Let's say an average cow emits 100kg of methane per annum.
If coal consists of 80% carbon and 20% moisture and ash, how much
coal would I have to burn per annum to have the same global warming
potential as one cow.
Assume that the carbon in the coal burns completely.
In: Other
5A. Which of the following is true?
A
The thermohaline circulation is partly due to the salinity differences of water.
B
The longer the river, the larger the drainage area.
C
The surface water is much more widely distributed than underground water.
D
None of the above is true.
5B. Plants need moisture to survive. The availability of moisture depends on many factors. Which of the following is true?
A
The more evaporation, the more moisture is available to the plants.
B
The more transpiration, the more moisture is available to the plants.
C
None of the above is true.
5C. The spatial distribution patterns of _ is closely related to _.
A
climate, vegetation
B
fur-bearing animals, climate
C
soil, climate
D
wildfire, soil
5D. Which of the following is true?
A
Winds always have positive effect on life.
B
Wildfires always have negative effect on life.
C
Winds and wildfires always have negative effect on life.
D
None of the above is true.
In: Other
HEAT TRANSFER: HEAT EXCHANGER
Oil flows in a heat exchanger with a mass flow rate of 20 kg/s and is to be cooled from 175 to 65°C with water as a coolant flowing at a rate of 30 kg/s and an inlet temperature of 12°C. The overall heat transfer coefficient is U = 1250 W/m2⋅K.
a) Sketch the temperature profile and calculate the mean temperature for parallel flow, counter flow, and cross flow heat exchangers..
b) Determine the area required to sustain the heat transfer for each heat exchanger stated in (a) Comment on your answer.
c) If fouling with thickness of 2 mm happens on the tubes side, determine the new heat transfer coefficient and evaluate the effectiveness of a 45 m length counter flow heat exchanger before and after fouling. Specific heat capacity of oil and water is given as cp, oil = 2058 J/kg⋅K and cp, water = 4184 J/kg⋅K. Conductivity of fouling is taken as kf,I = 11 W/m⋅K.
In: Other
A 12-cm tall, 6-cm outer diameter cylindrical ceramic mug filled with tea is boiling in a microwave oven. Assume latent heat of evaporation as 2260 kJ/kg. The convection heat transfer coefficient is h=20 W/(m 2 K) and the air in the microwave is at 20 °C. The mug’s wall thickness is 6 mm and the ceramic thermal conductivity is 30 W/(mK). Neglect heat transfer from the bottom of the mug and calculate the rate (in g/s) at which the tea is boiling if the microwave power absorbed by the tea is 50 W.
In: Other
1. A scientific hypothesis is a method in science where
scientists are in the process of trying to prove or disprove a
phenomenon.
a. True
b. False
2. What energy source is Earth using primarily for its
internal processes?
a. Ancient asteroid impact
b. The core
c. Radioactive decay
d. The Sun
3. The element most abundant in Earth's core
is:
a. Calcium
b. Iron
c. Chlorine
d. Silicon
e. Oxygen
4. The asthenosphere is defined as a
__________.
a. Rocky layer having a relatively uniform chemical
composition.
b. Rigid layer of crustal and mantle material.
c. Rocky layer composed mainly of crustal rocks.
d. Plastic layer composed mainly of mantle material.
e. Tsunami zone
5. The least dense layer of Earth is the
__________.
a. Crust
b. Inner core
c. Outer core
d. Mantle
e. Low velocity zone
6. The layer that sits directly under the outer core is
called:
a. Lithosphere
b. Mantle
c. Asthenosphere
d. Inner core
e. Mesosphere
7. The youngest rocks of the seafloor are found at the
mid-ocean ridges of the world.
a. True
b. False
8. What type of plate boundary is located at the
mid-Atlantic Ridge?
a. Divergent boundary
b. Convergent boundary
c. Transform boundary
d. There is no plate boundary
9. What type of plate boundary does the San Francisco
Bay Area sit on?
a. Divergent boundary
b. Convergent boundary
c. Transform boundary
d. There is no plate boundary
10. What type of plate boundary is found off the coast
of Northernmost California, Oregon and Washington
State?
a. Divergent boundary
b. Convergent boundary
c. Transform boundary
d. There is no plate boundary
In: Other
4. We have called plate tectonics a scientific revolution. What other scientific revolutions do you know about? How is the plate tectonics revolution similar to, or different from, other revolutions, such as the Copernican revolution in astronomy? 5. What is the tectonic environment of the place where you live or attend school? Do you live near a plate margin? If so, what type is it? Or do you live in the middle of a plate? If so, which one?
In: Other
Steam at 400°F flows through a 2-in (ID) copper pipe having a thickness of 0.25 in. The outside surface of the pipe is insulated with 1-in-thick layer of fiberglass and 0.008-in-thick layer of aluminum. The outside surface of the insulation is exposed to air at 80°F. The convection coefficients for steam and air are 25 and 12 Btu/h-ft2 -°F, respectively. The thermal conductivity of fiberglass is 0.022 Btu/h-ft-°F. Conductivities of metals may be taken from Geankoplis. a. Calculate the rate of heat transfer for 30-ft length of the pipe in Btu/h. b. What are the interface and surface temperatures? c. Calculate the overall heat-transfer coefficient based on the outside pipe area
In: Other
1) Use the table below to answer the questions that follow.
Thermodynamic Quantities for Selected Substances at 298.15 K (25 °C) __
Substance ΔH ° f (kJ/mol) ΔG ° f (kJ/mol) S (J/K-mol)
Calcium
Ca (s) 0 0 41.4
CaCl 2 (s) -795.8 -748.1 104.6
Ca 2 + (aq) 226.7 209.2 200.8
Chlorine
Cl 2 (g) 0 0 222.96
Cl- (aq) -167.2 -131.2 56.5
Oxygen
O 2 (g) 0 0 205.0
H 2O (l) -285.83 -237.13 69.91
Phosphorus
P 2 (g) 144.3 103.7 218.1
PCl 3 (g) -288.1 -269.6 311.7
POCl 3 (g) -542.2 -502.5 325
Sulfur
S (s, rhombic) 0 0 31.88
SO 2(g) -269.9 -300.4 248.5
SO 3(g) -395.2 -370.4 256.2
The value of ΔH° for the oxidation of solid elemental sulfur to gaseous sulfur dioxide,
S (s, rhombic) + O 2 (g) → SO 2 (g) is __________ kJ/mol.
a) +0.00
b) +11.6
c) +269.9
d) -11.6
e) -269.9
2) Use the table below to answer the questions that
follow.
Thermodynamic Quantities for Selected Substances at 298.15 K (25
°C)
__
Substance ΔH ° f (kJ/mol) ΔG
° f (kJ/mol) S (J/K-mol)
Calcium
Ca (s) 0 0 41.4
CaCl 2 (s) -795.8 -748.1 104.6
Ca 2+ (aq) 226.7 209.2 200.8
Chlorine
Cl 2 (g) 0 0 222.96
Cl- (aq) -167.2 -131.2 56.5
Oxygen
O 2 (g) 0 0 205.0
H 2O (l) -285.83 -237.13 69.91
Phosphorus
P 2 (g) 144.3 103.7 218.1
PCl 3 (g) -288.1 -269.6 311.7
POCl 3 (g) -542.2 -502.5 325
Sulfur
S (s, rhombic) 0 0 31.88
SO 2(g) -269.9 -300.4 248.5
SO 3(g) -395.2 -370.4 256.2
The value of ΔG° at 25 °C for the oxidation of solid elemental
sulfur to gaseous sulfur trioxide,
2S (s, rhombic) + 3O 2 (g) → 2SO 3
(g)
is __________ kJ/mol.
In: Other
Hypothesis: Traffic congestion around the school will affect the air quality and will cause air pollution, and increase noise pollution.
* Can you write an essay (paragraph) about someone you interviewed to prove the hypothesis?
In: Other
I have a report about cold process soap and my doctor want answers of these qusestions...
outcomes:
1. some technical skills in cold process soap.?
2. Work ethics and values in cold process of soap?
3. Employee responsibilities at work?
4. Causes and consequences of workplace accidents.?
In: Other
1. Formaldehyde can be produced by oxidation of C2H4 and the following reaction may occur.
C2H4 + ½ O2 C2H4O C2H4 + 3O2 2CO2 + 2H2O
Using molecular balance method. Equimolar quantity of C2H4 and O2 was used and the product gas analysis shows 28.57% C2H4O, 11.43% CO2, 11.43% H2O, 22.86% C2H4 and 25.71 % O2. Calculate the % conversion of C2H4 and % Yield of C2H4O.
In: Other
In: Other
Example 2.7 Gas Phase Reaction
Gas phase reaction is taking place in a continuous reactor.
Stoicliioinetric proportions of
CO2 and H2 are fed to tile reactor at +00o C. The
reaction proceeds to 80'a completion.
Given I mol of carbon dioxide, estimate the I)eat tllat dust be
provided or removed, if tile
gas exit steams are to be kept at 500'C. Perform the energy balance
using tile lleat of
reaction method at two reference teniperatuies (500'C and 25'C) and
the beat of
formation method
In: Other
Question 1
A) Describe the biogeochemical cycle of carbon as it moves into and through organisms and back to the environment. What are the major human impacts on the carbon cycle? What is so important and significant about these impacts?
B) Describe the predator-prey relationship between the moose and wolves of Isle Royale. How are they linked? What other factors influence these two populations?
In: Other