Blog

According to collision theory, which condition(s) must be met in order for molecules to react?   1. The reacting molecules that collide with any energy initiate the process of breaking and forming bonds.   2. A catalyst must be in contact with the reacting molecules for a reaction to occur.   3. The reacting molecules must collide with an orientation that can lead to rearrangement of the atoms.

What is the pH of a 0.30 M solution of HCN at 25oC (For HCN, Ka = 4.9 x 10-10)  

Carbon dioxide gas has a Henry’s law constant of 4.48×10-5 M/mmHg at 35.0 °C when dissolving in water. If the pressure of CO2 gas 718 mmHg, what is the concentration of CO2 in the water in mol/L?

What molar ratio of acetic acid to sodium acetate is required to create a buffer solution having a pH of 4.94 at 25°C? Ka for HC2H3O2 is 1.8 × 10–5.

Using the chemical equilibria below,   N2(g) + O2(g)   ⇌  2 NO(g) K1   N2(g) + 3 H2(g)  ⇌   2 NH3(g) K2   H2(g) + 1/2 O2(g)   ⇌  H2O(g) K3 Determine the method used to calculate the equilibrium constant for the reaction shown below.   4 NH3(g) + 5 O2(g)  ⇌   4 NO(g) + 6 H2O(g) Kc  

Calculate the energy in the form of heat (in J) required to convert [x] grams of liquid water at [y]°C to steam at [z]°C. Assume that no energy in the form of heat is transferred to the environment. (Heat of fusion = 333 J/g; heat of vaporization = 2256 J/g; specific heat capacities: liquid water = 4.184 J/g⋅K, steam = 1.92 J/g⋅K; water’s normal melting point is 0°C and normal boiling point is 100°C) (Report your answer in Joules, with 1 decimal place, i.e. xxx.x)  (No units are necessary in answer.)

Calculate ΔrG° at 25.0 °C for the reaction below. 2 Na(s) + 2 H2O() → 2 NaOH(aq) + H2(g) Given: ΔrH° = −366.6 kJ/mol-rxn and ΔrS° = −154.2 J/K⋅mol-rxn.

A 55.0 L gas cylinder contains 60.0 g helium (He) at 13 °C. What is the pressure (in atm) inside the cylinder? (R = 0.08206 L⋅atm/mol⋅K) (Report your answer to 1 decimal place, i.e. x.x) (No units are necessary in answer)

A sample of methane, CH4, occupies a volume of [x] mL at 25°C and exerts a pressure of 1115.0 mmHg. If the volume of the gas is allowed to expand to [y] mL at 298 K, what will be the pressure of the gas (in mmHg)? (Report your answer in mmHg to 1 decimal place, i.e. xxx.x) (No units are necessary in answer.)

A hot piece of iron is dropped into a beaker containing colder water. Which of the following statements is/are CORRECT?1. Energy is transferred as heat from the iron to the water.2. Thermal equilibrium is attained when the iron and the water reach the same temperature.3. The water’s temperature will decrease in this experiment.