Chemistry - November 2007

2007-11-13 11:47:33 · 2 answers · asked by nash 1

Yes, I can be a total dunce when it comes to moles, but I got every other problem except these three which threw me off.
1.) Calculate the mass of calcium oxide that will be formed when 0.48g of calcium is burned in 0.32g of oxygen. The equation is:
2Ca + O2 = 2CaO (Answer: 0.67g of CaO)
2.) Calculate the mass of zinc bromide that can be formed when 1.00g of zinc is mixed with 1.00g of bromine. The equation is:
Zn + Br2 = ZnBr2 (Answer: 1.41g of ZnBr2)
3.) What mass of sodium chloride would be expected of 0.460g of sodium with 0.426g of chlorine gas? The equation is:
2Na + Cl2 = 2NaCl (Answer: 0.702g of NaCl)
The answers are the "correct" answers listed on the answer sheet by the way. So, how did we get those? Help, plz! Thanx! I'd be lost without your intelligence lol

2007-11-13 11:42:10 · 1 answers · asked by mikita_daita 1

Well im doing a project about ammonia and i cant find any where on how 3 ammonia(NH3) atoms would connect together. Would they be polar? or connected at the equator?

2007-11-13 11:41:00 · 1 answers · asked by Anonymous

do you guys know how to convert : in Hg to kPa?
thanks

2007-11-13 11:36:55 · 1 answers · asked by `~,,..._+*-=^_^=-*+_...,,~` 2

2007-11-13 11:36:26 · 3 answers · asked by Anonymous

1. Consider the hydrocarbon pentane, C5H12 (molar mass 72.15 g).

(a) Write the balanced equation for the combustion of pentane to yield carbon dioxide and water.

(b) What volume of dry carbon dioxide, measured at 25°C and 785 mm Hg, will result from the complete combustion of 2.50 g of pentane?

(c) Under identical conditions, a sample of an unknown gas effuses into a vacuum at twice the rate that a sample of pentane gas effuses. Calculate the molar mass of the unknown gas.

2. Answer the following questions related to hydrocarbons.

(a) Determine the empirical formula of a hydrocarbon that contains 85.7 percent carbon by mass.

(b) The density of the hydrocarbon in part (a) is 2.0 g L/l at 509°C and 0.948 atm.

1. Calculate the molar mass of the hydrocarbon.

2. Determine the molecular formula of the hydrocarbon.

2007-11-13 11:30:16 · 2 answers · asked by stylinpat 2

a) use a magnet to attract the iron filing
b) dissolve the salt in water, then filter and evaporate
c) decant the salt
d) both(a) and (b)

2007-11-13 11:29:30 · 3 answers · asked by Anonymous

2007-11-13 11:28:35 · 1 answers · asked by xxiangel 2

Mass percent is grams of solute over liters of solution (hydrogen peroxide)

I know i have .46 moles in .00872 liters and the density is 1.00g/ml

what is the %m/m?

2007-11-13 11:26:17 · 0 answers · asked by shirah d 2

What is the equation for aluminum metal and water?

is it Al(s) +2H20(l)-->Al(OH)2(aq)+H2(g)

2007-11-13 11:19:58 · 2 answers · asked by Anonymous

At STP, 0.160 L of a gas weighs 0.400 g. Calculate the molar mass of the gas. (g/mol)

any help is appreciated

2007-11-13 10:53:04 · 1 answers · asked by loveall 3

That's all my prelab asks. What does that mean and what is the answer? I put "When all of the reactants involved have fully reacted, leaving excess product behind."

2007-11-13 10:46:18 · 1 answers · asked by E 2

2007-11-13 10:43:10 · 3 answers · asked by mr misery 1

A. [Cu(NH3)4]^2+
B. [AgNH3)2]^+
C. [Pt(NH3)2Cl2]
D. [Co(en)2Cl2]^+
E. None of these has a coordination number of 6

2007-11-13 10:39:15 · 3 answers · asked by aweeks_06 1

How do you order these from largest to smallest atomic radii? How do you know which is larger?


Cl-
Al3+
Na+
F-
Mg2

2007-11-13 10:27:04 · 1 answers · asked by Aspire 3

ok so
pWrite the balanced chemical equation for the reaction of zinc metal Zn(s) in aqueous copper (II) bromide, CuBr2 (aq)

___________(s)+__________ (aq) -> ______(aq)
+ _______(s) (single replacement reaction


2. how many moles is in .69 grams of Zn??


3 Using the answer above and the proper mole ration from the balanced equation , how many moles of the solid copper will form??



4.Finall how many grams of copper are in the moles of copper calculated in step 3


5 was the reaction endo thermic or exo thermic???




guys plzz help out and explain wat u did im having a hard time wid chemistry and the teacher shouldnt even have a teaching license

2007-11-13 10:20:43 · 7 answers · asked by Anonymous

A. Enthalpy
B. Resonance
C. Entropy
D. Hydrogen Bonding
E. Hydration

2007-11-13 10:14:13 · 1 answers · asked by aweeks_06 1

i need some help on some chemistry homework!!! i need to know the chemical formulas of baking powder, cornstarch, sugar,vinegar and iodine. and i need the scientific names of them too!!!
please help!

2007-11-13 09:45:49 · 2 answers · asked by Chelsea Grace <3 3

2007-11-13 09:18:54 · 3 answers · asked by canadiangeoguy 2

2007-11-13 09:17:04 · 6 answers · asked by canadiangeoguy 2

2007-11-13 09:15:56 · 3 answers · asked by chica magneta 1

Ok for

H2S (aq) --> S(s) acidic I got
**** H2S + e- --> S +2H2

NO3-(aq) --> NO2- (aq) basic I got
**** 2NO3- --> 3NO2-+ 2e-

I-(aq) --> IO3- (aq) acidic I got
****i cant finish this one I2- +3H2) +e- --> IO3-+H2O

Im not sure on the rest either..I might have gotten the last one but im not sure....Please help me

VO2+ (aq) --> V3+ (aq) acidic

Cl2O7 (g) --> ClO2- (aq) basic

NO (g) --> NO3- (aq) acidic

NO2- (aq) --> N2(O2)2- (aq) basic

Se(O3)2- (aq) --> Se(O4)2- (aq) basic
***2e- +4SeO3 --> 3SeO4

2007-11-13 09:12:32 · 1 answers · asked by Anonymous

2007-11-13 09:11:58 · 12 answers · asked by canadiangeoguy 2

is NH3 a:
a) nonpolar covalent bond
b) nonpolar ionic bond
c) polar covalent
d) ionic bond

2007-11-13 09:11:22 · 2 answers · asked by Anonymous

And yes... there is something that has ALL the elements.
Correct or closest answer gets 10 pts.
Thanks!

2007-11-13 09:05:18 · 9 answers · asked by Anonymous

Microwaves are used to heat food in microwave ovens. The microwave radiation is absorbed by moisture in the food. This heats the water, and as water becomes hot, so does the food. How many photons having a wavelength of 3.00 mm would have to be absorbed by 1.00 g of water to raise its temperature by 1.00C? It takes 4.184 J of energy to heat this much water.

2007-11-13 09:04:42 · 2 answers · asked by G.G. 1

Does the OH become a carbonyl or does an E2 reaction occur where OH gets protonated by water and is lost as H30 and becomes a double bond between 2 and 3 carbon. On top, does the CN serve as the leaving group?

2007-11-13 08:56:25 · 1 answers · asked by Little Foot 3

Which scientist was the first to conclude through experimentation that atoms have positive charges in their nuclei?

2007-11-13 08:24:54 · 1 answers · asked by jo_beanman 1

chemistry

2007-11-13 08:09:27 · 1 answers · asked by jo_beanman 1

Just need to find a way to decide that.
Mix the acid with something or whatever!

Thanks.

2007-11-13 08:08:05 · 4 answers · asked by Anonymous