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April 18, 2014

Homework Help: Science: Chemistry

Recent Homework Questions About Chemistry

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Chemistry
A 108 mL gas sample has a mass of 77.96 mg at a pressure of 1140 mmHg and a temperature of 183 °C. Assume ideal gas behavior and a completely insulated system, and please don’t forget units with your answers. The system is cooled. Calculate the ...
Monday, March 10, 2014 at 11:30am

Chemistry
118.2
Monday, March 10, 2014 at 11:03am

chemistry
0.05naoh in 2and half ml naoh?
Monday, March 10, 2014 at 5:16am

chemistry
4.75 mL
Monday, March 10, 2014 at 3:31am

Chemistry
In a coffee cup calorimeter, 1.60 g of NH4NO3 is mixed with 75.0 g water at an initial temperature of 23.50 ºC. When the salt was completely dissolved, the solution temperature of the calorimeter became 21.80 ºC. Assume the solution’s specific heat capacity is 4...
Monday, March 10, 2014 at 2:45am

Chemistry
the release of 147 kj of heat
Monday, March 10, 2014 at 12:36am

Chemistry Urgent
Calculate the DHof for the following reaction under standard state conditions: 2 Ag2S(s) + 2 H2O(l) ---> 4 Ag(s) + 2 H2S(g) + O2(g) Given the following information: Ag2S(s) ÄHof = -32.6 kJ/mol H2O(l) Ä Hof = -285.83 kJ/mol H2S(g) ÄHof = -20.6 kJ/mol
Sunday, March 9, 2014 at 10:30pm

Chemistry Urgent
Consider the following problem: Target: 2NOCl(g) ? N2(g)+ O2(g)+Cl2 (g) ?Hrxn= ? Steps: 1. 1/2 N2(g) + 1/2 O2(g)? NO(g) ?H= 90.3 kJ 2. NO(g) + 1/2 Cl2(g) ? NOCl(g) ?H= -38.6 kJ As you determine the ¥ÄHrxn value for the target equation above, what must be done to step ...
Sunday, March 9, 2014 at 10:28pm

chemistry
what is the latent heat of silver metal if 55.0 grams of metal liquefies with 47.3J of heat added?
Sunday, March 9, 2014 at 10:28pm

Chemistry
Potassium permanganate (KMnO4) solutions are used for the determination of iron in samples of unknown concentration. As a laboratory assistant, you are supposed to prepare 700. mL of a 0.200 M KMnO4 solution. What mass of KMnO4, in grams, do you need?
Sunday, March 9, 2014 at 10:21pm

Chemistry Urgent
Assuming that kerosene is C11H24, calculate the standard enthalpy change when 1 mole of kerosene burns completely in oxygen, using the data below: ΔH of formation of C11H24(l) = -327 kJ mol ΔH of formation of CO2(g)= -394 kJ mol ΔH of formation of H2O (l)= -286 ...
Sunday, March 9, 2014 at 10:17pm

Chemistry
a)Plated Ni and Ag at 2.98 V b)Plated Ag and Zn at 1.98 V c)2.10/107.868/2*65.38=0.64g zn this is proven
Sunday, March 9, 2014 at 9:59pm

chemistry
if you had 3.00 g in the question 3.00g(mol/g108)(1molZn/2)(65g/mol)= 0.91g
Sunday, March 9, 2014 at 9:55pm

Chemistry?
Please follow directions and type your school subject in the indicated box.
Sunday, March 9, 2014 at 8:11pm

Chemistry
is the I2 gaseous, or solid? If gaseous, it shifts to the right.
Sunday, March 9, 2014 at 8:06pm

Chemistry
How would applying an external pressure on the following equilibrium affects the distribution of iodide between the polar (aqueous) and non polar (varsol) phases? I2+I^- --> I3^-
Sunday, March 9, 2014 at 8:03pm

Chemistry
PV/T is constant So, if we have 2P, we need 2T to hold the ratio. (T, of course is Kelvin)
Sunday, March 9, 2014 at 7:10pm

Chemistry
A mixture of NaCN and NaHSO4 consists of a total of 0.60 mol. When the mixture is dissolved in 1.0 L of water and comes to equilibrium the pH is found to be 9.7.
Sunday, March 9, 2014 at 7:08pm

chemistry
55 grams also. Because according to law of conservation of mass,the mass of the reactant is equal to the mass of the product.
Sunday, March 9, 2014 at 5:21pm

Chemistry
The pressure on a gas at -58 degrees Celcius is doubled, but its volume is held constant. What will the final temperature be in degrees Celsius?
Sunday, March 9, 2014 at 4:08pm

Chemistry
Before a trip from New York to Boston, the pressure in the automobile tire is 2.1 atm at 280 K. At the end of the trip, the pressure gauge reads 1.88 atm. What is the new Celsius temperature of the air inside the tire?(Assume tires with constant volume). This is how I did it: ...
Sunday, March 9, 2014 at 3:37pm

Chemistry
Consider the following problem: Target: 2NOCl(g) ? N2(g)+ O2(g)+Cl2 (g) ?Hrxn= ? Steps: 1. 1/2 N2(g) + 1/2 O2(g)? NO(g) ?H= 90.3 kJ 2. NO(g) + 1/2 Cl2(g) ? NOCl(g) ?H= -38.6 kJ As you determine the ¥ÄHrxn value for the target equation above, what must be done to step ...
Sunday, March 9, 2014 at 3:30pm

chemistry
A sample of hydrogen at 50◦C exerts a pressure of 0.377 atm. The gas is heated to 61◦C at constant volume. What will its new pressure be? how do i find the pressure? i dont understand!!!!!!!!!!!
Sunday, March 9, 2014 at 3:15pm

chemistry
Calculate the DHof for the following reaction under standard state conditions: 2 Ag2S(s) + 2 H2O(l) ---> 4 Ag(s) + 2 H2S(g) + O2(g) Given the following information: Ag2S(s) ÄHof = -32.6 kJ/mol H2O(l) Ä Hof = -285.83 kJ/mol H2S(g) ÄHof = -20.6 kJ/mol
Sunday, March 9, 2014 at 3:10pm

chemistry
Consider the following problem: Target: 2NOCl (g) ¡æ N2 (g) + O2 (g) + Cl2 (g) ¥ÄHrxn= ? Steps: 1. ¨ö N2(g) + ¨ö O2(g) ¡æ NO(g) ¥ÄH= 90.3 kJ 2. NO(g) + ¨ö Cl2(g) ¡æ NOCl(g) ¥Ä H= -38.6 kJ...
Sunday, March 9, 2014 at 3:07pm

Chemistry
How would you precipitate BaCrO4 from a solution of Ba(NO3)2 and K2CrO7?
Sunday, March 9, 2014 at 3:07pm

chemistry
Calculate the DHof for the following reaction under standard state conditions: 2 Ag2S(s) + 2 H2O(l) ---> 4 Ag(s) + 2 H2S(g) + O2(g) Given the following information: Ag2S(s) ÄHof = -32.6 kJ/mol H2O(l) Ä Hof = -285.83 kJ/mol H2S(g) ÄHof = -20.6 kJ/mol
Sunday, March 9, 2014 at 3:05pm

chemistry
Thanks!
Sunday, March 9, 2014 at 3:03pm

chemistry
mols solute = grams/molar mass Then M = mols/L solution.
Sunday, March 9, 2014 at 3:01pm

chemistry
Kp = Kc(RT)^delta n.
Sunday, March 9, 2014 at 3:00pm

chemistry
7.00 grams of sugar (C12H22O11) are dissolved in water to make 1 L of solution. What is the concentration of this solution? Answer in units of M
Sunday, March 9, 2014 at 2:56pm

Chemistry - Le Chatelier's Principle
Thank you Dr.Bob. I got it now.
Sunday, March 9, 2014 at 2:54pm

chemistry
The equilibrium constant, Kp, for the following reaction is 2.74 at 1150 K. Calculate Kc for this reaction at this temperature. 2SO3(g) 2SO2(g) + O2(g)
Sunday, March 9, 2014 at 2:52pm

chemistry
Use PV = nRT and solve for n = number of mols, then n = grams/molar mass. You know n and grams, solve for molar mass.
Sunday, March 9, 2014 at 2:51pm

Chemistry
It might change phases from liquid to gas. If you drive off all of the water you would be left with N2O5 which is where HNO3 comes from in the first place. N2O5 + H2O ==> 2HNO3 ==> H2O + N2O5
Sunday, March 9, 2014 at 2:50pm

Chemistry - Le Chatelier's Principle
I don't know what it is you don't understand. Frankly you seem to understand it very well. You add H3O^+ and the rxn shifts to the right producing more dichromate which is what you want. The equation is already there. That is the initial equation, the intermediate ...
Sunday, March 9, 2014 at 2:47pm

Chemistry - Le Chatelier's Principle
Hi, I have a question regarding the following chemical equilibrium equation: 2CrO4^2- + 2H3O^+ <--> Cr2O7^2- + 3H2O The question is: how would you manipulate the above equation to produce more Cr2O7^2- ions without adding any Chromium based compounds? I understand the ...
Sunday, March 9, 2014 at 1:30pm

Chemistry
what would the product be of HNO3 is heated
Sunday, March 9, 2014 at 1:19pm

chemistry
A sample of gas has a mass of 0.565g . Its volume is 120 mL at a temperature of 80∘C and a pressure of 747 mmHg . what is the molar mass
Sunday, March 9, 2014 at 11:24am

Chemistry
Consider the following problem: Target: 2NOCl (g) ¡æ N2 (g) + O2 (g) + Cl2 (g) ¥ÄHrxn= ? Steps: 1. ¨ö N2(g) + ¨ö O2(g) ¡æ NO(g) ¥ÄH= 90.3 kJ 2. NO(g) + ¨ö Cl2(g) ¡æ NOCl(g) ¥Ä H= -38.6 ...
Sunday, March 9, 2014 at 9:57am

chemistry
Calculate the DHof for the following reaction under standard state conditions: 2 Ag2S(s) + 2 H2O(l) ---> 4 Ag(s) + 2 H2S(g) + O2(g) Given the following information: Ag2S(s) ÄHof = -32.6 kJ/mol H2O(l) Ä Hof = -285.83 kJ/mol H2S(g) ÄHof = -20.6 kJ/mol Question...
Sunday, March 9, 2014 at 9:51am

chemistry
Jawhol Mein Kampf
Sunday, March 9, 2014 at 3:39am

Chemistry
Note the proper way to write copper(II) sulfate with the cap i and not lower case i. mols CuSO4 = grams/molar mass m = mols/kg solvent. I suppose you are to assume the density of H2O is 1.00 g/mL. Then delta T = i*Kf*m where i for CuSO4 = 2. Finally, subtract delta T from zero...
Sunday, March 9, 2014 at 12:20am

Chemistry
What is the freezing point of a solution prepared by adding 264g of copper(ii) sulfate to 4 liters of water? The freezing point constant of water is 1.86°C/m.
Sunday, March 9, 2014 at 12:01am

Chemistry
iaj;ldsk
Saturday, March 8, 2014 at 11:42pm

chemistry
Heat gained by cool water + heat lost by warm water = 0. [mass cool H2O x specific heat H2O x (Tfinal-Tinitial)] + [mass water H2O x specific heat warm H2O x (Tfinal-Tinitial)] = 0 Substitute and solve for T final.
Saturday, March 8, 2014 at 11:36pm

chemistry
Would you believe twice as much as from one mol (and 1 mol is 196.1 kJ IF that is 196.1 kJ for the reaction as written)?
Saturday, March 8, 2014 at 11:33pm

chemistry
I can't decipher the question.
Saturday, March 8, 2014 at 11:30pm

chemistry
This is a limiting reagent (LR) problem. You know that because amounts are given for BOTH reactants. 1. Write and balance the equation. 2. Convert 150 g KBr to mols. mols = grams/molar mass 3. Convert 120 g Cl2 to mols. 4a. Using the coefficients in the balanced equation, ...
Saturday, March 8, 2014 at 11:29pm

chemistry
75.0 g of H2O at 23.0 oC is added to 100.0 g of H2O at 67.5 oC. What is the temperature of the resulting mixture?
Saturday, March 8, 2014 at 11:25pm

chemistry
Consider the following chemical reaction: 2H2O2(L) ¨ 2H2O(L) + O2(g) ƒ¢Hrxn = -196.1 kJ How much heat is released if 2 moles of O2 are produced?
Saturday, March 8, 2014 at 11:24pm

chemistry
d
Saturday, March 8, 2014 at 11:23pm

chemistry
Consider the following problem: Target: 2NOCl (g) ¡æ N2 (g) + O2 (g) + Cl2 (g) ¥ÄHrxn= ? Steps: 1. ¨ö N2(g) + ¨ö O2(g) ¡æ NO(g) ¥ÄH= 90.3 kJ 2. NO(g) + ¨ö Cl2(g) ¡æ NOCl(g) ¥Ä H= -38.6 kJ...
Saturday, March 8, 2014 at 11:23pm

chemistry
Which of the following pairs are both exothermic processes? Question options: a. Evaporation/melting b. Evaporation/freezing c. Condensation/melting d. Condensation/freezing
Saturday, March 8, 2014 at 11:21pm

chemistry
Calculate the DHof for the following reaction under standard state conditions: 2 Ag2S(s) + 2 H2O(l) ---> 4 Ag(s) + 2 H2S(g) + O2(g) Given the following information: Ag2S(s) ÄHof = -32.6 kJ/mol H2O(l) Ä Hof = -285.83 kJ/mol H2S(g) ÄHof = -20.6 kJ/mol
Saturday, March 8, 2014 at 11:19pm

chemistry
What mass of bromine gas will form from the complete reaction of 150 g potassium bromide and 120 g of chlorine
Saturday, March 8, 2014 at 7:57pm

chemistry
5.3L
Saturday, March 8, 2014 at 6:01pm

chemistry
How much 6.0M NaoH must be added to 0.5L of a buffer that is 0.0200M acetic acid and 0.0250M sodium acetate to raise the PH to 5.75
Saturday, March 8, 2014 at 5:50pm

general chemistry
How much 6.0M NaoH must be added to 0.5L of a buffer that is 0.0200M acetic acid and 0.0250M sodium acetate to raise the PH to 5.75
Saturday, March 8, 2014 at 3:47pm

chemistry
I think maybe you better look up the solubility which is normally in grams or mols per liter but 36 grams in 100 grams is much higher than believable by any stretch of the imagination. A liter of fresh water is about a 1000 grams.
Saturday, March 8, 2014 at 2:14pm

chemistry
see other post
Saturday, March 8, 2014 at 2:12pm

chemistry
solubility is in moles or grams solute/mass solvent, not per mass solution
Saturday, March 8, 2014 at 2:12pm

chemistry
%yield = (actual/theoretical)*100 = 75.5% 0.755 = (50/theoretical). So you want to end up with 66.2g so that with 75.5% yield you will get 50.0 g. You can check that when you finish to see that you actually end up with 50.0 grams. NiCl2.6H2O + 6NH3 ==> Ni(NH3)6Cl2 + 6H2O ...
Saturday, March 8, 2014 at 2:08pm

chemistry
A student stated that the solubility of KCl at 20 degrees Celsius was 36 grams of KCl per 100 grams of solution. What is wrong with this statement?
Saturday, March 8, 2014 at 2:05pm

chemistry
A student stated that the solubility of KCL, at 20 degrees Celsius was 36 grams of KCL per 100 grams of solution. What is wrong with this statement?
Saturday, March 8, 2014 at 2:03pm

chemistry
A student is working on a research project. The instructions in the book on how to prepare Ni(NH3)6Cl2 say that the percent yield in this preparation is 75.5 %. If the limiting reagent for the preparation is NiCl2·6H2O, and the student needs 50.0 grams of the Ni(NH3)...
Saturday, March 8, 2014 at 5:08am

CHEMISTRY
Yes, it's endothermic and you're right for the reason, too. The equation tells you that 43.2 kcal is consumed by 1 mol N2 (28g). All you need to do is proportion that out for 50 g. 43.2 kcal x (50/28) = ?
Saturday, March 8, 2014 at 2:09am

CHEMISTRY
Consider the reaction N2+O2-->2NO with Delta H=43.2kcal. When 50.0g of N2 react with an excess of oxygen, how much heat is generated/consumed? I know that this is an endothermic reaction b/c of the + delta H, is there some sort of formula to use here? I have no idea where ...
Saturday, March 8, 2014 at 1:47am

chemistry
Use PV = nRT for He (n = gram/molar mass) and solve for pHe. Do the same for Ne, then add the partial pressures to obtain total pressure. #2 use PV = nRT
Saturday, March 8, 2014 at 1:39am

chemistry
Use PV = nRT and don't forget to change T to kelvin. C + 273 = K.
Saturday, March 8, 2014 at 1:37am

chemistry
I think you made a typo for answer D. Are you sure that isn't 0.0106 By the way, instead of solving a cubic equation you can substitute each of the answers into the expression an see which comes out with K of 6250
Saturday, March 8, 2014 at 1:36am

chemistry
What's the (Cl2) initially. I've used 0 below. ......2NO(g)+ Cl2(g)<-->2NOCl(g) I.....0.1M.....0........1.0M C.....2x +x -2x E.....0.1+2x...x........1-2x Substitute the E line into Kc expression and solve for x. This is a cubic equation.
Saturday, March 8, 2014 at 1:25am

Chemistry
........2NO + O2 ==> 2NO2 I.....0.775.0.789....0 C.......2x....-x.....2x E..0.775-2x.0.789-x..2x Substitute the E line into Kp expression and solve for x then evaluate the individual pressures. I should point out that I did NOT work this problem as concentrations since you ...
Saturday, March 8, 2014 at 12:56am

Chemistry
MO + 2HCl ==> MCl2 + H2O How many mols HCl did you start with? That's 0.1L x 1.00M = 0.1 mol. How much was neutralized by NaOH? That's 0.02102L x 0.1020M = 0.02144 but that was for a 25.0 mL aliquot of thae original. So the ORIGINAL amount of HCl neutralized was 0....
Saturday, March 8, 2014 at 12:49am

Chemistry
1.600g of a metallic oxide of type MO were dissolved in100mL 1.0M HCl. The resulting liquid was made up to 500mL with distilled water. 25.00mL of the solution ,then required 21.02mL of 0.1020 M of NaOH for neutralization. Calculate the mass of the oxide combining with 1 mole ...
Friday, March 7, 2014 at 11:36pm

CHEMISTRY
Thank you so much!
Friday, March 7, 2014 at 11:20pm

Chemistry
2 NO(g) + O2 (g) <==> 2 NO2 (g) Given that Kp=7.96×1012 for the reaction above and the following starting conditions: Initial Concentrations p(NO)=0.775 atm p(NO2)=0.000 atm p(O2)=0.789 atm Determine the equilibrium concentration of NO2.
Friday, March 7, 2014 at 10:59pm

chemistry
Calculate the final temperature of 290mL of water initially at 31∘C upon absorption of 20kJ of heat.
Friday, March 7, 2014 at 10:26pm

chemistry
Hey Guys so I have this problem with ICE tables that is extremely confusing for me so I would love some help on it! At a Certain Temperature, the equilibrium constant for the reaction of NO with Cl2 is 6250. If the initial concentration of NOCl is 1.0M and that of NO 0.10M ...
Friday, March 7, 2014 at 8:09pm

chemistry
Given the following sets of values for three of the gas variables, calculate the unknown. P = ? mm Hg; V = 26.0 mL; n = 0.007826 mol; T = 15.6°C
Friday, March 7, 2014 at 6:41pm

chemistry
Given the following sets of values for three of the gas variables, calculate the unknown. P = ? mm Hg; V = 26.0 mL; n = 0.007826 mol; T = 15.6°C
Friday, March 7, 2014 at 6:40pm

chemistry
If a gaseous mixture is made of 2.37 g of He and 2.73 g of Ne in an evacuated 1.19 L container at 25°C, what will be the partial pressure of each gas and the total pressure in the container?
Friday, March 7, 2014 at 6:14pm

College Chemistry
A four step procedure will work these problems. 1. Write and balance the equation. You have that. 2. Convert what you have (in this case 81.0 g Na) to mols. mol = grams/molar mass = ? 3. Using the coefficients in the balanced equation, convert mols of what you have (Na) to ...
Friday, March 7, 2014 at 5:08pm

College Chemistry
Please help me. I have worked on this for 2 days. I don't understand the ratio of this equation.4Na+O2 to 2Na2O. for question: How many grams of Na2O are produced when 81.ograms of Na reacts?
Friday, March 7, 2014 at 4:59pm

CHEMISTRY
6.724g hydrate -2.964g anhdrous Na2SO4 ---------- 3.760g H2O driven off. Convert to mols. 3.760/18 = ? mols H2O 2.964/molar mass Na2SO4= ? Now find the ratio of the water to 1.00 mol Na2SO4.
Friday, March 7, 2014 at 3:54pm

CHEMISTRY
Convert 6.50 g N to g urea. 6.50 g N x (molar mass urea/2*atomic mass N) = ? g urea.
Friday, March 7, 2014 at 3:50pm

Chemistry
f the sample spattered while heating and some of the solid was lost, how would this affect the experimentally determined number of molecules of water in the hydrate , increase, decrease or no a ffect ? Explain.
Friday, March 7, 2014 at 11:13am

CHEMISTRY
When 6.724 g of one of the hydrates of sodium sulfate (Na2SO4) was heated to drive off its water of hydration, the residue of anhydrous sodium sulfate has a mass of 2.964 g. What is the value of x in the formula for the hydrate, Na2SO4•xH2O?
Friday, March 7, 2014 at 9:50am

CHEMISTRY
A lawn fertilizer is rated as 6.50% nitrogen, meaning 6.50 g of N in 100 g of fertilizer. The nitrogen is present in the form of urea, (NH2)2CO. How many grams of urea are present in 100 g of the fertilizer to supply the rated amount of nitrogen?
Friday, March 7, 2014 at 9:49am

Chemistry
heat=mass*specificheat*dhangeinTemp
Friday, March 7, 2014 at 5:53am

Chemistry
heat=mass*specificheat*deltaTemp solve for specific heat, then compare that value to gold
Friday, March 7, 2014 at 5:53am

Chemistry
A 2.6 g of a substance that looks like gold needed 9.4 J of heat energy to raise its temperature from 20 to 38 ºC. Is the metal pure gold?
Friday, March 7, 2014 at 4:11am

Chemistry
A 3.68 g sample of solid gold is heated from 24 ºC to 34 ºC. How much energy (in joules and calories) is required? Thank you!
Friday, March 7, 2014 at 4:10am

chemistry
q1 to melt ice solid to liquid water at zero C. . q1 = mass ice x heat fusion q2 to warm liquid water from zero to 45 C. q21 = mass H2O x specific heat H2O x (T final-T initial) Total = q1 + q2
Thursday, March 6, 2014 at 11:16pm

Physical Chemistry
bhjbj
Thursday, March 6, 2014 at 10:45pm

chemistry
What is the total energy change if 150.0 grams of ice at 0.0 oC are melted, then the water is warmed to 45.0 oC? Is this process endothermic or exothermic? ƒ´Hf = 6.01 kJ/mol(multiple steps)
Thursday, March 6, 2014 at 10:32pm

chemistry
you're right, I was actually just trying to research it the search bar. Sorry
Thursday, March 6, 2014 at 10:12pm

chemistry
tritium
Thursday, March 6, 2014 at 9:57pm

chemistry
Which of the isotopes of hydrogen is radioactive
Thursday, March 6, 2014 at 9:26pm

chemistry
I thought we did this together about a week ago.
Thursday, March 6, 2014 at 9:09pm

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