Chemistry - June 2007

A student obtains the following Rf values for the seven dyes in the solvents noted

dye -> water -> acetonitrile -> ethyl -alcohol
B1 -> .57 -> .94 -> .52
B2 -> .36 -> .34 -> .26
R3 -> .42 -> .19 -> .30
R40 -> .48 -> .51 -> .33
G3 -> .31 -> .32 -> .39
Y5 -> .34 -> .44 -> .55
Y6 -> .46 -> .66 -> .46

Which solvent shoes the greatest resolution of the dyes and should therefore be used in the subsequent analysis of the student unknown.

For that solvent, which pair of dyes is likely to be most easily mis-reported?

2007-06-06 13:35:35 · 1 answers · asked by Anonymous

(Na=23, S=32, O=16)

a. 178g; b. 284g; c. 356g; d. 710

(Please tell me how to solve this problem.)

2007-06-06 13:29:20 · 6 answers · asked by missmathers 2

A student ignores the instruction to equilibrate the solvent chamber and does not place a cover on the chamber during the development of the chromatograph. At the end of the development, no solvent front is visible on the chromatogram. The student assumes that the solvent front is at the top of the chromatogram. Is this assumption likely to be correct?

2007-06-06 13:27:38 · 5 answers · asked by Anonymous

2007-06-06 13:19:16 · 1 answers · asked by Ruby D 1

2-methyl-1-butene reactes with hydrogen bromide producing:
...............CH3
CH3CH2+CH3
...............Br

(the '+' stands for crossing lines)

I got a qn asking 'write a reaction mechanism for this process showing the movement of electrons with arrows'
I have no idea what to do! Any suggestions?

2007-06-06 12:58:54 · 1 answers · asked by Anonymous

What is the child's from of the scientific method?
I thought it was:
1. Question
2.Hypothesis
3. Materials
4. Procedure
5. Observation
6. Results
7. Conclusion

I wasn't sure, so please let me know if this is correct. Thanks.

2007-06-06 12:50:31 · 3 answers · asked by Anonymous

i need the pH of these...for chemistry

2007-06-06 12:31:01 · 4 answers · asked by Anonymous

acrylic latexes will coalesce to form films - however, if there is no electron sharing between adjacent acrylic particles; does that mean the cohesion forces are entanglement and/or ionic bonding? and what are the adhesion forces that "cling" it to the substrate?

2007-06-06 12:27:19 · 1 answers · asked by taulmachof 1

How would i balance this equation

H2SO4+NaOH Forms NaSO4+H2O

2007-06-06 12:26:43 · 2 answers · asked by jf 3

How do you locate a stereocentre on a compound?

2007-06-06 12:19:18 · 4 answers · asked by Anonymous

Locate the stereogenic centre in 3-methylhexane

CH3CH2CHCH2CH2CH3
(CH3 branches off the underside of the plain CH)

2007-06-06 12:18:10 · 3 answers · asked by Anonymous

a sample of ethane, C2H6, is burned in O2. The products of combustion are carbon dioxide and water; what is the mass of the carbon dioxide produced if the mass of the ethane consumed is 20.5 grams? (Assume 100% comsumption of the ethane.)

2C2H6 + 7O2 (yields>>) 6H2O + 4CO2

2007-06-06 11:48:51 · 2 answers · asked by Aubrie 1

fill in the blanks plzz

2007-06-06 11:33:50 · 1 answers · asked by Anonymous

2007-06-06 11:33:17 · 1 answers · asked by Anonymous

How many liters of nitrogen gas are needed to react with hydrogen gas to produce 5.40 liters of ammonia at STP?
N2 + 3H2 --> 2NH3

Limiting Reactants
What is the limiting reactant when 24g H2 and 35g O2 react to produce water? 2H2 + O2 --> 2H2O

2007-06-06 11:18:26 · 1 answers · asked by Buttons. 1

a. Is the bond type between a phosphorus atom and a fluorine atom ionic, polar or nonpolar covalent? What calculations allowed you to derive at this?

b. Write the Lewis Dot Formula for the molecule formed from these two elements.

c. What is hte shape of the molecule?

d. Is this molecule asymmetrical or symmetrical in shape?

e. Is the molecule polar of nonpolar overall? Explain reasoning in terms of VSEPR Theory

2007-06-06 11:17:14 · 3 answers · asked by San Fran Kid 2

A. trace elements
B.radio active tracers
C.carbon tracers
d. alpha emmiting isotopes

2007-06-06 11:17:07 · 2 answers · asked by master x 2

A. iron
B. oxygen
C silicon
D magnesium

2007-06-06 10:48:41 · 8 answers · asked by master x 2

Graham's Law
Q: How many times faster does oxygen effuse than CO2?

Dalton's law of partial pressures.
Q: Gases A,B, and C are in an enclosed container. The partial pressure of A is 2.0 atm, the partial pressure of C is 3.0 atm, and the total pressure in 10.0 atm. What is the partial pressure of B?

Please tell me answers and give me some explanations.

2007-06-06 10:36:49 · 2 answers · asked by Buttons. 1

[H3O+]=1.0*10`3M? pH=6.00? pOH=10.00? pH=9.00? [OH-]=1.0*10`3M HAS A [H3O+]=?

2007-06-06 10:13:37 · 2 answers · asked by mommy Ty 3

2007-06-06 10:09:41 · 3 answers · asked by Anonymous

I am doing a review for my final and the book does not explain how to answer this problem.
EX:
Molarity=.024 (mol/L) of KOH
Liters= .064 L

2007-06-06 10:01:05 · 3 answers · asked by isthatmatt 4

How many moles of bromine are needed to completely react with 5.4 mol of NaI according to the following reaction.
Br2 + 2NaI --> 2NaBr+I2

How many grams H2O is formed when 32.3g H2 completely reacts with oxygen according to the following equation:
2H2+O2-----> 2H2O

2007-06-06 09:42:30 · 3 answers · asked by Buttons. 1

1. Silver nitrate solution is mixed with a sodium chloride solution.

2. Solid calcium chloride and solid aluminum sulfate react when heated producing calcium sulfate and aluminum chloride.

3.. Aluminum metal reacts with sulfuric acid to produce hydrogen gas and aluminum sulfate.

4. Solid alumninum phosphate reacts with aqueous sodium sulfate

2007-06-06 09:29:33 · 1 answers · asked by Anonymous

I'm using a rust inhibitor on a bearing assembly that I designed and I need to know how the BARIUM SULFONATE based rust inhibitor will react with the Buna-N Rubber (standard rubber O-Ring material).

2007-06-06 09:20:56 · 1 answers · asked by Steve W 1

down's cell with NaCl
7 volts
4 hours
4.0 x 10^(-4) A
how many grams of Na and Cl2 are produced?

2007-06-06 08:52:48 · 1 answers · asked by damageisdone. 1

Mix them by water in that percent :
60 : 15 : 25
but i don't know if it must be hot or cold water.........HELP ME PLZZZZ.......

2007-06-06 08:32:32 · 2 answers · asked by Jack M 3

What is the product(s) of the addition of HF to ethylene?

a.ethane and elemental fluorine
b.1,2-difluoroethane
c.fluoroethylene
d.fluoroethane
e.1,1-difluoroethane

2007-06-06 07:38:26 · 6 answers · asked by Anonymous

Structural isomers are compounds that have

a.the same molar masses, but different elemental composition.
b.two or more double bonds.
c.the same elemental composition, but the atoms are linked in different ways.
d.have identical structures, but contain different isotopes of the same elements.
e.the same elemental composition, but different molar masses

2007-06-06 07:37:50 · 3 answers · asked by Anonymous

Whats the Molecular formula for the following?

cis-4-methyl-1,3-butene

trans-acetylene

trans-2,4-pentadiene

cis-4-methyl-1,3-butadiene

cis-1,3-pentadiene

2007-06-06 07:36:20 · 3 answers · asked by Anonymous