically calculated value for moles of H2 must be used in this instance.

01:160:161 Lecture Notes - Lecture 1: Graduated Cylinder, Purified Water

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