Chemistry - November 2007

Gas X is found to be 24% carbon and 76% flourine by mass.
(a) determine the empirical formula of gas X.
(b) if the molar mass of gas X is 200.04 g/mol, determine its molecular formula.

2007-11-29 14:05:38 · 3 answers · asked by Anonymous

Sulfamic acid and sodium nitrtae should not be brought together as solids for safety reasons. Nevertheless, why is water added to the containers containing each of the two solds before mixing them together to form a reaction that results in N2 gas? Is it to better mix the two solutions? or to inhibit the amount of dangerous heat that can be produced when mixed together only as solids?

2007-11-29 14:05:33 · 2 answers · asked by Steve C 1

Which of the following must be true for a molecule to be considered polar? (Select all that are true.)
1.The molecule must not contain polar bonds.
2. It must have a nonzero net dipole moment.
3.The molecule must contain polar bonds.
4.The molecule must be of a geometry in which the dipole moments of the bonds do cancel each other.
5. There must be a significant difference in electronegativities between bonded atoms.
6. It must have a net dipole moment equal to zero.
7. The molecule must be of a geometry in which the dipole moments of the bonds do not cancel each other out.

2007-11-29 14:04:58 · 1 answers · asked by Donna L 3

so i have a final coming up in my chem. lab and i have been stumped on a few of the study material problems... by any chance can you help me with them? try to show your work as much as possible i need to figure out how to do them so i will be able to do them on the final as well. thanks everyone who helps me out with these...

1) A sample of 16.78 mL of 0.103 N H2SO4 is titrated with 0.177 N NaOH.

a) how many mL of NaOH will it take to reach the endpoint?
b) What is the molarity of the H2SO4 solution?
c)How many grams of NaOH will it take to reach the endpoint?

2) What volume will 4.4 grams of CO2 gas occupy over water at 30 derees Celcius and a barometric pressure of 700mm?

I will really appreciate any help offered with the two problems thank you once again!

2007-11-29 13:59:12 · 4 answers · asked by It can only be me! 1

2007-11-29 13:51:41 · 2 answers · asked by dudefjeld 1

Cyclohexanol has a heat of vaporization of 54 kJ/mol and the absolute entropies of the liquid and gas are 200 and 328 J/K-mol, respectively. Which of the following is false?



a. The entropy of vaporization is positive.
b. The heat of formation of liquid cyclohexanol is less than that of the vapour.
c. At 80oC the free energy change for the vaporization is negative.
d. At the boiling point the free energy change for vaporization is zero.
e. At 80oC, cyclohexanol vapour spontaneously condenses into a liquid.



help please

2007-11-29 13:43:46 · 2 answers · asked by Anonymous

This is from a packet that my chem. teacher gave me as homework that is due tommorow. We did a lab on the alkali metals, which react to water. Sodium and Potassium are both alkali metals.

PLEASE HELP!

2007-11-29 13:42:19 · 3 answers · asked by oh.emgeeitzjesska 1

2007-11-29 13:37:45 · 4 answers · asked by khaye 1

2007-11-29 13:37:42 · 1 answers · asked by Oma 1

2007-11-29 13:37:14 · 0 answers · asked by Oma 1

How many moles of oxygen (O2) must be placed in a container with a volume of 50.0 liters to produce a pressure of 4.50 atm at standard temperature? (Points: 1)
32 mol
7.5 mol
10.0 mol
28.0 mol


2. A sample of gas measures 3.50 liters at 273 K. At what temperature will its volume become 4.50 liters, assuming pressure remains constant? (Points: 1)
212 K
173 K
351 K
cannot be determined


3. A 5.0 liter tank of oxygen gas is at a pressure of 3.0 atm. What volume will be available if the oxygen is used at the normal atmospheric pressure of 1.0 atm? (Points: 1)
.6 liters
15.0 liters
1.67 liters
cannot be determined


4. What would happen to the pressure of a sample of gas if it were moved from sea level to 6.0 km above sea level? (Points: 1)
the pressure would stay the same
the pressure would be halved
the pressure would be doubled
the pressure would be tripled


5. R, the gas constant in the ideal gas equation, has a numerical value of 0.0821, what are the units? (Points: 1)
atm-liter/mol-K
atm-m3/mol-K
Pa-m3/mol-K
Pa-liter/mol-K


6. The most useful unit for describing the amount of gas is the: (Points: 1)
liter
cubic meter
mole
atmosphere


7. The temperature scale that has absolute zero as its zero point is the: (Points: 1)
Celsius scale
Kelvin scale
Rankin scale
Fahrenheit scale


8. The characteristics/variables of gases needed to describe a gas completely include all of the following except: (Points: 1)
pressure
temperature
density
volume


9. The ability of gas to spread rapidly through other gases is explained by: (Points: 1)
frequent inelastic collisions of the particles
the high density of gases
the high temperature of gases
constant random motion of particles


10. Collisions of gas particles in which no energy of motion is lost are called: (Points: 1)
perfectly elastic
mostly elastic
both elastic and inelastic
inelastic


11. Raising the temperature of a gas in a fixed volume container will most likely change the: (Points: 1)
number of particles in the container
density of the gas in the container
pressure exerted by the gas in the container
size of the gas particles in the container


12. Which of the following is not a property of gases? (Points: 1)
Gases can be compressed into smaller spaces
Gases diffuse throughout other gases
Gases exert pressure on objects
Gases are weightless near the surface of the Earth


13. Represented by “R” used in the ideal gas equation: (Points: 1)
ion
electronegativity
cathode ray
gas constant


14. What is the density (g / L) of CO2 at 25oC, 1.8 atm ? (R=.0821 L atm / K mol)? (Points: 1)
12.5
3.2
5.9
.088


15. How much faster is He gas than CO2? (Points: 1)
3.3
5.5
11.3
15.4


16. Real gases exist at: (Points: 1)
high temperature, high pressure
low temperature, low pressure
low temperature, high pressure
absolute zero


17. Which of the following is not part of the kinetic molecular theory? (Points: 1)
The higher the pressure of a gas, the higher the speed.
The lower the temperature of a gas the lower the speed.
Attractions between gas molecules are negligible.
The energy between gas molecules collisions are conserved.


18. How many moles of an ideal gas exist at 2.0 atm, 195 L, 25 oC ? (R = .0821 L atm / K mol )? (Points: 1)
2.0
4.0
16.0
32.0


19. Convert 250. ml of a gas at 25 oC, and 845 mm Hg to STP. (Points: 1)
255 mL
355 mL
455 mL
555 mL


20. As the pressure of a gas increases at constant temperature, the volume: (Points: 1)
stays the same
increases
varies up and down
decreases

2007-11-29 13:34:48 · 3 answers · asked by whf 2

2007-11-29 13:33:29 · 1 answers · asked by Anonymous

For testing the water from the ion-exchange resin, you used 1 to 3 ml of water, instead of 5mL of water. How can you directly compare the number of drops needed for permanent suds when you use a different volume of water?

2007-11-29 13:33:01 · 1 answers · asked by snailtrail 1

2007-11-29 13:30:18 · 3 answers · asked by snailtrail 1

2007-11-29 13:28:32 · 3 answers · asked by snailtrail 1

why don't tap water, C2CH5Oh, HC2H3O2, NH4O, and NaCl conduct a lot of electricity?
also, what is an electrolyte?????

2007-11-29 12:59:27 · 5 answers · asked by Anonymous

PLease make the answer simple, not complex in order for me to understand it, thank u! =]
I also have another Q.....
What happens in term of the transfer of energy as heat when you hold a snowball in your hands?

2007-11-29 12:44:35 · 6 answers · asked by Anonymous

2007-11-29 12:06:19 · 2 answers · asked by twee 1

What elements are in these groups?

Transition Metals:

Metals:

Rare Earth Elements:

Lanthanoin Series:

Actinoid Series:

Nonmetals:

Ten points to the first one whose correct!

2007-11-29 11:57:32 · 2 answers · asked by Kriss 2

2007-11-29 11:55:51 · 5 answers · asked by Nakeshia H 1

a reactive element? or is it non-reactive?

2007-11-29 11:50:33 · 2 answers · asked by Ari L 2

I have to do this reseach project for my chemistry class, and I'm having a tough time trying to pick on element. Any suggestions,, you can suggest more than one too. Thanks so much.

2007-11-29 11:48:05 · 2 answers · asked by Dana M. 3

Like interesting facts and things

2007-11-29 11:43:14 · 2 answers · asked by Anonymous

Im doing a project which Im adding milk, Tide, salt, and oil to different cups of water and seeing which substance best prevents the evaporation of water. How do I measure how much WATER evaporated and not the other substances? any ideas?

2007-11-29 11:25:52 · 4 answers · asked by fluorine DX4 3

2007-11-29 11:24:15 · 3 answers · asked by AskMe 2

is this statement true H2(g)+Cl2(g)-->no reaction if so why? why not?

2007-11-29 11:21:47 · 2 answers · asked by Ms.Q's 1

Please respond soon guys because this is a project due in 2 days at school...

2007-11-29 11:19:43 · 5 answers · asked by Rawan 2

2007-11-29 11:02:49 · 6 answers · asked by Anonymous

2007-11-29 10:52:13 · 1 answers · asked by Anonymous

does anyone know?

2007-11-29 10:01:28 · 2 answers · asked by Anonymous