Dry-heat oven sterilization? 4. Why is it necessary to use bacteriologic controls to monitor heat- sterilization techniques? 5. When running an endospore control of autoclaving technique, why is one endospore preparation incubated without heating?
Observe the color change while it is being heated. After observing the color change, find the mass and moles of the hydrate. Then find the mass and moles of the water eliminated. And lastly find the mole ratio of water to hydrate. For part 2, do the same thing as part 1 except use an unknown hydrate and calculate the percent mass of water in an unknown hydrate.
The change in enthalpy relies on the concentration of the salt solution, because different concentrations will produce different enthalpies. There is an equation to determine how much of this heat energy is lost or gained when a reaction is performed. Q = c m (T1-T2) Where: q is the energy in Joules C is the heat capacity, measured in joules per gram per degree Celsius M is the mass of the solution, measured in grams J is the joules G is the grams of water T is the temperature ΔH=ΔE + PΔV = (q p +w) – w = q p Procedure: 1. Follow instructions 1-9 in Appendix A-1 to initialize the MeasureNet workstation. a.
The dependent variables are the salt freezing, and the time it took to freeze. 2. The experiment’s hypothesis is incorrect. The lower the temperature, the less time it took for the water to freeze. Carmen believed that the more salt, the lower the temperature is.
Begin by adding 1 mL of rubbing alcohol to test tube and attach a thermometer to it. b. Place assembly in water bath and begin to heat beaker c. As isopropyl alcohol begins to boil, bubbles begin flowing from the capillary tube d. While temperature is decreasing, record the temp. when the last air bubble comes out of the capillary tube. e. Let assembly cool down and repeat process two more times.
Hydrates are crystal solids and water. 2. In order to determine the percent composition and the empirical formula of a hydrate, you must know how much water is in the hydrate. As you cannot measure the mass of the water as it gets added to the salt, how can you determine this? By dehydrating it using fire.
There was a low efficiency rate for this experiment; energy was most likely wasted into the surrounding environment when the burner was alight. Possible ways to improve this experiment would be to possibly do the experiment in a more enclosed space, so as to disallow any heat escaping into the surrounding atmosphere. A fume cupboard would be suitable (when it is not turned on) as there is less movement in the air to move the energy from its intended target. The thermal energy was not only going into the water, but the can of the calorimeter became hot too, meaning that the thermal energy was transferred into the metal surrounding the water, and not just the
Hydrate Lab The purpose of this lab is to analyze the percent water in a crystalline hydrate and to indentify the hydrate from a list of possible unknowns. The solid hydrate will be heated to remove the water, and the percent can be found by measuring the mass of the solid before and after heating. The hydrate will be indentified by comparing the percent water in the hydrate with the percent water calculated for the possible unknown. Before the lab there are pre-lab questions: 1. Describe the three general safety rules for working with a Bunsen burner.
DETERMINING THE PROPERTIES OF AN ENZYME I. Abstract Enzymes are responsible for the speed at which chemical reactions they are involved in take place. This experiment determines the effects that concentration, temperature, pH, and boiling have on an enzyme’s ability to perform its work. It is hypothesized that none of these variables will have any effect on the activity of enzymes and these hypotheses are tested using dye-coupled reactions to determine the rate at which peroxidase converts H2O2 into water (H2O) and oxygen (O2). Each hypothesis is subsequently rejected as data suggests that concentration, temperature, pH, and boiling all have an effect on enzyme activity. II.
Care must be taken when squeezing the pipet bulb on the filter pipet. Too much pressure might cause the filter to leak or fall off. Add about 2 mL of fresh tert-butyl methyl ether to the solid in the RB flask, warm briefly, let the solids settle for a minute, and pipet the liquid to the centrifuge tube as before. Again allow the solids to settle briefly in the centrifuge tube, then filter the liquid through the pressure filtration apparatus, into the same 25 mL Erlenmeyer flask. Doing a rinse such as this helps to ensure that any trimyristin that was left behind in the RB flask and centrifuge tube is not lost, thereby helping to ensure that