Chapter Two: Freezing Point Depression Measurements Purpose: The purpose of this lab is to measure freezing points and freezing point depression for several solutions. The freezing point depression constant (Kf) for p-xylene was calculated from freezing point measurements and used to estimate the molar masses of three unknown solutes in a p-xylene solution. The end goal of this lab experiment is to correctly identify these three unknown solutes. The molar mass of a solute is able to be determined through freezing point depression measurements because the increase in solutes disrupts crystal formation, requiring a lower temperature to form a lattice. This colligative property is important in many industries, but is clear to see when using ordinary salt to remove ice from steps or a driveway.
Thermal decomposition of carbonates Introduction: Carbonates decompose when they are heated, producing calcium oxide and carbon dioxide. Carbon dioxide can be detected using lime water. Calcium carbonate calcium oxide + carbon dioxide CaCO3 CaO + CO2 Other metal carbonates decompose in the same way. Here are the equations for the thermal decomposition of copper carbonate: copper carbonate copper oxide + carbon dioxide CuCO3 CuO + CO2 Hypothesis: some metal carbonates decompose more easily than others when they are heated. Aim: The times taken for a chemical reaction to take place metals high up in the reactivity series (such as calcium) have carbonates that take a lot of energy to decompose them.
Observation: The temperature of acid and base are the same (room temperature). When start to pouring NaOH into HCl, the temperature increases rapidly. Chemical Equation: NaOH(aq) + HCl(aq) NaCl(aq) + H2O(l) Calculations: (Stapled together, at the back of Data Sheet 2) Results: (Stapled together) Conclusion: We always find the heat of neutralization when we mix acid with base. The heat is the proof for the forming of H2O. We know it exists but we can’t find the way to measure it.
We expect Pentane to be the most ideal because it’s boiling point is the furthest away from the boiling point of water. To test our hypothesis, we used heat to vaporize each gas, an ice bath to cool the gases down and measured the condensed liquid gas to calculate each gas’s constant. Methods: In this experiment, we first measured the mass of an empty flask using
d. Their values get larger as the temperature is increased. e. An order equal to zero means there is no concentration dependence with rate. 2. The gas phase reaction A + B C has a reaction rate which is experimentally observed to follow the relationship rate = k[A]2[B]. The overall order of the reaction a. is first.
The reason for this I concluded, was the collision theory. At the higher molarities of Potassium Iodide there were too many moles and therefore too many collisions were happening. Therefore the product was being made almost instantly. When I reduced the concentration of the reaction this meant there were less particles of iodide in the system so the reaction was happening slower. I also lowered the concentration of Hydrogen Peroxide 0.017M.
The more active the metal the more basic it’s saturated hydroxide solution. The sulfate compounds of alkaline earth metals show decreasing solubilites as you go down a group. This characteristic is used as a means of separating and identifying metallic ions in a group. Carbonates are pretty insoluble. You will observe in this experiment some of the characteristics of the alkaline earth metals discussed here and will write balanced equations for all reactions.
Pseudo first order reactions are used to find the rate constant of a second order reaction when one of your two components is very expensive and the other one is relatively inexpensive. You can use an excess of the inexpensive reagent and use a small amount of the expensive one. The arrhenius equation, k' = A*e(-Ea/R*T), was used to determine the activation energy, where; k = rate A = constant Ea = activation energy R = gas constant T = temperature (kelvin) It was re-arranged to, lnk' = lnA - Ea/RT, in order to find Ea Method Please refer to ‘’DCU School of Chemical Science Second Year Chemistry Laboratory Manual Analytical Science 2012-2013’’ pages 64-67 for experimental procedure. Results See Excel sheets. Calculations M of sodium thiosulphate = 0.4977 0.4977/1000 * 0.45 = 2.2365 * 10-4 moles of Iodine = 2.
Also, the resistance to high temperatures and pressures allow it to go through the metamorphic processes unscathed. Experiment 11 concepts are heavily used in this experiment. The concept of using the MeasureNet Spectrophotometers, analyzing resulting graphs to compare and contrast differing solutions of λ max (or lambda max), therefore comparing and contrasting differing solution wavelengths. Through comparing an “unknown solution” to the known solutions wavelengths, students are able to determine in this particular experiment if chromite is present in the unknown given metal ore sample. If the wavelengths of the unknown metal ore solution share a lambda max or maximum wavelength to the lambda
Introduction Standard heats of formation of chemical compounds are one of the most useful thermodynamic quantities. It is the change of enthalpy that accompanies the formation of one mole of a substance in its standard state from its constituent elements. This is also often used to calculate the heat of combustion, which is the energy released as heat when one mole of a compound undergoes complete combustion with oxygen under standard conditions.  Heat released in a chemical reaction can be determined experimentally by using an adiabatic calorimeter. Calorimetry is the most convenient way to measure the heat of combustion.