Chemistry - March 2007

2007-03-07 15:35:35 · 2 answers · asked by barnold4 1

How many grams of sulfur (S8) would have to be dissolved in 145.0 g of carbon tetrachloride to lower the freezing point by 2.10 degrees celsius?


kf = 29.8 K-kg/mol for CCl4

2007-03-07 15:25:58 · 1 answers · asked by guitarx313 1

1. Determine the number of protons, electrons, and neutrons in each of the following isotopes:
a. sodium-23
b. calcium-40
c.64/29Cu
d. 108/47Ag

2.Write the nuclear symbol and hyphen notation for each of the following isotopes:
a. mass number of 28 and atomic number of 14
b. 26 protons and 30 neutrons
c. 56 electrons and 82 neutrons

4.to two decimal places, what is the relative atomic mass and the molar mass of the lement potassium, K?

5.Determine the mass in grams of the following:
a. 2.00 mol N
b. 3.01 x 10(to the power of 23), atoms F

6. determine the amount of moles of the following:
a. 12.15 g Mg
b. 1.50 x 10 (to the power of 23), atoms F

7. Determine the number of atoms in the following:
a. 2.50 mol Zn
b. 1.50 g C


i would very much apreciate if you could give me these answers!!! thank you very much, and if you dont know them all just answer the ones you know, once again thank you

2007-03-07 15:18:43 · 1 answers · asked by Whisper G 1

2007-03-07 15:08:16 · 9 answers · asked by Vanessa1027 1

Organic chemistry 1 and 2 I have to take as a requirement for my major. I don't feel like I'm really strong in chemistry, but I am good in biology. How is organic chemistry different from general chemistry?

2007-03-07 15:05:28 · 8 answers · asked by Anonymous

How many grams of sulfur (S8) would have to be dissolved in 120.0 g of carbon tetrachloride to lower the freezing point by 1.70 degrees celsius?


kf = 29.8 K-kg/mol for CCl4

2007-03-07 14:55:43 · 2 answers · asked by Anonymous

If 13.30 grams of RbCl are dissolved in water to make a solution of 0.224 L, the density is found to be 1.044 g/cm3. Calculate the molarity of the solute.

2007-03-07 14:55:17 · 1 answers · asked by Anonymous

1.70 degrees celsius? Kf= 1.86 K-kg/mol for water.

2007-03-07 14:44:16 · 2 answers · asked by Nicole P 1

2007-03-07 14:38:46 · 5 answers · asked by tlessard@rogers.com 1

2007-03-07 14:35:51 · 6 answers · asked by Monica S 1

assume that aqueous Ba(NO3)2 and Na2CO3 are mixed.

what ions are present in the solution?
what precipitates are possible from the reaction?
put quotations around the precipitate that is soluable.
write the complete chemical equation for the reaction.
write the next equation.

or all of this for Pb(NO3)02 and NH4I

i really dont understand how to do this type of a problem, and any help would be sincerly appreciated. thank you!

2007-03-07 14:34:29 · 1 answers · asked by carr0t 1

to lower the freezing point by 1.90 degrees celsius?


kf = 1.86 K-kg/mol for water

2007-03-07 14:31:38 · 1 answers · asked by Anonymous

2.60 atm. The temperature is 25o C. What is the concentration of Nitrogen in the water?
Give your answer in g/L .
The vapor pressure of water at 25.0oC is 23.8 mm Hg.


Note that kH has units of mol/L / mm Hg

2007-03-07 14:29:58 · 2 answers · asked by Anonymous

what is the specific heat of aluminum if the temp of a 28.4g sample is increased by 8.1 degrees Celsius when 207 J of heat is added?

2007-03-07 14:13:10 · 1 answers · asked by Anonymous

12 mg of a certain protein was dissolved in water to make a solution of 1.00 mL at 20C. If the osmotic pressure is 1.20 torr, what is the molecular mass of the protein?

2007-03-07 14:10:55 · 1 answers · asked by tiggerx313 1

How many grams of sulfur (S8) would have to be dissolved in 145.0 g of carbon tetrachloride to lower the freezing point by 2.10 degrees celsius?


kf = 29.8 K-kg/mol for CCl4

2007-03-07 14:10:40 · 2 answers · asked by tiggerx313 1

I'm sort of stumped on this one. If someone knows the answer that would be great.

2007-03-07 14:02:30 · 2 answers · asked by Andrew\ 1

the following are fill-in-the-blank science stuff that has to do with chemistry.

Chemistry is the science of matter and its _h_____.(7letters)

Substances made of two or more different kinds of molecules are
_i______.(8 letters)

Remenber this all has to do with SCIENCE AND CHEMISTRY!

2007-03-07 14:00:35 · 1 answers · asked by amy T 2

for example, how many ions are in each of these:

lithium nitrate: LiNo3

lead (II) chlorate: Pb(ClO3)2

ammonium phosphate: (NH4)3PO4

sugar water: C12H22O11

2007-03-07 13:59:56 · 1 answers · asked by Maria18 2

2007-03-07 13:50:19 · 1 answers · asked by jOan . 1

1. Calcium carbonate decomposes when heated strongly. The decomposition is represented by the equation
CaCO3(s) -(arrow) CaO(s) + CO2(g)
The mass of calcium oxide produced from 25g of calcium carbonate is about
a) 25g
b) 14g
c) 16g
d) 8g

2. Washing soda crystals have the formula, Na2CO3.10H2O. If 10.0g of the crystals are heated to remove all the water, the mass loss would be
a) 0.50g
b) 0.63g
c) 3.70g
d) 6.29g

Thankyou. Please help chemistry wizzes.

2007-03-07 13:47:45 · 2 answers · asked by Anonymous

and can u pLease give me an example.. thanks!

2007-03-07 13:45:10 · 1 answers · asked by jOan . 1

2007-03-07 13:43:05 · 4 answers · asked by Winston C 1

1. The complete combustion of octane (C8H18) in a car engine is best described by the equation
a) C8H18(g) + O2(g) -(arrow) CO2(g) + H2O(g)
b) C8H18(g) + 17O2(g) -(arrow) 8CO2(g) + 18H2O(g)
c) 2C8H18(g) + 34O2(g)-(arrow) 16CO2(g) + 18H2O(g)
d) 2C8H18(g) + 25O2(g) -(arrow) 16CO2(g) + 18H2O(g)

2. Natural gas which is used for domestic heating, burns according to the equation CH4(g)+2O2(g) - (arrow) CO2(g) + 2H2O(g)
In this process, if complete raction occurs,
a) 16g of methane produces 18g of water
b) 1g of methane produces 12g of carbon dioxide
c) 1g of methane reacts with 4g of oxygen
d) 4g of methane reacts with 8g of oxygen

3. If equal masses of each of the followign are burned in excess oxygen, which will give the greatest mass of CO2?
a) CH4
b) CH3OH
c) C2H2
d) CH3CH2OH

Thankyou. Please help Chemistry wizzes! Please be 100% sure of your answers. Thanks.

2007-03-07 13:40:58 · 2 answers · asked by Anonymous

1. Which of the following statements, comparing the products of any chemical reaction with reactants, is true?
a) There are always as many molecules after the reaction before.
b) Their total number of moles is always the same
c) Their total mass is always the same
d) The products always possess the same amount of energy as the reactants.

2. For the reaction Ng(g)+3H2(g) -(to, should be arrow) 2NH3(g), the total mass of products divided by the total mass of reactants is
a) 2.00
b) 0.25
c) 0.50
d) 1.00

3. Carnon monoxide burns in oxygen according to the equation
2CO(g) + O2(g)- (arrow sign) 2CO2(g)
The number of moles of oxygen required for the combustion of 28g og carbon monoxide is
a) 2.00
b) 1.00
c) 0.50
d) 0.25

Thankyou for helping. Please help chemistry wizzes. Please be 100% sure of your answers.

2007-03-07 13:34:22 · 2 answers · asked by Anonymous

2007-03-07 13:24:48 · 3 answers · asked by rungedhar 1

i have no idea how to do this my teacher does not know how to teach forreal....

How many moles of KCIO3 must decompose in order to produce 9 moles of oxygen gas?
2KCIO3(s)>2KCI(s)+3O2(g)




How many grams of KCIO3 are required to produce 7.50 moles of KCI?
2KCIO3(s)>2KCI(s)+3O2(g)


How many moles of water are produced from 58g of oxygen gas?
___H2+___02>___H2O



Iron reacts with chlorine gas to form iron (III) chloride. How many grams of iron (III) chloride are formed from 112g of iron? (first write the balanced equation)

2007-03-07 13:21:46 · 5 answers · asked by moody 1

2007-03-07 13:03:27 · 4 answers · asked by Tim J 1

1.

a.What is the molarity of a solution of nitric acid if .216 g of barium hydroxide is required to neutralize 20 mL of nitric acid?

b. A lead storage battery needs sulfuric acid to function. The recommended minimum concentration of sulfuric acid for maximum effectivity is about 4.8 M. A 10 mL sample of battery acid requires 66.52 mLof 1.325 M KOH for its complete neutralization. Does the concentration of battery acid satisfy the minimum requirement? (Note: Two H+ ions are produced for every mole of H2SO4.)

Please explain/show all work.

2007-03-07 13:01:27 · 2 answers · asked by nirmal 1

how do you find the [OH-] when given the pH. I know to find the [H+] from the pH is 10 times the negitive power, but i dont remember how to get the OH please help!

2007-03-07 12:55:58 · 2 answers · asked by matthew 5