Chemistry Questions and Answers February 20, 2020

Add sample of NH4NO3(s) to water and measured the temperature over time. The data are shown in the graph above. (a) What is the value of T that the student should use to calculate q ? (b) According to the graph, is the dissolution ofNH4NO3(s) endothermic or exothermic? Explain. (c) Are the strengths of the interactions between the particles in the

25 24 23 22 21 Time Temperature (C)

For HEPES buffer is pH 4.28, THE pKa is 7.55 a. What is the ratio of A-/ HA in the buffer that is present in the solution? b. How many micromoles of A- and HA are present in the solution? c. If you now add 3 ml of 1M NaOH, will you still have a valid buffer? Explain.

An organic complex (HIn) changes its color at a given pH when either its acidic form (color 1) or basic form (color 2) become dominant. The complex has an acid dissociation constant of 4.80 x 10 -6 at ordinary temperatures. The accompanying absorbance data are for 8.00 x 10 -5 M solution of the compound measured in 1.00-cm cells in strongly acidic

Assume three mol H+ must be translocated to synthesize one mol ATP as described in part B above. Given the following steady-state concentrations: ATP = 3.40 mM and Pi = 5.50 mM, the membrane potential = 168 mV (inside negative), and the pH values in part A, calculate the steady-state concentration of ADP at 37C when G = 11.7 kJ/mol. Express your

If the antifreeze is composed of 50% ethylene glycol (HOCH 2 CH 2 OH), what is the molality of a 250mL glycol solution? What will be the freezing and boiling temperature of H2O in the presence of ethylene glycol.

A certain solution was prepared by mixing 25.0g of a nonelectrolyte solute in 75g of H2O. The solution then produced freezes at -10.0C. What is the molar mass of the solute?

"If the average molecular weight of an amino acid is about 110 g/mole, and one molecule of water is used to hydrolyze and one peptide bond, what volume of H 2 O would be needed to hydrolyze a quarter pound of steak to single amino acids? Assume the steak is 100% protein."

Consider the decomposition of N 2 O 5 as shown in the following equation to answer the next three questions: 2 N 2 O 5 (g) 4 NO 2 (g) + O 2 (g) 1. If the rate of decomposition of N 2 O 5 at a particular instant in a reaction vessel is 4.2 x 10 -7 M/s, what is the rate of appearance of NO 2 and O 2 respectively? 2. The reaction shown above has

Many anions are quite stable in the aqueous phase, but not so much in organic solvents where its necessary to perform some reaction (usually nucleophilic substitutions). I have heard that crown ethers are good phase transfer catalysts that bring ions to the organic phase. 18-crown-6 is used to coordinate to K+KX+ ions and bring them to organic

At 25C and 1 atm, a 0.5000molkg solution of Nacl in water has VNa 18.63 cm3mol and VH0 18.062 cm3mol. Find the volume at 25C and 1 atm of a solution prepared by dissolving 0.5000 mol of Nacl in 1000.0 g of water. 3D