n (3) Solutions of aqueous sodium hydroxide and hydrochloric acid react to form water and aqueous sodium chloride. co NaOH(s) → Na+(aq) + OH–(aq) ∆H1 = ? Chemistry with Vernier py In this experiment, you will use a Styrofoam-cup calorimeter to measure the heat released by three reactions. One of the reactions is the same as the combination of the other two reactions. Therefore, according to Hess’s law, the heat of reaction of the one reaction should be equal to the sum of the heats of reaction for the other two.
Objectives: The purpose of this lab is to observe the reaction of crystal violet and sodium hydroxide by looking at the relationship between concentration and time elapsed of the crystal violet. CV+ + OH- CVOH To quantitatively observe this reaction of crystal violet, the rate law is used. The rate law tells us that the rate is equal to a rate constant (k) multiplied by the concentration of crystal violet to the power of its reaction order ([CV+]p) and the concentration of hydroxide to the power of its reaction order ([OH-]q). Rate = k[CV+]p[OH-]q To fully understand the rate law, concentrations of the substances must be looked at first. The concentration is measured in molarity.
Lab: I Scream, We All Scream for …Colligative Properties!? Introduction: When a solute is added to water the physical properties of freezing point and boiling point change. Water normally freezes at 0oC and boils at 100oC. As more solute is added, the freezing point drops (“freezing point depression”) and the boiling point increases (“boiling point elevation”). This property is useful in our lives.
We thought that a pH level of 3 would be the optimal pH level for the enzyme catecholase and its substrate catechol to react in. There was no prior knowledge on the effect of pH levels on catecholase and catechol. The results of the experiment did not confirm this hypothesis; instead the hypothesis was rejected by the results of the experiment. The results showed that tube 1 had the slowest rate of reaction, and actually did not react at all. The results showed that tube 2 had the fastest rate of reaction; this tube was exposed to the neutral pH of 7.
determined results were unsatisfactory to how experiment was supposed to turn out.Part B1. Ran compounds of vanillin and vanillyl alcohol on TLC plates2. Prepared 3 TLC plates 10cm X 3.3cm3. Marked each plate with line 1 cm from bottom then with intervals 1 cm apart on lines for compounds to be spotted.5. Prepared 3 development chambers each with a different solvent.
The salts will be dissolved in distilled water by small quantities until the reaction reaches When ionic compounds dissolve in water, they either absorb energy from or release energy to the surroundings. If a chemical reaction absorbs heat from the surroundings, it is an endothermic reaction. If a solution releases heat to its surroundings, it is an exothermic reaction. The enthalpy of dissolution is the enthalpy change associated with the dissolution of a substance in a solvent at a constant pressure. The change in enthalpy relies on the concentration of the salt solution, because different concentrations will produce different enthalpies.
4. Why are boiling chips useful when boiling liquid? Discussion: In this experiment my partner and I misunderstood how far to carry the significant figures. We took them over two decimals places when it really only should have been one decimal place over. Because we didn’t count the proper number of significant figures in the volume we had too many when we went to calculate the density.
Repeat step nine 11. Make a graph reflecting the timed data 12. Use the changes in the freezing point, recorded mass of the solute and solvent and the freezing point constant for cyclohexane to determine the molecular weight of the unknown substances, both with and without the additions by using the change in freezing point for the organic substance
Experiment 1 Freezing Point Depression of Electrolytes Colligative properties are properties of solutions that depend on the concentrations of the samples and, to a first approximation, do not depend on the chemical nature of the samples. A colligative property is the difference between a property of a solvent in a solution and the same property of the pure solvent: vapor pressure lowering, boiling point elevation, freezing point depression, and osmotic pressure. We are grateful for the freezing point depression of aqueous solutions of ethylene glycol or propylene glycol in the winter and are continually grateful to osmotic pressure for transport of water across membranes. Colligative properties have been used to determine the molecular weights of non-electrolytes. Colligative properties can be described reasonably well by a simple equation for solutions of non-electrolytes.