Friday
April 18, 2014

Posts by Kamila


Total # Posts: 27

Chemistry
Calculate the average mass, in grams, of an iron atom.

Chemistry
If 200 g. of an unknown metal oxide, M2O3, upon reaction with chlorine yields 376 g of M2Cl2, then the metal M is: a. Indium b. Aluminum c. Gallium d. Silicon e. boron

Chemistry
A solution of sulfuric acid is 50.0% H2SO4 by mass and has a density of 1.15 g/mL. Calculate the molarity of the solution.

Chemistry Help!
An enzyme has one iron atom per molecule and contains .335% iron by mass. Calculate the molar mass of the enzyme

Chemistry Help!
In the n = 5 principal shell, what is the maximum number of electrons that can have m1= -2

Chemistry Help!
The nitrogen-to-hydrogen single bond energy is 389 kJ/mol in NH3. What is the minimum frequency of radiation having the necessary energy to break this bond?

Chemistry
A hydrogen atom electron in an excited state with n = 7 drops to a lower energy state with n = 3. What is the wavelength of the light emitted in this transition

Chemistry
Determine whether the following reaction is endothermic or exothermic: Mg(g) + 2 F (g)--> Mg 2+(g) + 2 F- Mg: I1= 738 kJ/mol I2= 1451 kJ/mol F: EA= -328 kJ/mol

Chemistry
A valence election in an atom of sulfur is excited by heating a sample. The electron jumps from the s orbital to the p orbital. What is the electron configuration of the excited sulfur atom, and what would the orbital diagram look like?

Chemistry
In a hydrogen atom, from what energy level must an electron fall to the n=3 level to give a line at 1.28 um (micrometers) in the infrared region?

Chemistry
In a hydrogen atom, form what energy level must an electron fall to the n=3 level to give a line at 1.28 micrometers (um) in the infrared region?

Chemistry
When light having a wavelength of 497 nm strikes a metal coating of an emitter, an elector with kinetic energy of 2.52 x 10^-19 is ejected. What is the threshold frequency for this metal?

Chemistry
A laser produced a light of wavelenth 575 nm. How many photons of this light would have to strike a material for the material to absorb 55.1 kJ?

Chemistry
What is the energy and wavelength of a photon with a frequency of 91.5 MHz?

Chemistry
Sodium vapor lamps, used for public lighting, emit yellow light of wavelength 589 nm. How much energy is emitted by 5.00 mg of sodium atom emitting light at this wavelength?

Chemistry
The distance between the first and fourth crest of water is 10.9 m. A crest appears every 0.435 minutes, at a point along the wave. What is the speed (m/s) of the water waves?

chemistry
A sample of benzoic acid weighting 1.567 g was burned in a calorimeter. If the initial temperature was 22 degrees Celsius,the final temperature was 31.1 degrees celsius, and the heat capacity of the calorimeter was 4.88 kJ/ degrees Celsius, what is the heat of combustion of be...

chemistry
The ΔH for the solution process when solid sodium hydroxide dissolves in water is 44.4 kJ/mol. When a 13.9 g sample of NaOH dissolves in 250.0 g of water in a coffee-cup calorimeter, the temperature increases from 23.0°C to ________°C. Assume that the solution has...

chemistry
A container holds 1.00 mol O2, and the pressure in the container is 2.00 atm. A student adds 60.0 g of gas Y to the container. The total pressure (of O2 and gas Y) is 3.00 atm. What is the molar mass of gas Y? (V and T constant)

chemistry
The root mean square speed of CH4 at 160 K is 5.0x102 m/s. At what temperature will the root mean square speed of C2H6 be the same?

chemistry
In a certain process, the internal energy of a system increases 40.7 J and the quantity of work the system does on the surroundings is 78.9 J. What is q?

chemistry
Consider the reaction: CH4(g) + 2 O2(g) → CO2(g) + 2 H2O(l) ΔH = - 890.3 kJ What volume of CH4(g) at 25°C and 755 Torr will produce 88600 kJ of heat when reacted with excess oxygen?

chemistry
A system delivers 1275 J of heat while the surroundings perform 855 J of work on the system. Calculate ΔU in J.

chemistry
A gas mixture, has a total pressure of 300. Torr and consists of equal masses of Ne and Ar. What is the partial pressure of Ar, in Torr?

chemistry
A gas bulb is connected to an open end manometer. The pressure in the bulb is 0.355 Torr more than atmospheric pressure. If the manometer is filled with mineral oil (density = 0.888 g/cm3), what will be the difference in height between the two sides of the manometer? Density o...

chemistry
A 0.167 g sample of Mg(s) is burned in a bomb calorimeter which has a heat capacity of 3081 J/°C. In this process, the temperature of the calorimeter increased by 1.34 °C. Calculate the heat given off by burning Mg(s) under these conditions (in kJ/mol).

chemistry
In a Styrofoam cup calorimeter, what is the final temperature when 100. g of iron at 100. ° C is added to 100. g of water at 20. ° C?

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