Reaction rate is affected by any catalysts present (which speed up the reaction usually with an intermediate step), temperature (increases the number of particles collisions), concentration (increases the number of collisions), and surface area (increases the space available for collisions). Reactions can only occur when collisions take place. The most generic form of the rate law is Rate = K * [A]m * [B]n where (k is a constant specific to an equation and temperature). Now, the compounds A and B might not have any effect on the rate, which would cause them to drop out of the equation completely, or they might have so much effect that they are raised an order (squaring the concentration). The rate law for this reaction is k [CV+]m[OH-]n. Since the hydroxide ion concentration at the beginning is about 1000 times larger than the concentration of crystal violet, [OH-] will not change that much during this
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.
Distillation is used to purify a compound by separating it from a non-volatile or less-volatile material. When different compounds in a mixture have different boiling points, they separate into individual components when the mixture is carefully distilled. The boiling point is the temperature at which the vapor pressure of the liquid phase of a compound equals the external pressure acting on the surface of the liquid. The external pressure is usually the atmospheric pressure. Different compounds boil at different temperatures because each has a different, characteristic vapor pressure: compounds with higher vapor pressures will boil at lower temperatures.
Each of these types of reactions behaves in a similar fashion. They all involve the conversion of one substance to another substance, while preserving the original elements in some form. Another aspect of predicting products is the chart of reactivity. In order for the replacement of an element in a compound to happen, the element replacing the original element must be more reactive. The chart of reactivity tells chemists the comparable reactivity of elements.
B) Greenhouse gases prevent heat from leaving the earth. C) If the level of greenhouse gases increases, the temperature will decrease. D) Some greenhouses gases are needed to keep the proper temperature balance. E) none of the above 3) Which of the following is TRUE? A) Stoichiometry allows prediction of the amounts of products that form in a chemical reaction based on the amounts of reactants.
For this particular exercise, you should be familiar with the following: • Sublimation: Many chemicals will sublime (phase change from solid state to gas state) provided the right conditions. Iodine, for example, sublimes at room temperature. A bottle of iodine will thus always have crystals forming around inside the bottle around the cap where sublimed iodine is being deposited (phase change from gas state back to solid state). Provided the proper equipment, chemicals that are being sublimed can be recovered. Decant(ing): Decanting is a way of separating a solid from a liquid.
The collision theory is the theory that molecules have to collide in a certain way with a certain amount of energy in order to react and form a new product; when molecules collide that can react, they need a certain amount of energy (also known as activation energy) in order to break existing bonds and then form new bonds as the new product. Many factors can affect the collisions of the molecules which will in-turn affect the rate of reaction such as temperature, concentration, use of a catalyst and surface area (1, 2). The effects concentration has on the collisions of the molecules will be looked at since this comes into correlation with the experiment at hand; the more concentrated a solution is, means the more molecules there are to collide which will mean a higher rate of reaction if the concentration is being raised and a slower rate of reaction if the concentration is being lowered. Since in this experiment the concentration of sodium thiosulphate will be lowered each time, the effective
However, different molecules will move at quite different and individual rates depending on the physical characteristics of the molecule and on experimental system used. The velocity of movement, ν, of a charged molecule in an electric field depends on variables described by Eq/ f • Nucleic acid molecules are size separated by the aid of an electric field where negatively charged molecules travel toward anode (positive) pole. The migration flow is resulted solely by the molecular weight where small weight molecules migrate faster than larger ones. In addition to size separation, nucleic acid fractionation using agarose gel electrophoresis can be an initial step for further purification of a band of interest. Extension of the technique includes expunging the desired “band” from a stained gel viewed with a UV transilluminator.
Title: Experiment 2.15 – The Stability of the Tri-iodide Ion Abstract: The aim of this experiment was to determine the stability constants for iodine in two solutions which varied in both their volume of Potassium Iodide and the presence or absence of water. To this end two different mixtures of Potassium Iodide were made up and mixed in a mechanical shaker. The solutions were then separated into organic and aqueous layers. 1 cm3 samples of the 4 solutions were then titrated with sodium thiosulphate and using the resulting titrant values, the stability constant determined. The experiment was successful.
Diffusion, Osmosis and Active transport. Diffusion: Seeing that substances have kinetic energy (energy of motion), they are continuously moving around, colliding with one another, and moving in various directions. The random mixing of ions and molecules due to their kinetic energy is called diffusion. If a particular ion or molecule is present in an area where there is a lot of that particular molecule, it would be in a high concentration area of itself. All the molecules would then collide with each other due to their kinetic energy, eventually forcing themselves away from each other, where there is more space.