Chemistry - April 2007

2007-04-25 17:18:29 · 1 answers · asked by Anonymous

Determine the theoretical yield of Na2CO3 if 9.54 grams of H2CO3 is reacted with 7.2 grams of Na. Identify the limiting and excess reactants

2007-04-25 16:58:38 · 2 answers · asked by trust2400 3

2007-04-25 16:40:52 · 7 answers · asked by Ashlee A 1

and giant eagle bag that is used to cover the meat.

2007-04-25 16:30:42 · 1 answers · asked by fred j 1

please

2007-04-25 16:26:30 · 1 answers · asked by hamid 1

2007-04-25 16:10:46 · 1 answers · asked by Pari M 2

The combustion of gasoline releases tremendous amounts of heat. It is the work done on the piston that is the main goal of the reaction, so systems are developed to remove the excess heat produced, since only about 30% of the energy from gasoline is used as work.

2 C8H18 (l) + 25 O2 (g) → 16 CO2 (g) + 18 H2O (g) H = –10110 kJ

C)Let's say that the temperature at which your engine parts begin to melt is 3500 °C. Can your engine handle the temperature you calculated in part b.? Explain your answer.

D)Your engine has an elaborate cooling system that allows it to maintain a reasonable temperature by transferring heat to a coolant. One coolant option may be water. Knowing that water has a high specific heat, freezes at 0 °C, and boils at 100 °C, discuss the pros and cons of using water as your coolant.

2007-04-25 16:08:25 · 3 answers · asked by SUKE! 1

The combustion of gasoline releases tremendous amounts of heat. It is the work done on the piston that is the main goal of the reaction, so systems are developed to remove the excess heat produced, since only about 30% of the energy from gasoline is used as work.

2 C8H18 (l) + 25 O2 (g) → 16 CO2 (g) + 18 H2O (g) H = –10110 kJ

A)Calculate the energy in kJ that is released as heat (70%) by exactly 1 gallon of gasoline. The density of octane is 0.702 g/mL. We will assume for now that gasoline is pure octane. (1 gallon = 3.7854 L)

B)Most of the heat calculated in part a. goes right out the exhaust system and into the air. About 25% of the heat gets absorbed into the metal parts that make up your engine. Let's approximate that the mass of your engine is 79.8 lbs with a uniform specific heat of near 0.43 J/g x °C. If your engine begins at 25 °C, how hot will your engine be if it continuously burns 5.5 gallons of gasoline (octane) while driving? (1 lb = 0.4536 kg)

2007-04-25 16:07:31 · 2 answers · asked by SUKE! 1

Substance - WATER
Specific Latent Heat of Fusion (kJ/mol) - 6.02
Melting Pt (°C) - 0
Specific Latent Heat of Vaporization (kJ/mol) - 40.69
Boiling Pt (°C) - 100

Substance (s) J/g x °C
Water 4.18
Ice 2.09
Steam 2.01

A pot sits on a stove and holds 3.00 L of ice at –35 °C. The stove is turned on and begins to release heat at a steady rate to the pan of ice. Using the above info, calculate the following:

Mass of ice (density of 0.917 g/mL)
Moles of ice in pot
Amount of heat required to change the ice to 0.0 °C
A of H reqrd to liquefy ice at 0.0 °C
A of H reqrd to raise the temp of the water to 100 °C
A of H reqrd to vaporize water at 100 °C
A of H reqrd to raise the temp of the vapor to 130 °C
Total heat reqd to change the ice from its initial to 130 °C

The pot absorbs heat from the stove. Air molecules dissipate some of it before its transferred to the water. Will the heating process take more or less energy?

2007-04-25 16:01:04 · 2 answers · asked by SUKE! 1

1. what will cause a reaction to stop producing more prodeucts?
2. what is the ratio of moles to volume under standard conditionS? you ned only one elaboration

2007-04-25 16:00:38 · 1 answers · asked by ?-? 1

2007-04-25 15:53:24 · 2 answers · asked by Heavy Metal 3

For 1.4 mole of the radioactive isotope molybdenum-99, half-life = 67 hours, how many disintegrations have occurred after 11 minutes

2007-04-25 15:49:03 · 2 answers · asked by Anonymous

How long will it take for 99.9% of a 0.00370 mg sample of radioactive phosphorus-32 to decay? The half-life of phosphorus-32 is 14.30 days, so give your answer in days

2007-04-25 15:42:03 · 1 answers · asked by Anonymous

The half-life of iodine-131 is 8.10 days, so give your answer in days.

2007-04-25 15:33:50 · 1 answers · asked by Anonymous

1. What quantity represents the ratio of the nunmber of moles of solute for a given volume of solution?
2. We dissolve 5.00 grams of sugar, C12 H22 O11, in water to make 1.000 L of solution. What is the concentration of this solution expressed as a molarity?
3. You evaporate all of the water from 100. mL of NaCl solution and obtain 11.3 grams of NaCl. What was the molarity of the NaCl solution?

2007-04-25 15:21:07 · 2 answers · asked by Anonymous

Correct the following volumes of gases for the temperature changes indicated.
5.18L at 76 degress C to 6 degress C

Charles law V2= V1xT2 divided by T1

Volume is liters and Temp in K
V1=5.18
T1= 76 degrees C
T2= 6 degrees C

And 994mL at 27 degrees C to 744 degrees K

2007-04-25 15:19:42 · 3 answers · asked by Natalie F 1

im doing a research project for my chemistry class and I need more information on the molecule "fructose". any help would be greatly appreciated.

2007-04-25 15:18:29 · 2 answers · asked by Anonymous

How long will it take for 75.0% of a 0.00290 mg sample of radioactive chromium-51 to decay? The half-life of chromium-51 is 27.80 days, so give your answer in days.

2007-04-25 15:17:41 · 1 answers · asked by Anonymous

A rock contains 0.688 mg of Pb-206 for every 1.000 mg of U-238 present. Assuming tha tno lead was originally present, that all the Pb-206 formed over the years has remained in the rock, and that the number of nuclides in intermediate stages of decay between U-238 and Pb-206 is negligible, calculate the age of the rock. (For U-238, half life = 4.5 * 10^9 years).

2007-04-25 15:12:19 · 2 answers · asked by coconutty beanz xD 4

2007-04-25 15:09:41 · 2 answers · asked by W 1

Why is the readius of Ca2+ larger than that of Ar?

2007-04-25 15:09:35 · 1 answers · asked by on_gt 1

a gas is enclosed in a cylinder fitted with a piston. the volume of the gas is 2 L at 1 atm pressure. the piston is moved to increase the volume to 6 P. which of the following is a reasonable value for the pressure of the gas at a greater volume and why?

1) 6.00 atm
2) 12 atm
2) .333 atm

2007-04-25 15:02:54 · 2 answers · asked by cbz 1

a certain quantity of a gas occupies 61.3 mL at 68 deg C. if the pressure remains constant, what would the volume of the gas be at 12 deg C?

2007-04-25 15:00:24 · 1 answers · asked by cbz 1

I bought two potato flutes from an open air market in Shanghai; two for 120 yuan. One of the flutes has an eagle either painted or carved in color on it. Is it possible that the paint on the flutes or the flutes contain lead? Is there a test that I can use to find out if they contain lead?

2007-04-25 14:40:40 · 1 answers · asked by mbtafan 3

Match each species below with the correct number of d electrons (n of d^n) for the central metal ion.

1) [RhCl6]3- A. 6
2) Na2[Os(CN)6] B. 4
3) [Mn(CN)6]2- C. 8
4) [Ru(NH3)5Cl]SO4 D. 5
5) Ca[IrF6] E. 3
F. 7

2007-04-25 14:27:15 · 3 answers · asked by thesekeys 3

how many disintegrations have occurred after 11 minutes?

2007-04-25 13:58:40 · 1 answers · asked by Gemini 2

What is the importance of a reversible reaction, irreversible reaction, equilibrium, and Le Chateliers Principle in everyday life and careers? Thanks in advance!

2007-04-25 13:53:33 · 1 answers · asked by lovinlife 1

Many metals occur naturally as sulfide compounds, including CuS and CoS. Air pollution often accompanies the processing of these ores, because toxic sulfur dioxide is released as the ore is converted from the sulfide to the oxide by smelting. Consider the reaction of zinc sulfide with oxygen to form zinc oxide and sulfur dioxide. First write an unbalanced equation for this reaction. Then, how many kilograms of zinc sulfide are reacted when 256 kilograms sulfur dioxide of is processed by this process? How many kilomoles of oxygen are used up?

2007-04-25 13:46:42 · 2 answers · asked by Reed 1

Explain using vapor pressure if possible

2007-04-25 13:42:34 · 1 answers · asked by smokefanTS20 3

Silver chloride us very insoluble in water, and by adding a very slight excess of silver nitrate, it is possible effectively to remove all the chloride ion from the sample. First, write the balanced net ionic equation for this reaction. Then assume that a sample has a mass of 1.054 grams contains 21.5% chloride ion by mass. Then calculate the mass of silver nitrate that be used to completely precipitate all the chloride from the sample?

2007-04-25 13:41:28 · 1 answers · asked by Reed 1