Chemistry - November 2007

If one assumes the volumes are additive, what is the [Cl-] in a solution obtained by mixing 225 mL of 0.625 M KCl and 615 mL of 0.385 M MgCl2?
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i got 1.713 is it right???

2007-11-18 11:27:39 · 3 answers · asked by coca 1

Calculate the molar solubility of SrCO3 (Ksp = 5.4 10-10) in each of the following.
0.14 M Sr(NO3)2

2007-11-18 11:26:11 · 1 answers · asked by Ecka 1

2007-11-18 11:19:53 · 1 answers · asked by timmy t 1

If one assumes the volumes are additive, what is the [Cl-] in a solution obtained by mixing 225 mL of 0.625 M KCl and 615 mL of 0.385 M MgCl2?

2007-11-18 11:07:28 · 1 answers · asked by coca 1

1. 6.5
2. 7.5
3. 5.5

2007-11-18 11:01:54 · 1 answers · asked by yakov59 1

Can you balance these? I tried to type it so it's understandable. I would greatly appreciate your help. After the equations are balanced I can do the rest of the problems myself.


(NH4)2 SO4(aq) + Ca(OH)2(c) yields CaSO4(c) + NH3(g) + H2O(l)


AgC2H3O2(aq) + Na2PO4(aq) yields Ag3PO4(c) + NaC2H3O2(aq)

2007-11-18 10:59:47 · 2 answers · asked by Fast boy + sexy boy + doglover 7

1) 7.85 L

2) 6.67L

3) 7.50 L

4) 7.63 L

5) 5.79 L

2007-11-18 10:57:07 · 2 answers · asked by goodygood800 1

Use the information to determine if the pair of elements are isotopes or different elements.

1. Element D has 6 protons and 7 neutrons.
Element F has 7 protons and 7 neutrons.

2. Element J has 27 protons and 32 neutrons.
Element L has 27 protons and 33 neutrons.

3. Element X has 17 protons and 18 neutrons.
Element Y has 18 protons and 17 neutrons.

4. Element Q has 56 protons and 81 neurtons.
Element R has 56 protons and 82 neutrons.

5. Element T has an atomic nu,ber or 20 and an atomic mass of 40.
Element Z has an atomic number of 20 and an atomic mas of 41.

6. Element W has 8 protons and 8 neutrons.
Element V has 7 protons and 8 neutrons.

How can you tell which is which? I am really confused. I don't know how to tell if it is an isotope or a different element. Please help!?

2007-11-18 10:51:27 · 4 answers · asked by Emily 2

Write a word equation for:
a) A gas causes a glowing splint to burst into flames reacts with sugar to produce water and gas that turns limewater milky.

b) Sodium metal reacts with water to produce sodium hydroxide and a gas that reacts explosively to a blazing splint.

c) Natural gas(mathane)burns in oxygen to produce one product that turns limewater milky, and a second product with fixed points of 0 degrees Celsius and 100 degrees Celsius.

2007-11-18 10:49:56 · 1 answers · asked by Zayka 1

Can I have the complete history of the atomic number 23 which is Vanadium?

2007-11-18 10:45:19 · 2 answers · asked by ~Katie~ 2

Zn(s) + Cu2+(aq) Zn2+(aq) +Cu(s)
Under standard conditions, what is the maximum electrical work, in kilojoules, that the cell can accomplish if 40.9 g of copper are plated out?

2007-11-18 10:40:26 · 1 answers · asked by softshimmer 2

2007-11-18 10:36:06 · 4 answers · asked by Dwill 1

This is a question on a chemistry lab that I recently did and I don't understand it at all! Please give me some help!!!!

It is possible to get a false-positive or a false-negative result when testing for ion? Propose a situation that could lead to a false-positive for a particular ion. Choose a different ion and show how a false negative could result. Which do you think is more likely to happen, a false positive or a false neagative result? Explain your reasoning.

2007-11-18 10:25:24 · 1 answers · asked by ♥PaIgE♥ 3

A voltaic cell is based on the following reaction.
Sn(s) + I2(s) Sn2+(aq) + 2 I-(aq)
Under standard conditions, what is the maximum electrical work, in joules, that the cell can accomplish if 81.5 g of Sn is consumed?

2007-11-18 10:24:02 · 1 answers · asked by softshimmer 2

would you normally expect ∆H° to be positive or negative for a voltaic cell? Justify your answer.

can anyone please help me answer this question?
thanks

2007-11-18 10:15:19 · 1 answers · asked by abc 1

Using the given bond energies (BE), calculate ΔHorxn for the reaction:
CH4(g) + Cl2(g) => CHCl3(g) + HCl(g) (not balanced)
Bond BE (kJ/mol) Bond BE (kJ/mol)
C-H 413 C-C 347
C=C 614 C-Cl 339
H-Cl 427 Cl-Cl 243

Answer = -330kj

How would I solve a question like this?

2007-11-18 10:14:17 · 3 answers · asked by Johnson H 2

I know the answer is 3 or 4. Can someone please break this down in children terms on how I would be able to answer this question. Please show me steps so i could answer similar questions like this.

2007-11-18 10:10:55 · 2 answers · asked by Johnson H 2

Calculate the voltage of the following cell:
Zn │ Zn^2+ (0.10M) ║ Cu^2+ (0.40M) │ Cu

can anyone please help me solve this problem? and show how it is done.
thank you

2007-11-18 10:10:21 · 1 answers · asked by abc 1

What is the new temperature in degrees Celcius?? Please explain steps---Thank YOu

2007-11-18 10:05:43 · 1 answers · asked by sarah 2

A fluorescent mineral absorbs black light from a mercury lamp. It then emits visible lights with a wavelength 520 nm. The energy not converted to light is converted to heat. If the mineral has absorbed energy with a wavelength of 320 nm, how much energy (in kJ/mol) was converted to heat?

I cant seem to visualize/get started on this problem, I imagine Ill have to find frequency to get the energy, but I dont see how ill end up with kJ/mol... Any help would be much appreciated.

2007-11-18 09:54:35 · 2 answers · asked by Coastal 2

Metallic magnesium can be made by the electrolysis of molten MgCl2.

(a) What mass of Mg is formed by passing a current of 5.90 A through molten MgCl2 for 2.20 days? in grams

(b) How many minutes are needed to plate out 14.80 g Mg from molten MgCl2, using 6.60 A of current? in minutes

2007-11-18 09:50:55 · 3 answers · asked by softshimmer 2

a sampe of sucrose, C12H22O12, is contaminated by sodium chloride. when the contaminated sample is burned in a bomb calorimeter, sodium chloride does not burn.

what is the percentage of sucrose in the sample if a temperature increase of 1.67 degrees C is observed when 3.000g of sample is burned in the calorimeter? sucrose gives off 5.64 times 10 to the third kJ/mol when burned.

the heat capacity of the calorimter is 22.51 kJ/degrees C

2007-11-18 09:45:30 · 1 answers · asked by belleswan 3

2007-11-18 09:44:52 · 1 answers · asked by IbeME 1

I am applying thermal stress on a material with a melting point=160 degree centigrade, But in 95 degree after 3 days it changes to liquid (in lose capped vials). I think the name of this is melting but why in every reference even in Merck index it is stated that this chemical has a higher Melting point than 95?

2007-11-18 09:44:30 · 1 answers · asked by farnaz . 1

Please explain this to me. Thanx!

2007-11-18 09:41:58 · 2 answers · asked by Anonymous

is the smoke relevant to the ratio of magnesium to oxygen (Mg:O) in the chemical equation, 2Mg + O2 = 2MgO?

2007-11-18 09:38:45 · 2 answers · asked by Anonymous

Specifically these formulas NaOH, CH3CH2OH , C3H8O, NH3 , NaOCl , NaCl, C12H22O11, CH3COOH, NaHCO3, H202, Na2C03,NaF.
Also i want to know if an atom can have multiple anions or cations for example C3H8O is it correct if I say it has one cation and two anion. Thank you

2007-11-18 09:35:23 · 2 answers · asked by hnz789 1

This is the specific question that I was asked that I can't answer:

Carbon is a nonmetal, silicon is a metalloid, and tin is a metal. They are all in the same family. Yet, they all possess different behaviors! Why? If you can properly answer this question, then you truly have a grip on this unit.

Anyone know? Thanks :)

2007-11-18 09:30:45 · 1 answers · asked by Leslie 2

completely with 8.0g of magnesium? 2Mg + O2 --- 2MgO
thanks for your help!!!!

2007-11-18 09:21:05 · 2 answers · asked by sarah 2

At STP, 762 ML of a gas has a mass of 1.02g. If the gas has an emphirical formula of CH3, what is the molecular formula of the compound.

2007-11-18 09:17:57 · 2 answers · asked by mikala m 2