Sunday
August 31, 2014

Posts by Kamila


Total # Posts: 27

Chemistry
Calculate the average mass, in grams, of an iron atom.
May 5, 2011

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
May 5, 2011

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.
May 5, 2011

Chemistry Help!
An enzyme has one iron atom per molecule and contains .335% iron by mass. Calculate the molar mass of the enzyme
May 5, 2011

Chemistry Help!
In the n = 5 principal shell, what is the maximum number of electrons that can have m1= -2
April 18, 2011

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?
April 18, 2011

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
April 18, 2011

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
April 18, 2011

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?
April 18, 2011

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?
April 5, 2011

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?
March 28, 2011

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?
March 28, 2011

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?
March 28, 2011

Chemistry
What is the energy and wavelength of a photon with a frequency of 91.5 MHz?
March 28, 2011

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?
March 28, 2011

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?
March 28, 2011

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 ...
March 22, 2011

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...
March 21, 2011

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)
March 21, 2011

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?
March 21, 2011

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?
March 21, 2011

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?
March 21, 2011

chemistry
A system delivers 1275 J of heat while the surroundings perform 855 J of work on the system. Calculate ΔU in J.
March 21, 2011

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?
March 21, 2011

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 ...
March 21, 2011

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).
March 21, 2011

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?
March 21, 2011

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