General Chemistry Answers

Convert 0.55 ppm of NO2 to ug/m3 at 217.78C and 100.0 kPa pressure.

please show the steps, formula:

3. How many liters of NO2(g) at STP is released when the following reaction heats 100.0 mL of water by 30.0 oC 3NO2(g) + H2O(l) --> 2HNO3(aq) + NO(g) ∆H = - 138 kJ

4. How many liters of SO2(g) at STP is released when the following reaction heats 250.0 mL of water by 30.0 oC?

2SO2(g) + O2(g) --> 2SO3(g) ∆H = -99.1 kJ

A 5 g of non-volatile piperine, C17H19NO3,is dissolved in 0.5 mol of ethanol, C2H5OH, and 1.4 mol of water, H2O, producing a homogeneous solution. Calculate the vapour pressure of the solution. [Given the vapour pressure of pure ethanol and pure water at 20°C is 43.7 mmHg and 17.5 mmHg, respectively] 

Find the boiling point of a solution containing 45 grams of calcium chloride dissolved in 250 mL of solution.

Calculate the number of grams of bromine (Br₂) needed to react exactly with 50.1 g aluminium (Al). The equation for the reaction is:

2Al (s) + 3Br₂ (l) → 2AlBr₃ (s)

Then, calculate the number of moles of AlBr₃ produced by the process.

Ruthenium-106 has a half-life of 1.0 years. How many half-lives will pass in 25 years?

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14.The frequency of a microwave oven is chosen as it excited the rotational modes of water. These rotational modes then result as heat. How many microwave photons are required to bring 100.0 mL of water boil. Assume all of the photons are absorbed by the water and use an initial temperature of 25.0 oC

please show the steps. formula:

12. Selenium was one of the first elements used in the construction of “electric eyes”, due to its photoconductive properties. The work function for selenium is 5.11 eV. What is the longest wavelength of light that will just cause electrons to be ejected from a surface coated with selenium? (Formally, the electrons leave with no kinetic energy.)

a. In what range of the electromagnetic spectrum does the light of the wavelength from part a fall?

b. When a particular monochromatic light source shines on a selenium surface, photoelectrons are ejected with a kinetic energy of 1.05 eV. What is the wavelength of the incident monochromatic light?

c. Calculate the maximum velocity (m/s) of the ejected electrons from the previous question.

please show steps, formula:

8 a. A photon with enough energy, 5.1 electron volts (eV) of energy, will eject an electron from a piece of gold! What frequency and wavelength do light with this energy have? Note: 1eV = 1.60 ×10-19 J

b. Recalling the information from question 8a, what would happen if you were to shine a light of 6.5 eV on the gold surface? How is this the same or different from using light of 3.0 eV? What if the metal was Cesium (Φ= 2.1eV) or Platinum (Φ= 6.35eV) instead?

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6. A photon of ultraviolet light of 25 nm possesses enough energy to mutate a strand of human DNA. Calculate the:

a. frequency of the light.

b. energy a photon of the light.

c. energy of a mole of photons of the light.

7. The energy required to break double-bonded oxygen in a riboflavin molecule is 23.94 kJ per mole of energy. Assuming light is used to break this bond:

a. What is the wavelength of a photon to break this bond?

b. What is the frequency of the photon?

c. What is the energy of a single photon?