Sunday
April 20, 2014

# Homework Help: Science: Chemistry

Recent Homework Questions About Chemistry

Chemistry
For the titration of hcl versus NaOh, suggest a better indicator than methyl orange. Why is methyl orange not the ideal choice for this application?
Friday, November 1, 2013 at 10:46am

chemistry
If the thyroid test requires 3.2mCi in an "atomic cocktail," how many milliliters are used to prepare the iodine-131 solution?
Friday, November 1, 2013 at 10:12am

chemistry
Which of the following statements describes why ion exchange of 99% SiO2 - 1% B2O3 in a salt bath of molten postassium chloride (KCl) is not an effective way to increase the surface strength of the glass sample? The ion exchange works correctly, however both air-cooling and ...
Friday, November 1, 2013 at 5:32am

chemistry
I am not sure if you have a typo, but for the reaction to be balanced, that should be Nitrous Acid (HNO2) in the reactant side: 3HNO2 -> HNO3 + H2O + 2NO Note that all the species here are neutral (zero charge). Thus the sum of the individual charges of each element ...
Friday, November 1, 2013 at 12:27am

chemistry
the following is a redox reaction. show which element(s) are oxidized and reduced. include how many total electrons are gained or lost by each element. 3HNO---->HNO3+H2O+2NO
Friday, November 1, 2013 at 12:14am

Chemistry
hi, what is the total mass of carbohydrates, fats, and proteins in a serving of eggplant?
Thursday, October 31, 2013 at 2:27pm

Chemistry
I don't agree with a for #1. If it takes 8 eV to make the electron jump from orbit 1 to orbit 2 then the most likely path back is to emit 8 eV to jump back to orbit 1. I don't agree with d for #2 although that statement is correct. However, I think the Bohr model is ...
Thursday, October 31, 2013 at 2:24pm

Chemistry
The correct answer is 2 and 3
Thursday, October 31, 2013 at 2:17pm

chemistry
I would go with the silvery luster.
Thursday, October 31, 2013 at 2:13pm

Chemistry
What mass of sodium benzoate should you add to 150.00 ml of a 0.15M benzoic acid solution to obtain a buffer with a pH of 4.25?
Thursday, October 31, 2013 at 1:45pm

organic chemistry
Which proton gave rise to the peak that appears at 9.31 ppm on the 1H NMR?
Thursday, October 31, 2013 at 1:23pm

Chemistry
hjk
Thursday, October 31, 2013 at 11:50am

chemistry
All these are consequences of the sole valence electron in alkali metals exept............. the metals are soft Good conductors of electricity the silvery luster Good conductor of heat
Thursday, October 31, 2013 at 11:05am

CHEMISTRY
the ans to no3 is a
Thursday, October 31, 2013 at 10:32am

C. NaHCO3 It actually contains 6 atoms. :3
Thursday, October 31, 2013 at 8:57am

Chemistry
An electron jumps from energy level 1 to energy level 2 by absorbing a photon of energy 8 eV. What is the most likely energy of the photon that will be emitted by the electron when it moves back down to energy level 1? 2 ev 4 ev 8 ev 12 ev What is the best description of the ...
Thursday, October 31, 2013 at 1:17am

which of the following molecules does not contain 5 atoms? A. CaCO3 B. Mg(OH)2 C. NaHCO3 D. Fe2O3
Thursday, October 31, 2013 at 12:44am

Chemistry
Individuals living near copper mines sometimes earn extra money by suspending iron objects in the mine wastewater. Based on your experimentation, explain why the iron objects would be suspended in the wastewater.
Thursday, October 31, 2013 at 12:31am

Chemistry
Which of the following statements describes why ion exchange of 99% SiO2 - 1% B2O3 in a salt bath of molten postassium chloride (KCl) is not an effective way to increase the surface strength of the glass sample? The ion exchange works correctly, however both air-cooling and ...
Wednesday, October 30, 2013 at 11:58pm

Chemistry
Ok I thought that before I submitted the question but I thought that seemed too easy! That you so much for your help though :)
Wednesday, October 30, 2013 at 11:08pm

Chemistry
I'm not sure what you mean by "made both equations exactly the same." The second equation is E = 6.626E-34*3E8/95E-9 = 2.0924E-18, then 2.09824E-18 = 2.180E-18*(1/x^2 - 1/25) which isn't the same as the first equation you solved. x^2 = 1.00017E0 so x = 1.000
Wednesday, October 30, 2013 at 11:08pm

Chemistry
You are absolutely right. And I should have notice that too but didn't until just a second before reading your latest post. The first photon sends it from n = 1 to n = 5 and the emission of energy then sends it back to n = 1. The first part of your observation is also ...
Wednesday, October 30, 2013 at 11:04pm

Chemistry
well i got 5 for the first part but I thought that the delta E was the same for both because the wavelengths were pretty much the same, so i got 1 as the final but thats only because that made both of the equations exactly the same
Wednesday, October 30, 2013 at 10:59pm

Chemistry
I ran through the calc quickly (and could have made an error) but I came up with 5 for where the electron was promoted to (from ground state of n = 1 to n = 5) but I did not get 5 for the final resting place. I will look for the error if you want to post your work.
Wednesday, October 30, 2013 at 10:54pm

Chemistry
A ground state hydrogen atom absorbs a photon of light having a wavelength of 94.96 nm. It then gives off a photon having a wavelength of 95 nm. What is the final state of the hydrogen atom? I think I got 5 for an answer, but I am not sure if I did this right or not
Wednesday, October 30, 2013 at 10:37pm

Chemistry
2.2865
Wednesday, October 30, 2013 at 10:05pm

Chemistry
I would increase the amount of network modifier.
Wednesday, October 30, 2013 at 7:43pm

Chemistry
Which of these processes will lower the glass transition temperature of a glass? *Increase the cooling rate *Decrease the cooling rate *Increase amount of network modifier *Decrease amount of network modifier *Quench the glass to cool the surfaces quickly *Decrease the number ...
Wednesday, October 30, 2013 at 7:42pm

Chemistry
See your post below.
Wednesday, October 30, 2013 at 7:06pm

Chemistry
You can talk about the electronegativity (EN) of bonds(each bond in a molecule) but I don't know that there is a total EN for molecules. For PO3, the P atom has EN of 2.1 and O has 3.5, the difference is 1.4. For the H2S molecules, the H-S bond EN difference is 0.4. For ...
Wednesday, October 30, 2013 at 7:05pm

Chemistry
Could you please explain how electronegativity works and how you find the total electronegativity value of PO3 K2O H2S GIVEN: P- 2.1, O-3.5, K- 0.8, H- 2.1, and S- 2.5 Also how to you tell if the compound is ionic, polar covalent, or non polar covalent? Thank you!!!
Wednesday, October 30, 2013 at 6:54pm

Chemistry
O2 and N2 are diatomic molecules and no matter how they are hooked up whatever one atom has as a dipole it will be negated by the other one. CO2 is linear molecule and the O=C partial dipole is canceled by the C=O of the other half. So N2, O2, and CO2 have no dipole moment. ...
Wednesday, October 30, 2013 at 6:47pm

Chemistry
How can you tell that CO2 has a dipole moment while O2, N2, and HCL does not?
Wednesday, October 30, 2013 at 6:23pm

Chemistry
Could you please explain how electronegativity works and how you find the total electronegativity value of PO3 K2O H2S GIVEN: P- 2.1, O-3.5, K- 0.8, H- 2.1, and S- 2.5 Also how to you tell if the compound is ionic, polar covalent, or non polar covalent? Thank you!!!
Wednesday, October 30, 2013 at 6:12pm

Chemistry
wrong the answer is 2 and 3
Wednesday, October 30, 2013 at 5:09pm

chemistry
"I hate chemistry" and "I don't know how to do these" are not expressions that tell me what you don't understand about these. For example, I told you that N2O4 --> was a decomposition. You should know from that that a single molecule (N2O4) ...
Wednesday, October 30, 2013 at 4:23pm

chemistry
I hate chemistry ahhhh :( iono how to do these
Wednesday, October 30, 2013 at 4:09pm

Chemistry
0.8418
Wednesday, October 30, 2013 at 3:58pm

chemistry
http://www.jiskha.com/display.cgi?id=138​3155348
Wednesday, October 30, 2013 at 2:33pm

chemistry
http://www.jiskha.com/display.cgi?id=138​3151400
Wednesday, October 30, 2013 at 2:31pm

chemistry
http://www.jiskha.com/display.cgi?id=138​3151700
Wednesday, October 30, 2013 at 2:30pm

chemistry
It helps us to help you if you use the same screen name. Different names confuse us and you DON'T get a faster answer. Explain what you don't understand about these. 1 is combustion, 2 is single replacement, and 3 is decomposition.
Wednesday, October 30, 2013 at 2:28pm

chemistry
I think a is a poorly worded question. Au is a poor reducing agent; Au(III) ion is a good oxidizing agent. The use of Au in high end stereo units (I have one with Au coated parts) because Au coated contacts resists oxidation by air.
Wednesday, October 30, 2013 at 2:24pm

Chemistry
No, because "Hydrogen, H2(g), is below silver metal in the activity series of the metals."
Wednesday, October 30, 2013 at 2:13pm

chemistry
For the following reaction, identify the substances oxidized, reduced and the oxidizing and reducing agents? 2SO2 + O2 --> 2SO3
Wednesday, October 30, 2013 at 2:01pm

chemistry
N2 + 2O2 -->2 NO2 Suppose 31.25 g of N and 44.0 G of O react A. Calculate the mass of Nitrogen Dioxide formed. B. Which reactant is the limiting reactant? C. Calculate the mass of the excess reactant left after the reaction. D. Find the % yield if 52.3 g of NO2 is produced.
Wednesday, October 30, 2013 at 1:51pm

chemistry
For the following reaction, identify the substances oxidized, reduced and the oxidizing and reducing agents? 2SO2 + O2 --> 2SO3
Wednesday, October 30, 2013 at 1:49pm

chemistry
Balance equation and type of reaction thx! 1. Al(HSO3)3 + O2 ---> 2. Ag + Cu(NO3)2 ---> 3. N2O4 --->
Wednesday, October 30, 2013 at 1:44pm

chemistry
It is observed that when solid copper is added to a solution containing gold ions, the copper dissolves and the gold precipitates. Similarly, almost every other metal will displace gold from solutions of gold salts. a. Do these results mean that the gold ion is an unusually ...
Wednesday, October 30, 2013 at 1:36pm

Chemistry
Hydrogen, H2(g), is below silver metal in the activity series of the metals. Will the following reaction occur or not occur: Ag(s) + H+(aq)  ??? Explain why or why not.
Wednesday, October 30, 2013 at 1:35pm

Chemistry
If you don't know the solubility rules you should learn them now. Here is a simplified set. http://www.files.chem.vt.edu/RVGS/ACT/no​tes/solubility_rules.html
Wednesday, October 30, 2013 at 1:14pm

Chemistry
Cindy, Adam, Stacy et al., we prefer you use the same screen name. It helps us help you faster. Apply the following definitions. Oxidation is the loss of electrons. Reduction is the gain of electrons. The substance oxidized is the reducing agent. The substance reduced is the ...
Wednesday, October 30, 2013 at 1:12pm

chemistry
a & b. mols N2 = grams/molar mass mols O2 = grams/molar mass Using the coefficients in the balanced equation convert mols N2 to mols NO2. Do the same for mols O2 to mols NO2.\ It is likely that the mol values will be different which means one of them is not right. The correct ...
Wednesday, October 30, 2013 at 1:07pm

Chemistry
For the equation give the formula equation, ionic equation, and the net ionic equation after predicting the products and balancing. Using the solubility rules to indicate solid or aqueous each formula. AgNO3 + NaCl
Wednesday, October 30, 2013 at 12:50pm

Chemistry
For the following reaction, identify the substance oxidized, reduced and the oxidizing and reducing agents. 2SO2 + O2 ----> 2SO3
Wednesday, October 30, 2013 at 12:48pm

chemistry
N2 + 2 O2 ---> 2 NO2. Suppose 31.25 g of N and 44.0 g of oxygen react. A. Calculate the mass of Nitrogen dioxide formed. B. Which reactant is the limiting reactant? C. Calculate the mass of the excess reactant left after the reaction. D. Find the % yield if 52.3 g of NO2 is...
Wednesday, October 30, 2013 at 12:43pm

chemistry
n*wavelength = 2d*sin theta. I presume you want n = 1.
Wednesday, October 30, 2013 at 11:57am

chemistry
Use PV = nRT and solve for n = number of mols, then n = grams/molar mass. Remember P must be in atmospheres, R is 0.08206 L*atm/mol*K and T must be in kelvin.
Wednesday, October 30, 2013 at 11:56am

chemistry
Your x-ray lab has a monochromator consisting of a single crystal of nickel cut so that the (111) plane lies in the cube face. At what angle (in degrees) should the cube face be tilted with respect to the incident beam in order to select radiation with a wavelength λ=3....
Wednesday, October 30, 2013 at 11:07am

Chemistry
1- Which of these processes will lower the glass transition temperature of a glass? Increase the cooling rate Decrease the cooling rate Increase amount of network modifier Decrease amount of network modifier Quench the glass to cool the surfaces quickly Decrease the number of ...
Wednesday, October 30, 2013 at 9:07am

chemistry
calculate the molar mass of a liquid if .955grams of its vapors occupy 2.50Liters at 200 Celsius and 45 torr
Wednesday, October 30, 2013 at 6:40am

chemistry
(111) plane wavelengt ambda= 3.091 A lattice constant is alpha = 3.53 A
Wednesday, October 30, 2013 at 2:25am

chemistry
Your x-ray lab has a monochromator consisting of a single crystal of nickel cut so that the plane lies in the cube face. At what angle (in degrees) should the cube face be tilted with respect to the incident beam in order to select radiation with a wavelength ? The lattice ...
Wednesday, October 30, 2013 at 2:23am

medical billing/codeing
the body's ongoing process of regulating its internal environment-electrolyte balance, blood chemistry, temperature, and so on-is called a. excretion b. metabolism c. homeostasis d. peristalsis
Tuesday, October 29, 2013 at 10:18pm

Chemistry
1080 kJ/mol x # mols = 300.6 kJ Solve for # mols, then n = grams/molar mass. You know molar mass and n, solve for grams.
Tuesday, October 29, 2013 at 9:28pm

Chemistry
If the heat of combustion for a specific compound is -1080.0 kJ/mol and its molar mass is 58.29 g/mol, how many grams of this compound must you burn to release 300.60kJ of heat?
Tuesday, October 29, 2013 at 9:09pm

AP Chemistry
See your other posts below.
Tuesday, October 29, 2013 at 8:53pm

AP Chemistry
dG = 0 = dH - TdS. Plug in 40,700 J/mol for dH and 373 for T, solve for dS, and that's for 1 mol. Correct for 3.3 mol.
Tuesday, October 29, 2013 at 8:52pm

AP Chemistry
I would rewrite the equation as H2 + 1/2 O2 ==> H2O dGof = dHof - TdSof You know dGo and dHo and T, solve for dS. That gives you dS for 1 mol H2O from 1 mol H2. You have 4.44g/2 = 2.22 mols dS for 1 mol x 2.22 mol = ?
Tuesday, October 29, 2013 at 8:49pm

AP Chemistry
I would do the following: Calculate dGo for each substance by dGo - dHo - TdS. Use 298 for T and REMEMBER S is in J/mol and dH is in kJ/mol. Then dGorxn = (n*dGo products) - (n*dGo products)
Tuesday, October 29, 2013 at 8:25pm

Chemistry
Why does shielding in organic molecules cause lower solubility in water?
Tuesday, October 29, 2013 at 8:19pm

Chemistry
It is not wrong, correct way to calculate answers thanks DrBob222
Tuesday, October 29, 2013 at 7:38pm

AP Chemistry
Calculate the standard entropy change for the dimerization of NO2: 2NO2(g)→N2O4(g)at 298 K, if S◦ ∆H◦f J/K·mol NO2(g) 240.06 33.18 N2O4(g) 304.29 9.16 Answer in units of J/K·mol
Tuesday, October 29, 2013 at 6:45pm

AP Chemistry
This temperature represents the freezing point of ethanol. (Which means delta G = 0) What is the entropy change for the vaporization of 3.3 mol H2O(ℓ) at 100◦C and 1 atm? ∆H= 40700 J/mol. Answer in units of J/K
Tuesday, October 29, 2013 at 6:41pm

AP Chemistry
Calculate the entropy change when 4.44g of H2 reacts with O2 according to the reaction 2H2(g) + O2(g)→2H2O(ℓ) at 298 K and 1 atm pressure. The stan- dard molar enthalpy of formation of H 2O(ℓ) at 298 K is −285.8 kJ/mol. The corresponding free energy of ...
Tuesday, October 29, 2013 at 6:40pm

AP Chemistry
Calculate ∆G0 for the following reaction. 4XY + 3Z2−→2Z3X2+ 2Y2 Substance ∆H0f S0kJ/mol J/mol·K XY 205.0 75.0 Y2 −82.0 37.0 Z2 −25.0 78.0 Z3X2 −245.0 137.0 Answer in units of kJ/mol
Tuesday, October 29, 2013 at 6:38pm

Chemistry
thanks
Tuesday, October 29, 2013 at 5:59pm

Chemistry
never mind I figured it out!! hydrogen peroxide, so it breaks down to water and O2 and seeing the bubbles proves that the actual reaction occurred
Tuesday, October 29, 2013 at 5:52pm

Chemistry
1- Which of these processes will lower the glass transition temperature of a glass? Increase the cooling rate Decrease the cooling rate Increase amount of network modifier Decrease amount of network modifier Quench the glass to cool the surfaces quickly Decrease the number of ...
Tuesday, October 29, 2013 at 5:42pm

Chemistry
What titration are you doing?
Tuesday, October 29, 2013 at 5:19pm

Chemistry
what is important about oxygen being formed during a titration?? (formed in container after it has been titrated not in the burette)
Tuesday, October 29, 2013 at 5:06pm

Chemistry
Aspirin affects blood platelets.
Tuesday, October 29, 2013 at 4:53pm

Organic Chemistry
- If a substance is soluble in water then it also has a high boiling point High is a relative word; I don't know how to answer this. - If a substance has a high intermolecular force then it also has a high boiling point Same point here - Shorter carbohydrate chains are ...
Tuesday, October 29, 2013 at 4:49pm

Chemistry
name some advantages of using acetaminophen instead of aspirin as an analgesic
Tuesday, October 29, 2013 at 4:47pm

Organic Chemistry
I want to confirm some things on solubility and boiling points(they might be right or wrong): - If a substance is soluble in water then it also has a high boiling point - If a substance has a high intermolecular force then it also has a high boiling point - Shorter ...
Tuesday, October 29, 2013 at 4:27pm

chemistry
(V1/T1) = (V2/T2) Remember T must be in kelvin.
Tuesday, October 29, 2013 at 3:41pm

chemistry
A sample of gas in a balloon has an initial temperature of 25$${\rm \, ^{\circ}C}$$ and a volume of 1670$${\rm L}$$ . If the temperature changes to 82$${\rm \, ^{\circ}C}$$ , and there is no change of pressure or amount of gas, what is the new volume, \(\texttip{V_{\rm 2}}{V_2...
Tuesday, October 29, 2013 at 2:05pm

chemistry
In the following reaction, how many grams of ferrous sulfide (FeS) will produce 0.56 grams of iron (III) oxide (Fe2O3)? 4FeS + 7O2 d 2Fe2O3 + 4SO2
Tuesday, October 29, 2013 at 12:45pm

Ap chemistry
We first write the balanced chemical reaction: 4 Mn + 3 O2 -> 2 Mn2O3 ; ΔH = -962.3 kJ/mol Mn2O3 We then get the number of moles Mn by dividing the given mass by molar mass of Mn. The molar mass of Mn is 54.94 g/mol (get a periodic table and search for it). 6.4 / 54.94...
Tuesday, October 29, 2013 at 12:08pm

chemistry
The reaction is P4 + O2 -> P2O5 Balancing, P4 + 5 O2 -> 2 P2O5
Tuesday, October 29, 2013 at 12:02pm

chemistry
Phosphorus (p4) burns in the air to give diphophorus pentoxide. what is the blance chemical equation for the reaction
Tuesday, October 29, 2013 at 11:29am

Ap chemistry
The standard enthalpy of formation of Mn2O3 is −962.3 kJ/mol. How much heat energy is liberated when 6.4 grams of man- ganese are oxidized by oxygen gas to Mn2O3 at standard state conditions? Answer in units of kJ
Tuesday, October 29, 2013 at 11:20am

Chemistry
HELP
Tuesday, October 29, 2013 at 11:04am

chemistry
Your x-ray lab has a monochromator consisting of a single crystal of nickel cut so that the (111) plane lies in the cube face. At what angle (in degrees) should the cube face be tilted with respect to the incident beam in order to select radiation with a wavelength λ=3....
Tuesday, October 29, 2013 at 10:35am

chemistry
calculate the mass of one mole of lead ii trioxonitrate v PB(NO3)2 If pb=207, N=14, O=16
Tuesday, October 29, 2013 at 10:35am

Chemistry #17
I gave you directions. Follow the directions. Ccal = 3.982 kJ/K and delta T = 0.95. q = Ccal x 0.95 That gives you q in kJ and (q/5) x molar mass KBr = q in kJ/mol.
Tuesday, October 29, 2013 at 1:44am

Chemistry #17
I have no idea!
Tuesday, October 29, 2013 at 12:44am

Chemistry #17
q in kJ = Ccal x delta T dH/g= q/5 dH/mol = (q/5) x (molar mass KBr/mol) = ?
Tuesday, October 29, 2013 at 12:31am

Chemistry #17
When a 5.00g sample of KBr is dissolved in water in a calorimeter that has a total heat capacity of 3.982 kJ-K, the temperature decreases by .210 K. Calculate the molar heat of solution of KBr. =____kJ/mol
Monday, October 28, 2013 at 11:59pm

Chemistry
1 mol acetophenone ==> 1 mol benzoic acid 85 uL = 85E-3 mL mass acetophenone = 85E-3 mL x 1.03 g/mL = ?g acetophenone mols acetophenone = grams/molar mass mols benzoic acid = mols acetophenone g benzoic acid = mols x molar mass and this is the theoretical yield in grams. (0...
Monday, October 28, 2013 at 11:50pm

Pages: <<Prev | 48 | 49 | 50 | 51 | 52 | 53 | 54 | 55 | 56 | 57 | 58 | 59 | 60 | 61 | 62 | Next>>

Search
Members