A chemist titrates 80.0mL of a 0.6050M trimethylamine CH33N solution with 0.2965M HNO3 solution at 25°C . Calculate the pH at equivalence. The pKb of trimethylamine is 4.19 . Round your answer to 2 decimal places. Note for advanced students: you may assume the total volume of the solution equals the initial volume plus the volume of HNO3 solution added.

Background: A 102.4 mL sample of 0.110 M methylamine (CH3NH2, Kb=3.7×10−4) is titrated with 0.230 M HNO3. Calculate the pH after the addition of each of the following volumes of acid.

A.) 0.0 mL

B.) 24.5 mL

C.) 49.0 mL

D.) 73.5 mL

. . Ammonium carbamate (molar mass = 78.08 g/mol) decomposes according to the reaction shown below, producing ammonia and carbon dioxide. (NH4)(NH2CO2)(s) ⇌ 2NH3(g) + CO2(g) Kp = 0.400 at 298 K 10.2 g of ammonium carbamate is sealed in an empty 2.00-L vessel and allowed to come to equilibrium at 298 K.

a. What are the partial pressures of NH3 and CO2 at equilibrium? NH3:_______________________________ CO2:_______________________________

b. What mass of solid ammonium carbamate is in the flask at equilibrium? Answer:_______________________________

c. The temperature of the reaction vessel increased to 398 K; when equilibrium is re-established, the total pressure in the vessel is 4.22 atm. Calculate the values of Kp and Kc at this temperature. Kp:_______________________________ Kc:_______________________________

of the metal ions tested, sodium produces the brightest and most persistent color in the flame. do you think potassium could be detected visually in the presence of sodium by burning this mixture in a flame? could you detect both with a spectroscope?

An electric stove burner on its highest setting exhibits an orange glow.

A) When the burner setting is changed to low, the burner continues to produce heat but the orange glow disappears. How can this observation be explained with reference to one of the fundamental observations that led to the notion of the quanta?

B) Suppose that the energy provided to the burner could be increased beyond the highest setting of the stove. What would we expect to observe with regard to visible light emitted by the burner?

Why do line spectra for substances differ? Could line spectra be used to fingerprint emissions?

A mixture of water and graphite is heated to 600 K . When the system comes to equilibrium it contains 0.11 mol of H 2 , 0.11 mol of CO , 0.31 mol of H 2 O , and some graphite. Some O 2 is added to the system and a spark is applied so that the H 2 reacts completely with the O 2 . Find the amount of CO in the flask when the system returns to equilibrium.

what is the concentration of Cd2+ in a 0.010 M Cd(NO3)2 solution that is also 1.0 M NH3? For Cd(NH3)4^2+, Kf=1.0x10^7

1. If we use symbol U_sys to represent the energy (also referred as internal energy) contained in the system, what is a reasonable symbol to represent the energy of the surroundings? Provide an expression relating the total energy of the Universe, U_univ to the energy of the system and energy of the surroundings? Explain your answer

2. Now consider the system undergoes a process, let DU_sys represent the change in system’s energy, DU_univ represents the change in energy of the universe. Provide an expression for DU_univ in terms of energy change of the system and the surrounding. Explain your answer.

3. Consider your answer in (2), what would be the reasonable sign for DU_univ? Explain.

4. Consider your answer in (2), what would be the reasonable sign for DU_sys? Explain

5. Let q and w represent two ways to exchange energy between system and surrounding. What is a reasonable expression that relates the internal energy change DU_sys with q and w?

6. Consider burning of propane gas (propane and oxygen gases are our interested system), is this an exothermic reaction? What is the sign of q? what is the sign of DU_sys ? Describe in your own words what happened to the internal energy of the system?

7. Identify each energy exchange as heat or work and determine the sign of heat or work is positive or negative

(a) An ice cube melts and cools the surrounding beverages (ice cube is the system here)

(b) A metal cylinder is rolled up a ramp (the metal cylinder is the system)

(c) Steam condenses on skin causing a burn (the condensing steam is the system)

8. Consider a closed container that contains some hydrogen gas (H₂) and oxygen gas (O₂). These gases reacted (burned) and formed water vapor.

(a) Write a balanced chemical equation to represent this process (reaction)

(b) Do you expect this is an exothermic or endothermic reaction? What is the sign of q?

(c)What is the sign of internal energy change DU for this reaction?

(d) List the types of energy stored in the system before and after reactions. How do you explain the sign of internal energy DU observed in part (c)?

Consider the formation of solid Ba(IO 3 ) 2 from the mixing of 7.5mg of barium chloride being dissolved in 500ml of 0.023M sodium iodate.

a) How much solid barium iodate form

b) What is the concentration of barium ions and iodate ions at equilibrium?

How do you would prepare a 2.00 M solution of sodium chloride?

What is the net charge of the dipeptide Glu-Ala at pH=4.1, given the following data for the individual amino acids:

Glu: pKa1= 2.1; pKa2= 9.5; pKaR= 4.1
Ala: pKa1 = 2.3; pKa2 = 9.9