Choose all the true statements.

-Liquid water has a lower entropy than liquid benzene at 25°C because of hydrogen bonding in water.

-Entropy is the main driving force in the formation of the DNA double helix.

-All elements in their standard states have an entropy of zero at 25°C.

-Reactions that involve only gases always have a positive change in entropy

-Evaporating a liquid has always a positive change in entropy freezing water is possible only if the entropy of the surroundings increases

-It is impossible to freeze ethanol because the change in entropy of the system is negative.

-Ice at 0°C has a higher entropy than liquid water at 0°C because the density of ice is lower than the density of water.

-Binding a substrate to an enzyme always lowers the entropy because the substrate loses translational and rotational degrees of freedom.

Five moles of TiCl4 are combined with two moles of Ti.

a) How many moles of TiCl3 are produced according to the following reaction?

3TiCl4 + Ti = 4TiCl3

I know the answer for A is 6.7 mols TiCl3.

I know 2 mols of Ti (4 mol TiCl3 / 1 mol Ti) = 8 mol and 5 mols TiCl4 (4 mols TiCl3 / 3 mols TiCl4) = 6.7 mols TiCl3

What I don't understand is where the 5 is coming from. Wouldn't the balanced equation use 6 and not 5?

This is my main question and I would appreciate any detailed replies to help me understand. Thank you.

: A suspension of colloids at room temperature (25°C) contains CaS0₄ in (a) 3 mM and (b) 30 mM concentration. Find the Debye length (in nm) for both the cases. Use relevant data given in lecture 12-13. (c) Why do you suppose the Debye length changes with change in salt concentration? Provide reasoning from colloidal science to support your answer. (d) If NaCI was used instead of CaS0₄, how would the Debye length values change for cases (a) and (b)? (No calculation necessary for part (d))

What is the systematic name of [Os(NH3)2(en)2]Cl3, [Co(NH3)3(en)Cl]NO3, and (NH4)2[Fe(EDTA)]?

1). Two 20.0 mL samples, one 0.200 MKOH and the other 0.200 M CH3NH2, were titrated with 0.100 MHI. Answer each of the following questions regarding these two titrations.

a). What is the volume of added acid at the equivalence point for KOH?

b). What is the volume of added acid at the equivalence point for CH3NH2?

c). Predict whether the pH at the equivalence point for each titration will be acidic, basic, or neutral.

d). Predict which titration curve will have the lowest initial pH.

2). Potassium hydroxide is used to precipitate each of the cations from their respective solution. Determine the minimum concentration of KOH required for precipitation to begin in each case.

a). 1.2×10⁻² M CaCl2

3). Use the Henderson–Hasselbalch equation to calculate the pH of each solution:

a). a solution that contains 1.31% C2H5NH2 by mass and 1.20% C2H5NH3Br by mass

b). a solution that is 11.5 g of HC2H3O2 and 11.5 g of NaC2H3O2 in 150.0 mL of solution

The following rate data was collected for a reaction X + Y -> Products

     Exp.            [X]                         [Y]                Rate of formation of a product

     1                0.23 M                 0.17 M                    0.33 M/h

    2                0.46 M                 0.17 M                    0.66 M/h

    3               0.23 M                0.51 M                    0.99 M/h

a. Determine the orders with respect to the two reactants and write the rate law for the reaction

b. Calculate the value of the rate constant and include the units of the rate constant

16. Does the reaction Cu²⁺ + Mg (s) →    Cu (s) + Mg²⁺ occur spontaneously in aqueous solution?

            A.     yes                      B.    no

17. Does the reaction 2 Al³⁺ + 3 Pb (s) →    2 Al (s) + 3 Pb²⁺ occur spontaneously in aqueous solution?

            A.     yes                      B.    no

Calculate the [H⁺], [OH^-], pH, pOH for the resulting solution if 20.00 mL sample of 0.2650 M NaOH was titrated with 21.33 mL of 0.1175 M H₂SO_4.

19. A. Solid calcium nitrate is slowly added to 175 mL of a 0.0676 M potassium carbonate solution. The concentration of calcium ion required to just initiate precipitation is _____ M.

B. Solid zinc acetate is slowly added to 125 mL of a 0.0515 M potassium cyanide solution. The concentration of zinc ion required to just initiate precipitation is _____ M.

C. Solid sodium hydroxide is slowly added to 150 mL of a 0.0435 M copper(II) acetate solution. The concentration of hydroxide ion required to just initiate precipitation is _____ M.

Caproic acid is composed of C, H, and O atoms. The combustion of a 0.225g sample yields 0.512g of CO2 and 0.209g of H2O. What is the empirical formula for the compound?

A 1.00 L flask is filled with 1.45 g of argon at 25 ∘C. A sample of ethane vapor is added to the same flask until the total pressure is 1.450 atm .

What is the partial pressure of ethane, Pethane, in the flask? Express your answer to three significant figures and include the appropriate units.

Determine the vapor pressure of a solution at 55°C that contains 34.2 g NaCl in 375 mL of water. The vapor pressure of pure water at 55°C is 118.1 torr. The van't Hoff factor for NaCl is 1.9

interrelationship between global warming, acid rain, ozone layer depletion, and photochemical smog?

12.       What is responsible for capillary action, a property of liquids?

a)         surface tension

b)         cohesive forces

c)         adhesive forces

d)         viscosity

e)         two of these

32. Which of the following correctly states the relationship between temperature and the solubility of a substance in water?

a) The solubility of a substance in water increases as the temperature rises, especially for gases. b) The solubility of a substance in water decreases as the temperature rises, especially for ionic solids. c) The solubility of a substance in water with temperature cannot be accurately predicted, especially for ionic solids. d) The solubility of a substance in water decreases as the temperature lowers, especially for gases. e) Both A and D are correct.