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.
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.
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
Title Problem Definitions Hypothesis Background Information Procedure Materials Results Conclusion References and Acknowledgements Reactions with Alka-Seltzer How does the temperature of water effect how fast the chemical reaction of Alka-Seltzer happens? I think the Alka-Seltzer will react faster in very hot water because the molecules are moving around faster. Therefore, they will run into each other faster causing a faster chemical reaction. Molecules: Two or more atoms which have chemically combined to form something Temperature: A measure of warmth or coldness Reaction Rate: The speed of a reaction Reactants: The substance(s) first involved in a chemical reaction Chemical
For part 2, do the same thing as part 1 except use an unknown hydrate and calculate the percent mass of water in an unknown hydrate. Observations Part 1 At first the hydrate was a crystal red color. When it was placed on the hot plate and its state changed it began to change color. As it heated it started to become liquidly and bluish in color. Once it cooled down it became a purplish black color.
(d) What evidence suggests that nitrate compounds are soluble in water? (e) Write the chemical formula for each precipitate that formed. Apply and Extend (f) Write a balanced chemical equation for each precipitation reaction that occurred. (g) Why is it necessary to use distilled water to prepare the solutions used in this investigation? (h) "Hard" water contains a high concentration of calcium ions.
How do we disrupt the hydrological cycle? As the population increases, more water is needed to sustain human life, this leads to us over abstracting water from aquifers and bore holes, this means that there could be a reduction of water underground for future generations, as some aquifers can take 100s of years to replenish. We also pollute water ways with dangerous chemicals from mining and pesticides and herbicides from agriculture which affects underground water storages like bore holes. Poor irrigation practices raise soil salinity and evaporation rates. These factors contribute to a reduction in the availability of portable water, putting even greater pressure on existing water supplies.
25 cm3 of a solution of sodium hydroxide reacts with 15 cm3 of 0.1 mol/dm3 HCl. What is the molar concentration of the sodium hydroxide solution? 4. Succinic acid has the formula (CH2)n(COOH)2 and reacts with dilute sodium hydroxide as follows: (CH2)n(COOH)2 + 2NaOH → (CH2)n(COONa)2 + 2H2O 2.0 g of succinic acid were dissolved in water and the solution made up to 250 cm3. This solution was placed in a burette and 18.4 cm3 was required to neutralise 25 cm3 of 0.1 moldm-3 NaOH.
Gas or its inability to escape is what causes volcanos to become violent. The longer gas is trapped, the more pressure builds up. The cause of gas building up is the result of the viscosity of the magma the gas is trapped in. Viscosity is the measure of the flow or how easily a liquid flows. If a liquid is viscous it is thick and will flow slowly like honey whereas a liquid that is nonviscous will flow like water.
Title Hydrochloric acid and sodium thiosulphate: how reaction rate varies with sodium thiosulphate Concentration Introduction When sodium thiosulphate reacts with hydrochloric acid, sulphur is produced. The sulphur that is produced forms in very small particles and causes the solution to cloud over and turn a yellow colour. This basic word equation sums up the reaction: HCL + sodium thiosulphate sodium chloride + sulphur dioxide + sulphur + water The aim of this experiment is to observe and record the rate of reaction of hydrochloric acid and sodium thiosulphate; a conical flask above a marked 'x' will be filled with the required amounts of hydrochloric acid and sodium thiosulphate and then the amount of time it takes for the reaction to occur and for the marked 'x' to disappear will be measured. The scientific principle in effect here is the collision theory. 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.