In Part A of this experiment, you will determine the freezing point of pure stearic acid. To allow students to formulate and test hypotheses. Check your WebAssign account for due dates. If it is too small to read, click on the. The first curve plots time versus temperature of pure naphthalene; the second curve plots time versus temperature of a solution of sulfur in naphthalene. They are Aluminum, Cast iron and Steel.
The blue charge producer has a negative - polarity. On one graph plot the data from the pure water. A percent error calculation can help to measure the accuracy of the experiment. Dissolving sodium hydroxide or ammonia in water produces a basic solution. Materials and Methods: I placed ten drops of each substance into different wells.
I then tested the substances to determine how they react when their natural environments were altered. The experimental approach to test this hypothesis would be to have two separate bodies of water, one with a set ppm of dissolved oxygen and another with an increasing amount of dissolved oxygen. Read the following program prior to completing the lab. Some information has been provided for you, but still needs to be included on your slides. After going for a run, feeling as if one more beat and the heart would project itself out of the chest. The dissolution of a solute with very low vapor pressure, or a nonvolatile solute, raises the boiling point and lowers the freezing point.
The molality is therefore 12. The water level should not be I do not think that equilibrium was reached because the osmotic pressure caused the rubber band to come off the end of the dialysis tubing. It is similar in that it allows water in and out in order to achieve equilibrium through osmosis. The stopper was replaced and the solution was stirred gently until all of the sulfur had dissolved in the naphthalene. Report a mercury spill: it must be cleaned up immediately. Then, this prediction will be compared to the experimentally measured freezing point of the solution.
Similarly, anti-freeze lowers the freezing point and lowers the boiling point. Half-fill the 100-mL beaker with cool tap water. Cell membrane, Concentration, Diffusion 990 Words 4 Pages your own and without assistance, complete this Lab 1 Answer Form electronically and submit it via the Assignments Folder by the date listed on your Course Schedule under Syllabus. Crystal lattice energy is the energy and formation of the crystal from infinitely separated ion. With the raw egg experiments, I believe that a certain element in the eggshell must have bonded with another element in vinegar and left in the form of the bubbles. Supercooling can be minimized by cooling slowly with rapid stirring. The vapor pressure is the escaping tendency of solvent molecules.
The salt water had a lower freezing point than the pure water by 2 degrees which supports the hypothesis that solutions. The pressure of a solution is lower than the pressure of the pure substance because when a solute is present, the surface of the solution is comprised of solute particles and solvent particles, instead of only solvent particles. Which of the following occurs when a hypertonic solution is added to cells? Eye Wash 2 points a. Since the solution is 28. So after I completed this lab, I was asked the following question: What changes would you make, if any, if you did this lab again? Data Table 1: Pure Water and Salt Solution Seconds Distilled H 2 0 Room temp Distilled H 2 0 Ice bath Saltwater Room temp Saltwater Ice bath 0 23 23 17 23 30 23 10 20 7 60 23 4 22 1 90 22. The first is to teach us about freezing points. When the temperature remained constant for several readings, the solution was allowed to cool without further temperature readings.
Queston 2: Using your measured amounts of stearic acid and lauric acid for the first addition, calculate the colligative molality m c of the resulting solution, the freezing point depression ΔT f this molality should cause and the theoretical freezing point of the solution. They are called colligative properties because they are related to the number and energy of collisions between particles and not to what the particles are. Section 3: Procedure In this experiment, I observed substances in their natural state, and recorded their apparent physical properties. By not measuring substances accurately, the calculations could be a bit off. At the freezing point, the kinetic energy of the particles becomes low enough for inter-particle forces to lock the particles into fixed positions in the solid crystal structure. The experimenter should become familiar with basic operations necessary. On the other hand, if a cell is placed into a salt solution in which the salt concentration in the solution is higher than in the cell, the solution is said to be hypertonic.
At this moment, the gaseous and liquid states of the solvent are in dynamic equilibrium and the molecules change from the liquid to the gaseous states and from the gaseous to liquid states at equal rates. The reaction is called exothermic. Adding molasses or honey to water produces a solution more viscous than water. Students will fill out the lab worksheet which will help guide them in the lab. The lab will open in the Calorimetry laboratory with a calorimeter on the lab bench and a sample of sodium chloride NaCl on the balance. Falk Chemistry 09-13-13 Title: Properties of Gases Purpose : The purpose of this lab was to learn about properties, both physical and chemical, of gases and to be able to identify them. Transfer some liquid into a beaker and pipet out of that.
This is shown in Figure 3. If either acid is spilled on skin, wash the affected area with soap and water. Two ice baths were made, one with pure water, the other with salt water. Another way to think about freezing point depression is to consider the solid surface area available to the solvent molecules. How can it be minimized? Solute particles are present at the liquid-solid interface, effectively decreasing the surface area of the solid accessible to the solvent molecules. Chemistry: The central science: laboratory experiments, eighth edition.
The atomic theory of matter offers explanations for bonding and physical phase. Do part 2 first and repeat it again last. Once you have measured K f for a solvent with one solute, you can use and the same value of K f for other solutes. To extract a unique freezing point from the rounded corner on the plot, straight lines are drawn that extend the steeply falling part and the nearly horizontal part of the curve. Water will move from the solution into the cell, causing lysis of the cell.