Find the pH during the titration of 20.00 mL of 0.2300 M nitrous acid, HNO2 (Ka = 7.1 ✕ 10-4), with 0.2300 M NaOH solution after the following additions of titrant. a) 0mL b)10.00mL c) 15.00mL d) 19.00mL e)19.95 mL f) 20.00mL g) 20.05mL h) 25.00mL

explain the meaning of the activation energy and the pre-exponential factor in the arhenius equation (K=A*exp(-Eact/RT)

A sample of methane (CH4) has a volume of 26 mL at a pressure of 0.85 atm . What is the volume, in milliliters, of the gas at each of the following pressures if there is no change in temperature and amount of gas? 1. 0.35 atm 2. 2.30 atm 3. 3100 mmHg The volume of air in a person's lungs is 626 mL at a pressure of 761 mmHg . Inhalation occurs as the pressure in the lungs drops to 731 mmHg with no change in temperature and amount of gas. 1. To what volume, in milliliters, did the lungs expand? А sample of neon initially has a volume of 3.00 L at 16 ∘C . 1. What is the new temperature, in degrees Celsius, when the volume of the sample is changed at constant pressure and amount of gas to 5.50 L ? 2. What is the new temperature, in degrees Celsius, when the volume of the sample is changed at constant pressure and amount of gas to 1500 mL ? 3. What is the new temperature, in degrees Celsius, when the volume of the sample is changed at constant pressure and amount of gas to 8.50 L ? 4. What is the new temperature, in degrees Celsius, when the volume of the sample is changed at constant pressure and amount of gas to 3700 mL ? A balloon contains 2500 mL of helium gas at 85 ∘C. What is the new volume of the gas when the temperature changes to the following, if n (the amount of gas) and P are not changed? 1. 40 ∘C 2. 660 K 3. -15 ∘C 4. 235 K

A) A 50.0-mL volume of 0.15 M HBr is titrated with 0.25 M KOH. Calculate the pH after the addition of 20.0 mL of KOH.

B) A 75.0-mL volume of 0.200 M NH3 (Kb=1.8×10−5) is titrated with 0.500 M HNO3. Calculate the pH after the addition of 28.0 mL of HNO3.

C) A 52.0-mL volume of 0.35 M CH3COOH (Ka=1.8×10−5) is titrated with 0.40 M NaOH. Calculate the pH after the addition of 15.0 mL of NaOH.

Find the pH at the equivalence point(s) and the volume (mL) of 0.125 M HCl needed to reach the point(s) in titrations of the following. (See this table.) (a) 69.0 mL of 0.225 M NH3 volume to reach equivalence point pH at equivalence point

If the Ka of a monoprotic weak acid is 3.4 × 10-6, what is the pH of a 0.34 M solution of this acid?

32. When the following reaction is balanced what is the coefficient for ^-OH?

____N₂H₄ + ____ClO₃^- + ____^-OH à ____NO₃^- + ____Cl^- + ____H₂O

a.2                b. 4                  c. 6                  d. 8                  e. 10

33. What species is the reducing agent for the reaction above?

            a. N₂H₄            b. ClO₃^-           c. ^–OH             d. NO₃^-                     e. Cl^-

34. When the following reaction is balanced what is the coefficient for NaCl?

____NaClO₃ + ____H₂O + ____I₂ → ____H⁺ + ____IO₃^- + ____NaCl

            a. 1                  b. 2                  c. 3                  d. 4                  e. 5

35. What species is the oxidizing agent for the reaction above?

            a. NaClO₃                                 b. H₂O                         c. I₂                             d. IO₃^-                                           e. NaCl

A 2.00 mole sample of Ar undergoes an isothermal reversible expansion from an initial volume of 2.00 L to a final volume of 85.0 L at 313 K .

a) Calculate the work done in this process using the ideal gas equation of state.

b) Calculate the work done in this process using the van der Waals equation of state.

c) What percentage of the work done by the van der Waals gas arises from the attractive potential?

4- Hydrogen and chlorine gas are placed in a 10.0 L container and allowed to react. The initial density of the mixture is 5.01 x10-3 gm/ml. The vessel is at 300K and the initial pressure is 6.52 atm. After the reaction is complete , the pressure is 6.52 atm. The gas is bubbled into 1.00 liter of deionized water. In another part of the universe, a grey haired chemistry instructor prepares an acetic acid/ acetate buffer. The buffer was prepared by adding acetic acid and sodium acetate to 2.50 L of deionized water. Now, as universes collide, our hero adds 107 ml of the HCl solution to 405 ml of the buffer. The pH is measured and is 4.35 after the HCl addition. A drop of phenolphthalein is added and the solution is titrated to equivalence with 657 ml of 0.920 M NaOH. Calculate the original molarities of the weak acid and conjugate base in the 2.50 L solution?

2- Gases A2 and B2 react according to the equation: A2 + B2 → AxBy . If equimolar ( not necessarily stoichiometrically equivalent) quantities are placed in a reaction vessel with a massless, frictionless piston and allowed to react to completion. The density of the gas mixture after reaction is 1.5X the original density. Find the empirical formula? Is there only one possibility? Explain.

When coal is burned, the sulfur present in coal is converted to sulfur dioxide (SO2), which is responsible for the acid rain phenomenon. S(s) + O2(g) → SO2(g) If 4.82 kg of S are reacted with oxygen, calculate the volume of SO2 gas (in mL) formed at 29°C and 1.16 atm.

. Calculate the mass in grams of hydrogen chloride produced when 5.65 L of molecular hydrogen measured at STP reacts with an excess of molecular chlorine gas.

H2(g) + Cl2(g) → 2HCl(g)

To verify the existence of silver in your solution, one should first form a white precipitate by addition of NaCl. Next, the precipitate should dissolve in aqueous ammonia. Silver can re-precipitate by addition of 6M HNO₃. Using chemical equations, describe the identity of the product formed in each step. (3pts) (Your three steps should be after addition of NaCl, after addition of ammonia and after addition of HNO₃.)

1. Which one describes not about a nuclear reaction but about a chemical reaction?

a.) Estimate the freezing point of 250 mL of water to which 8.5g of magnesium nitrate has been added. treat each solution as ideal.

b.) If we were to use 8.5g of strontium nitrate instead of magnesium nitrate, would the freezing temperature be higher or lower ( or unchanged) compared to solution in part a?

c.) if we were to use 8.5g of aluminum nitrate instead of magnesium nitrate ( as in part a), would the freezing point be hight or lower ( or unchanged) compared to solution in part a?