B) permanent dipoles of molecules containing covalent bonds between atoms of very different electronegativities. C) the hydrophobic effect. D) ion pairing between oppositely charged functional groups. Answer: A Page Ref: Section 5 28) The aggregation of nonpolar molecules or groups in water is thermodynamically due to the A) increased entropy of the nonpolar molecules when they associate. B) decreased enthalpy of the system.
It is known that chlorine is more electronegative than bromine, and thus chlorine is more reactive, and less discriminatory as to what it will react with, thus making bromine more “selective”. Another pertinent piece of information to look at would be stability. The stability of a free radical increases as the number of carbon substituents increases. Therefore, primary is the least stable and tertiary is the most stable. Also, the more stable the free radical that is left behind, the weaker its C-H bond strength will be.
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.
The following data were obtained when a sample of barium chloride hydrate was analyzed as described in the Procedure section. Calculate (a) the mass of the hydrate, (b) the mass of water lost during heating, and (c) the percent water in the hydrate. Mass of empty test tube 18.42 g Mass of test tube and hydrate (before heating) 20.75 g Mass of test tube and anhydrous salt (after heating) 20.41 g. Mass of the Hydrate is 2.33g. Loss (H2O) is 0.34g. Percent H2O in Hydrate is equal 0.34/2.33=14.6% 3.
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
This solution was placed in a burette and 18.4 cm3 was required to neutralise 25 cm3 of 0.1 moldm-3 NaOH. Deduce the molecular formula of the acid and hence the value of n. 5. Sodium carbonate exists in hydrated form, Na2CO3.xH2O, in the solid state. 3.5 g of a sodium carbonate sample was dissolved in water and the volume made up to 250 cm3. 25.0 cm3 of this solution was titrated against 0.1 moldm-3 HCl and 24.5 cm3 of the acid were required.
In the first part, five 100 mL flasks of 5 mL ligand solution, 5 mL 2 M sodium acetate, 4 mL 3 M NH2OH, and 1-5 mL Fe2+ solution are diluted with water. The absorption spectrum for varying concentrations of Fe2+ are measured using a spectrophotometer and the data is graphed in Excel. The slope of the line is ε in the Beer-Lambart equation A = εcl. In the second part of the experiment, eleven flasks containing diluted stock solutions of Fe2+ and ligand are mixed with 5 mL 2 M sodium acetate and 4 mL 3 M NH2OH and diluted with water. The absorption spectrum is measured using a spectrophotometer and the data is graphed in Excel.
When enough amount of SDS is dissolved in water, some properties of the bulk solution are significantly changed. For example, the surface tension decreases and the ability of the solution to dissolve hydrocarbons
Also a larger concentration gradient produces a faster diffusion, and smaller molecules diffuse more rapidly than larger molecules. If you imagine a crystal of dye in a beaker of water, the crystal would be the solute because it is the dissolvable substance, and the water is the solvent because it’s what the solute dissolves into and there tends to be more of it, both of these form together to create a solution. If you look at the colour of the water just next to the crystal it would be
Expansion, an increase in the volume of a substance, usually due to the addition of heat to the substance. The heat causes the molecules of the substance to move farther apart, making the substance occupy more space. A loss of heat causes the opposite effect, known as contraction. Although most substances expand when heated, not all expand at the same rate. Aluminum, for example, expands twice as much as iron when both are heated the same amount.