Microwaves can cause tissue damage. For a microwave, emitting energy, wavelength = 12cm, how many photons must be absorbed to raise the temperature of a human eyeball 3 C? Mass of the eye =11g, specific heat of the eyeball is 4.0 J/g K.
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1. Using average atomic masses calculate the number of atoms present in each of the following samples.
(a) 1.27 g of silver, Ag
(b) 0.0010 mol of copper, Cu
(c) 0.0010 g of copper, Cu
(d) 1.76 kg of magnesium, Mg
(e) 2.45 oz of calcium, Ca
(f) 2.45 g of calcium, Ca
(g) 2.45 mol of calcium, Ca
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when salt crystal is dropped into water , how do the molecular properties of water and the ionic properties of salt interact.
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What is the rate constant for a reaction based on the following experimental information?
| Experiment | Rate (M/s) | [A] (M) | [B] (M) | [C] (M) |
| 1 | 0.3126 | 0.25 | 0.53 | 0.45 |
| 2 | 0.3126 | 0.55 | 0.53 | 0.45 |
| 3 | 0.574 | 0.25 | 0.954 | 0.45 |
| 4 | 2.3217 | 0.55 | 1.484 | 1.17 |
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1) The power company is considering installing a new plant using natural gas as fuel to generate the same amount of energy. If the natural gas to be used has an energy capacity of 43MJ/m3 (mega joules per cubic meter of gas)
a) Estimate the volume of natural gas needed in m3/yr.
b) Calculate the annual emissions of criteria pollutants including SO2, NOx, PM and green house gasses including CO2 and CO using the appropriate emission factors given in the table below.
2) Given the cost of Bituminous coal is $750/MT and natural gas is $25/m3 calculate the operating costs for the plant per year.
3) Based on the emission estimates and costs which fuel would you recommend as the best fossil fuel power source for the plant? Why?
| Pollutant | Anthracite coal | Bituminous coal | Fuel oil | Natural Gas |
| CO2 (g/GJ) | 94600 | 101000 | 77400 | 56100 |
| SO2 (g/GJ) | 765 | 1361 | 1350 | 0.68 |
| NOx (g/GJ) | 292 | 183 | 195 | 93.3 |
| CO (g/GJ) | 89.1 | 89.1 | 15.7 | 14.5 |
| Particulate matter (g/GJ) | 1203 | 3254 | 16 | 0.1 |
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A 32.70-g sample of a solid is placed in a flask. Toluene, in which the solid is insoluble, is added to the flask so that the total volume of solid and liquid together is 49.00 mL . The solid and toluene together weigh 58.54 g . The density of toluene at the temperature of the experiment is 0.864 g/mL. What is the density of the solid?
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8. Which of the following species have a zero reading for dipole moment? Give brief reasons for your answers, dealing with each species separately. a. BrF3 b. CH2F2 c. CO d. CO2 e. OF2 f. XeF4
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What fraction of piperazine (perhydro-1,4-diazine) is in each of its three forms (H2A, HA–, A2–) at pH 6.67? The acid dissociation constant values for piperazine are Ka1 = 4.65×10–6 and Ka2 = 1.86×10–10.
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A solution of HNO3 is standardized by reaction with pure sodium carbonate.
2H+ + Na2CO3 --> 2Na+ + H2O + CO2
A volume of 27.87 ± 0.06 mL of HNO3 solution was required for complete reaction with 0.8538 ± 0.0008 g of Na2CO3, (FM 105.988 ± 0.001). Find the molarity of the HNO3 and its absolute uncertainty. Express the absolute uncertainty with three significant figures.
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Gallium (Ga) consists of two naturally occurring isotopes with masses of 68.926 and 70.925 amu. (a) How many protons and neutrons are in the nucleus of each isotope? Write the complete atomic symbol for each, showing the atomic number and mass number. (b) The average atomic mass of Ga is 69.72 amu. Calculate the abundance of each isotope.
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A mixture initially contains A, B, and C in the following concentrations: [A] = 0.450 M , [B] = 0.600 M , and [C] = 0.350 M . The following reaction occurs and equilibrium is established:
A+2B⇌C
At equilibrium, [A] = 0.290 M and [C] = 0.510 M . Calculate the value of the equilibrium constant, Kc.
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What is the pH change of a 0.300 M solution of citric acid (pKa=4.77) if citrate is added to a concentration of 0.150 M with no change in volume?
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Temperature and Observations for Heating Curve.
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Questions
C. Describe the key characteristics for the three states of matter.
D. Define the melting point. What was the observed melting point of water?
E. Define boiling point. What was the observed boiling point of water?
F. What happens to heat energy when it is not increasing the temperature of the substance in the beaker? Use your heating curve to explain your answer.
G. Was temperature perfectly constant during your test while the water was melting and while it was boiling? Explain why or why not. H. The published melting point of H2O is 0°C, and the published boiling point is 100°C. Why may you have found different values?
I. Use the following information to determine if the intermolecular forces of isopropyl alcohol are greater or weaker than the intermolecular forces of water. Explain your answer. The melting point of isopropyl alcohol (rubbing alcohol, C3H8O) is about -90°C and the boiling point is about 82°C.
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The Haber-Bosch process is a very important industrial process. In the Haber-Bosch process, hydrogen gas reacts with nitrogen gas to produce ammonia according to the equation
3H2(g)+N2(g)→2NH3(g)
The ammonia produced in the Haber-Bosch process has a wide range of uses, from fertilizer to pharmaceuticals. However, the production of ammonia is difficult, resulting in lower yields than those predicted from the chemical equation.
1.14 g H2 is allowed to react with 10.1 g N2, producing 1.47 gNH3.
Part A
What is the theoretical yield in grams for this reaction under the given conditions?
Express your answer to three significant figures and include the appropriate units.
Part B
What is the percent yield for this reaction under the given conditions?
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3) What is Rayleigh scattering? Given an excitation wavelength of 350 nm and an aqueous solution, at what wavelengths would you expect to see the Rayleigh scattering peaks in the emission spectrum?
4. Why are anti-Stokes shifts the least common phenomenon compared to Stokes or Rayleigh scattering?
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