Chemistry - October 2007

Calculate the energy difference (E) for the photon absorbed when a hydrogen atom undergoes a transition from n = 1 to n = 4 for 1 mol H atoms.

2007-10-29 10:02:21 · 1 answers · asked by Anonymous

A 520. g piece of copper tubing is heated to 91.7°C and placed in an insulated vessel containing 57.0 g of water at 37.0°C. Assuming no loss of water and heat capacity for the vessel of 10.0 J/K, what is the final temperature of the system (c of copper = 0.387 J/g·K)?

2007-10-29 09:49:59 · 1 answers · asked by Heman8689 1

A) dissovling agent of a solution
B) the liquid portion of a solution
C) usually water in living cells
D) the substance that is dissolved in solution
E) the dissolving agent of a soluton which is usally oxygen in living cells

2007-10-29 09:48:38 · 3 answers · asked by Anonymous

7. Copper and sulfuric acid react to form copper(ll) sulfate and water and sulfur dioxide.
8. Hydrogen gas and nitrogen monoxide react to form water and nitrogen gas.

2007-10-29 09:43:47 · 3 answers · asked by Diamond E 1

2007-10-29 09:36:36 · 2 answers · asked by love*pink 3

Please work it out??

2007-10-29 09:35:01 · 2 answers · asked by Anonymous

Toluene, C7H8, is used in the manufacture of explosives such as TNT (trinitrotoluene). A 1.500 g sample of liquid toluene was placed in a bomb calorimeter along with excess oxygen. When the combustion of the toluene was initiated, the temperature of the calorimeter rose from 25.000°C to 26.413°C. The products of the combustion are CO2(g) and H2O(l), and the heat capacity of the calorimeter was 45.06 kJ°C-1. The reaction was
C7H8(l) + 9O2(g) 7CO2(g) + 4H2O(l).

1) The number of joules liberated by reaction of the 1.500 g of toluene is __?___.

2) The number of joules that would be liberated under similar conditions if 1.000 mol of toluene were burned is __?___.

If you could explain or show work, greatly appreciated. Thank you!

2007-10-29 09:26:15 · 1 answers · asked by maxizdaname 1

4. Potassium metal and chlorine gas combine to form potassium chloride.

5. Aluminum and hydrochloric acid react to form aluminum chloride and gas hydrogen gas.

6.Calcium Hydroxide and phosphoric acid react to form calcium phosphate and water.

2007-10-29 09:24:15 · 5 answers · asked by Diamond E 1

Our project is about paint! How do you differentiate between physical and chemical properties? Classify substances based on the physical and chemical properties? Site evidence o physical and chemical change? Idenify different kinds of energy given o or used in reactions?dentify reactants and products in any reaction? Demonstate that mss is conserved in all reactions?

2007-10-29 09:20:57 · 2 answers · asked by Anonymous

i need some example energy bond values for ionic, covalent and metallic bonding...please help.

2007-10-29 09:09:07 · 3 answers · asked by Anonymous

when water is in a river, lake or water source a city gets there water from is cleaned it goes through all of the processes and then in to homes used water goes through pipes to a cleaning plant then back into the river so how is it clean

if you add the fact about water getting evaporated then it rains back down how can you say that water isnt contaminated.

2007-10-29 09:04:34 · 3 answers · asked by Andreu 2

2007-10-29 09:02:28 · 7 answers · asked by Anonymous

Please help me. I need a chemistry tutor. Just give me your email address and I'll email you some of my questions when I get them. Have a nice day. Thank you.

2007-10-29 08:58:47 · 3 answers · asked by Chrishonda Alston 3

A) C4
B) C4H10
C) C3H8
D) C6H12O6
E) These are all organic molecules.

2007-10-29 08:51:57 · 6 answers · asked by Anonymous

Consider carbon-12, carbon-13 and carbon-14 (the numbers indicate atomic mass). Which of these forms of carbon is an isotope?
A) Carbon-12
B) Carbon-13
C) Carbon-14
D) none are isotopes
E) all are isotopes

2007-10-29 08:50:53 · 8 answers · asked by Anonymous

From this information alone, you can predict that
A) argon has more neutrons than chlorine.
B) argon is more chemically reactive than chlorine.
C) argon will more readily ionize than chlorine.
D) chlorine is more chemically reactive than argon.
E) chlorine has more neutrons than argon.

2007-10-29 08:49:00 · 2 answers · asked by Anonymous

if you have proof on websites then that would really help

2007-10-29 08:38:16 · 2 answers · asked by Anonymous

I had to carry out these experiments:
Mix calcium carbonate with dilute hydrochloric acid in a test tube with a side arm and dip the delivery in a test tube containing calcium hydroxide and cork the test tube to trap any gases. A gas was formed and a white precipitate formed with the CaOH. my first equation was:
CaCo3+2HCl--> CaCl2+H2O+Co2.... I need another equation .. something to do with the Co2 forming something.....

The next experiment was to mix potassium manganate (VII) with a few cm^3 of concentrated hydrochloric acid.....and a gas was given off.. something like chlorine.... what would be the equations?

and can you tell me how these gases were formed?

2007-10-29 08:27:58 · 1 answers · asked by petra_sweety 3

I can't figure this out for the life of me. HELP!!

Acetic acid, HC2H3O2, is the sour constituent of vinegar. In an experiment, 3.16 g of acetic acid was burned.

HC2H3O2(l) + 2 O2(g) 2 CO2(g) + 2 H2O(l)

If 45.9 kJ of heat evolved, what is change in H (enthalpy) per mole of acetic acid?

Thanks so much!

2007-10-29 07:52:24 · 1 answers · asked by 23chromosomes 4

When I add 1.50 mL of 0.69 M NH3 to 1.0 L of 1E-3 M FeSO4, what will Q be?

I determined when NH3 reacts with H2O, it forms 3.52E-3 M OH.
Was I suppose to do this?
How do I calculate Q from here?

2007-10-29 06:14:21 · 1 answers · asked by Tiffany 4

i need to hand in coursework tommorow please help and if possible could you also mention the site you got the information of please and thanks

2007-10-29 06:07:43 · 2 answers · asked by ebrahim m 2

2007-10-29 05:55:32 · 2 answers · asked by Anonymous

2007-10-29 05:53:13 · 1 answers · asked by Anonymous

2007-10-29 05:47:04 · 1 answers · asked by Anonymous

given the following Formation Constants(Kf) for
Kf ( Ca^+2 - EDTA ) = 5.0x10^10
kf ( Pb^+2 -EDTA ) = 1.1x10^18

2007-10-29 05:41:16 · 6 answers · asked by crazzy_em 3

In addition to continuous radiation, fluorescent lamps emit sharp lines in the visible region from a mercury discharge within the tube. Much of this light has a wavelength of 436 nm. What is the energy (in J) of one photon of this light?

2007-10-29 05:39:22 · 1 answers · asked by jnester0289 1

2007-10-29 05:15:22 · 16 answers · asked by Sunshine 1

Butane, C4H10, is a component of natural gas that is used as fuel for cigarette lighters. The balanced equation of the complete combustion of butane is:

2C4H10(g) + 13O2(g)->8CO2(g) + 10H2O(l)


At 1.00atm and 23*C , how many liters of carbon dioxide are formed by the combustion of 1.00g of butane?

For the above...I have converted 1g of butane=0.017204mol (1g*1mol/58.1234gC4H10) = 0.017204mol C4H10
Then: mol CO2= 1g*1mol/44.011g = 0.2272mol CO2
(if these are the correct initial approach????)

The temp=23*C + 273.15K = 296.15K
The Volume=????
Constant R I will use is: 0.082058L atm mol K
n...?????

I know that I should somehow divide the 8moles of CO2 with the 2moles of C4H10...but not sure how to do this. I tried 0.547L as an answer but it wasn't correct.

Please help and point out what I was doing incorrectly. I thought that I had it figured, but I figured incorrectly.
Thank you in advance!!

2007-10-29 03:14:30 · 2 answers · asked by Anonymous

2007-10-29 02:54:49 · 4 answers · asked by babbygril_69 1

2007-10-29 02:42:31 · 3 answers · asked by Anonymous