1. For the demo experiment, the balanced chemical equation is as follows: (NH4)2Cr2O7(s)=Cr2O3(s)+N2(g)+4H2O(g). After the lightning of Ammonium dichromate, Chromium (III) oxide was formed while the Nitrogen and Water escaped into the atmosphere in a gaseous phase. Ammonium dichromate((NH4)2Cr2O7) gave rise to Chromium (III) oxide (Cr2O3), Nitrogen Gas(N2) and water (H2O) In terms of microscopic level, the ratio between reactants and products is as follows. One mole of Ammonium dichromate will give rise to one mole of 1 mole of Chromium (III) oxide and 1 mole of Nitrogen gas and 4 moles of Water is gaseous phase.
Introduction: Freezing point depression is a colligative property that calculates the decrease of the freezing point when any solute is added to a solvent. When determining changes in freezing point, solute concentration is measured in molality which is moles of solute per kilogram of solvent. The concentration unit moles per kilogram is temperature independent, because mass does not vary with temperature. The decrease in freezing point of the pure solvent is proportional to the molality of the particles of solute and is represented by the following equation: ΔTf=Kf ۰ m. By finding the freezing point of an unknown solution, it provides an opportunity to determine the molar mass of the unknown substance. Also, in this experiment a heating
In reactions, this law says that the mass of the original substance is the same after going through a reaction. This is shown with balanced chemical equations. It is needed so that the mass of the product is equivalent to the mass of the reactants. Mole ratio is the ratio of moles of one substance to the moles of another substance in a balanced equation. Mole ratio is considered a conversion factor since it helps to convert units with the use of moles.
The results were graphed to create an absorbance versus molar concentration calibration curve. Finally, the UV absorption of the soda sample was measured and compared to the caffeine standard calibration curve. This was used to calculate the concentration of caffeine. Results
C is plotted and fitted to a logarithmic-line to illustrate the saturation effect, shown in Figure 1. Then using equation 12.8 in the lab manual, C/Y is calculated and plotted versus C and fitted to a straight line, shown in Figure 2. From the fitted line, Ymax, which is the maximum number of moles of acetic acid that can be adsorbed on the surface of the charcoal per gram of charcoal, can be calculated from the slope. Then, using Ymax and the value of the y-intercept, K, which is the ratio between the rate constant k1 of the forward reaction (adsorption on the charcoal) and the rate constant k-1 (detachment from the charcoal), can be determined. For calculations, refer to Appendix E. Finally, multiplying Ymax by Avagadro’s number will give the number of AA molecules adsorbed on the surface of one gram of charcoal at saturation.
Using the combined gas law, the calculated volume of the gas at STP would be 0.0377 liters. If one wanted to find the volume of mole this gas at STP, then all that is required is to divide the 0.0377 liters at STP by the original number of moles of magnesium from the start of the experiment; this would yield the results at STP if one mole of magnesium was reacted, which is the same as one mole of hydrogen produced according to the chemical equation. In the end, the volume of mole of the hydrogen gas produced in this experiment would be equal to 23.6
It is presented as qsoln-q cal. Calorimeter heat change is equal to temperature change multiplied by the calorimeter heat capacity (Ccal). Experiments two and three both have negative heat neutralization for part 2 (NaOH and HCL) and (Mg and HCl), thus the temperature increases as the reaction moves from initial to final
P(B)∙P(A│B)= P(A)∙P(B|A) As a next step both sides are divided by P(B). This results in the following equation: P(A│B)= (P(A)∙P(B|A))/(P(B)) This is the formula of Bayes Theorem, stating the probability of event A given event B happens is equal to the probability of event A multiplied by the probability of event B given event A has happened, all divided by the probability of event
We concluded that the rate of hydrolysis of (CH3)3CCl is directly proportional to water content in the solvent mixture. Aims of experiment • Determine the rate constants for hydrolysis of (CH3)3CCl in solvent mixtures of different composition (50/50 V/V isopropanol/water and 40/60 V/V isopropanol/water) • Examine the effect of solvent mixture composition on the rate of hydrolysis of (CH3)3CCl Introduction With t-butyl chloride, (CH3)3CCl, being a tertiary halogenoalkane, it is predicted that (CH3)3CCl reacts with water in a nucleophilic substitution reaction (SN1 mechanism), where Step 1 is the rate-determining step. The reaction proceeds in a manner as shown
Modeling of Contact Angle for a Liquid in Contact with a Rough Surface When a solid is in contact with liquid, the molecular attraction will reduce the energy of the system below that for the two separated surfaces. This is expressed by the Dupré equation Figure-1 2.1 Wenzel Model: The Wenzel model (Robert N. Wenzel 1936) describes the homogeneous wetting regime, as seen in Figure 2, and is defined by the following equation for the contact angle on a rough surface. where is the apparent contact angle which corresponds to the stable equilibrium state (i.e. minimum free energy state for the system). The roughness ratio, r, is a measure of how surface roughness affects a homogeneous surface.