Homework Help: Science: Chemistry

Recent Homework Questions About Chemistry

Chemistry
1) Aldrin and dieldrin are pesticides that used to be allowed for the control of soil insects. In ontario, the maximum allowable total concentration of alrin plus dieldrin in drinking water is 0.7 ppb. If a 250mL sample of drinking water is found to contain 0.0001mg of aldrin ...
Thursday, February 14, 2013 at 6:06am

CHEMISTRY
Ni(NO3)2.H2O+2KSCN WHAT IS THE PRODUCT?? WHAT COMPLEX IS FORMED ?
Thursday, February 14, 2013 at 5:22am

Fundamentals of Chemistry
balance the equation by ion electron method. Fe^++ + MnO4- = Fe3+ +Mn2+ (acidic medium) please help me..!!
Thursday, February 14, 2013 at 3:43am

chemistry
Exactly 50.0ml solution of Na2CO3 was titrated with 65.8ml of 3.00M HCl. If the specific gravity of the Na2CO3 solution is 1.25, what percent by weight of Na2CO3 does it contain?
Thursday, February 14, 2013 at 3:19am

Chemistry
Need help on a lab results write-up. The lab is the synthesis and analysis of a transition metal complex. General reaction was stated as: Fe(III) + x(acac) -> Fe(acac)x - we were to determine x by completing experiment. x = 1, 2, 3, 4... acac = 2, 4 pentanedione Procedure ...
Thursday, February 14, 2013 at 12:14am

Chemistry
Given the following equilibrium constants are given at 377°C, 1/2 N2(g) + 1/2 O2(g) NO(g) K1 = 110−17 1/2 N2(g) + O2(g) NO2(g) K2 = 110−11 N2(g) + 3/2 O2(g) N2O3(g) K3 = 210−33 N2(g) + 2 O2(g) N2O4(g) K4 = 410−17 determine the values for the ...
Wednesday, February 13, 2013 at 11:49pm

Chemistry
At a particular temperature, 13.7 mol of SO3 is placed into a 3.9-L rigid container, and the SO3 dissociates by the reaction given below. 2 SO3(g) 2 SO2(g) + O2(g) At equilibrium, 3.8 mol of SO2 is present. Calculate K for this reaction.
Wednesday, February 13, 2013 at 11:08pm

Chemistry
I am doing a lab on enthaply of vaporization of water, I got everything else on the post lab but these two questions, please help. The deltaHvap data from the handbook reference vary with temp. 1) if your data were perfect, but deltaHvap is not constant, how would this show up...
Wednesday, February 13, 2013 at 10:10pm

Chemistry
How many grams of HCl need to be dissolved in 0.5L of water to prepare a solution of pH 1.5? Does anybody know how to work this out? Thanks :)
Wednesday, February 13, 2013 at 9:07pm

chemistry
A crucible containing potassium chlorate has a mass is 24.426 g. The crucible is heated according to the lab procedure for this week's experiment and is found to weigh 23.202 g. Write an equation for the reaction and, assuming that all the chlorate decomposed, calculate ...
Wednesday, February 13, 2013 at 8:45pm

chemistry
You weigh out 1.70 g of sodium carbonate monohydrate, dissolve it in water and react it with 15.00 mL of 2.00 M HCl. Write an equation for the reaction and calculate the expected mass of carbon dioxide that will be produced.
Wednesday, February 13, 2013 at 7:53pm

Chemistry
A sample of gaseous PCl5 was introduced into an evacuated flask so that the pressure of pure PCl5 would be 0.54 atm at 425 K. However, PCl5 decomposes to gaseous PCl3 and Cl2, and the actual pressure in the flask was found to be 0.85 atm. Calculate Kp for the decomposition ...
Wednesday, February 13, 2013 at 7:09pm

chemistry
2.0 x 10^-5 grams of hydrogen gas at 155 degree calsius exert a pressure of 322.5 torr on the walls of a small cylindrical tube. What is the volume of the tube?
Wednesday, February 13, 2013 at 6:48pm

chemistry
To what temperature, in degree celsius, must 10.0 grams of ammonia gas (NH3) have to be heated in a 15.0 L container in order for it to exert a pressure of 3.50 atm?
Wednesday, February 13, 2013 at 6:46pm

Chemistry
Burning an empty Styrofoam container results in volumes of black sooty flames. On the basis of this observation alone, to what class of hydrocarbons would you suspect a component of the polystyrene polymer found in Styrofoam belongs? Explain.
Wednesday, February 13, 2013 at 6:41pm

chemistry
Calculate the molecular weight of a gas if 4.5L of the gas at 785 torrs and 23.5 degrees celcius weigh 13.5g.
Wednesday, February 13, 2013 at 6:28pm

Chemistry
I did a lab today in class and part of the lab is to experimentally find the enthalpy for the dissolution of ammonium chloride by dissolving 4.0 g of NH4Cl(s) in 50.0 mL of H2O(l). I got a -5°C temperature change and calculated delta H to be 15 kJ/mol. According to the ...
Wednesday, February 13, 2013 at 5:41pm

chemistry
NH4HS(s) <-> NH3(g) + H2S(g) An equilibrium mixture of this reaction at a certain temperature was found to have (NH3)=.268 and (H2S)=.360 What is the value of the equilibrium constant at this temperature?
Wednesday, February 13, 2013 at 5:29pm

CHEMISTRY
Help Please!!!! H2SO4(aq) = 2H+(aq) + SO42-(aq) What is the hydrogen ion concentration, in mol dm−3, when 1.50 g of sulfuric acid is dissolved in water to give 0.500 dm3 of solution
Wednesday, February 13, 2013 at 5:19pm

college chemistry 101
why does an opened bottle of carbonated water keep its frizz longer if kept in a refrigerator than if left at room temperature?
Wednesday, February 13, 2013 at 4:03pm

Chemistry
The solubility of nitrogen in water is 6.9 x 10^-4 at exactly 1 atm pressure. What is the solubility of nitrogen under .80 atmp pressure? I don't know where to start with this problem, what formula do I use?
Wednesday, February 13, 2013 at 3:38pm

Chemistry
The freezing point of ethanol is -114.6 C and its Kf value is 2.00 C/m. What is the freezing point for the solution prepared by dissolving 50.0 g of glycerin (C3H8O3) in 200.0 g ethanol? I used Change in temp=Kfm kf=2.00 I calculated m to be 2.1736. I ended up the answer of -...
Wednesday, February 13, 2013 at 3:34pm

chemistry
what are the fundamental particles in antifreeze
Wednesday, February 13, 2013 at 3:14pm

chemistry
what determines the color of light when an electron moves from one level to another
Wednesday, February 13, 2013 at 3:07pm

chemistry
What volume of a 6.0 M NaOH solution would you need to prepare 250.0 milliliters of a 3.0 M NaOH solution?
Wednesday, February 13, 2013 at 2:40pm

Chemistry
How many milliliters of water has been dispensed if the initial buret reading was 0.38 ml and the final is 24.70 ml
Wednesday, February 13, 2013 at 1:24pm

chemistry
why we cant use hcl to react with Fe to create fecl3?
Wednesday, February 13, 2013 at 1:06pm

Chemistry
What is the osmotic pressure of .100 M solution of aluminum chloride at 27 deg C? I used the formula: pi=(i)(M)(R)(T) wasn't sure what i was but for M put down 0.100M, R=0.08206 and T=300K Answer is 9.85, but not sure how to get that.
Wednesday, February 13, 2013 at 11:59am

Chemistry
The freezing point of ethanol is -114.6 deg Celsius and its Kf value is 2.00degC/m. What is the freezing point for a solution prepared by dissolving 50.0g of glycerin in 200g ethanol? I thought it may have been using the formula deltaT=Kf*m, but I'm not sure.
Wednesday, February 13, 2013 at 11:51am

Chemistry
How many moles of Al(OH) are required to completely react with 2.75mol of H2SO4?
Wednesday, February 13, 2013 at 10:46am

chemistry
determine ox number of each atom below A. CF4 B. KO2 C. SnO D. H2SO4 E. Fe2S3 F. AuCl3
Wednesday, February 13, 2013 at 10:05am

chemistry
Balance using oxidation Number Methode A. MnO4- + C2H4 + H20 --> MnO2 + OH- + C2H6 B. ClO- --> Cl- + ClO3-
Wednesday, February 13, 2013 at 10:03am

chemistry
Balance using oxidation Number Methode A. MnO4- + C2H4 + H20 --> MnO2 + OH- + C2H6 B. ClO- --> Cl- +
Wednesday, February 13, 2013 at 10:01am

chemistry
balance these redox reactants & determine oxidator agent and reducing agent A. Zn + NO3- --> Zn+2 +NH4 + Acid B. Cr(OH)3 + H2O2 --> CrO4 -2 + H20 (Basic)
Wednesday, February 13, 2013 at 9:58am

chemistry
In raction NH3 + 5 O2 --> 4 NO + 6 H20 . I 1 mol NH3 and 1 mol O2. what is the limiting reactant? ow Much NO will form?
Wednesday, February 13, 2013 at 9:54am

chemistry
a sample of iron are is known as Fe3O4. A 50 gram of sample contain 26 gram of Fe. Determine % yield Fe3O4 In sample
Wednesday, February 13, 2013 at 9:51am

chemistry
in reaction = Mg + O2 --> MgO if 24 gram of Mg is burned in excess oxygen to form 40 gram of MgO, How much O2 is used?
Wednesday, February 13, 2013 at 9:49am

chemistry
in reaction S + O2 -> SO2, determine percent yield if 4 grams of S produced 64 gram of SO2
Wednesday, February 13, 2013 at 9:47am

chemistry
in reaction S + O2 -> SO2, determine percent yield if 4 grams of S produced 64 gram of SO2
Wednesday, February 13, 2013 at 9:43am

chemistry
anyone help me . .what volume of concentrated HCL solution whoch is 36% by mass and has a density of 1.179 g/ml , should be used to make 4.7 L of hcl solution with a pH of 1.8 ?
Wednesday, February 13, 2013 at 8:30am

Chemistry
Chromatography relies on the differences in polarity between the compound, the mobile phase and the stationary phase. In your own words explain how polar and non-polar compounds can be separated using cellulose paper and petroleum ether. I have no idea
Wednesday, February 13, 2013 at 7:15am

chemistry
Sulfuric acid is a strong acid and dissociates in water as shown in Reaction 4. Equation label: (4) Help Please!!!! H2SO4(aq) = 2H+(aq) + SO42-(aq) What is the hydrogen ion concentration, in mol dm−3, when 1.50 g of sulfuric acid is dissolved in water to give 0.500 dm3 ...
Wednesday, February 13, 2013 at 7:04am

chemistry
in an attempt to establish the formula of an oxide of nitrogen , a known volume of the pure gas was mixed with hydrogen and passed over a catalyst at a suitable temperature. 100% conversion of the oxide to ammonia and water was shown to have taken place. NxHy gives xNH3 + YH20...
Wednesday, February 13, 2013 at 5:09am

Chemistry
You are asked to prepare a pH = 4.00 buffer starting from 1.50 L of 0.0200 M solution of benzoic acid (C6H5COOH) and some added sodium benzoate salt (C6H5COONa). a) Find the pH of the benzoic acid solution BEFORE adding the salt. b) Use the Henderson-Hasselbalck equation to ...
Wednesday, February 13, 2013 at 12:47am

chemistry
Suppose you have a solution containing both an iron ii salt and an iron iii salt. how would you proceed to identify both Fe 2+ and Fe 3+ in this solution?
Tuesday, February 12, 2013 at 11:02pm

chemistry
enthalpy change^H is +23kJ mol-1 of phosphine (PH3) for the reaction 2P(s)red+3H2(g)---->2PH3(g) a) Calc. entropy change for this reaction. Explain how this information allows you to determine the spontaneity or non-spontaneity of this reaction at any temp (S for PH3 is ...
Tuesday, February 12, 2013 at 10:06pm

chemistry
a gas sample heated in a cylinder uses 650kJ of heat. a piston that compresses this gas does 800kJ of work. What is the change in internal energy, ^E of the gas during this process?
Tuesday, February 12, 2013 at 9:52pm

chemistry
list the following substances in order of increasing molar entropy at 25'c. H2O(l), H2O(g), H2O(s), C(s), Ar (g) Explain your reasoning
Tuesday, February 12, 2013 at 9:44pm

chemistry
the standard free energies of formation of SO2(g) and SO3(g) are -300.4 and -370.4kJ mol-1 respectively. Calculate the value of the equilibrium constant at 25'C for the reaction 2SO2(g)+O2(g)==>2SO3(g)
Tuesday, February 12, 2013 at 9:37pm

Chemistry
Complete and Balance the following equation using the half-reaction method; (MnO4^-) + (CH3OH) --> (Mn^2+) + (HCO2H)
Tuesday, February 12, 2013 at 9:23pm

Chemistry
Complete and Balance the following equation using the half-reaction method; (MnO4^-) + (CH3OH) --> (Mn^2+) + (HCO2H)
Tuesday, February 12, 2013 at 9:20pm

chemistry
Which of the following os a true statement about the periodic table? A. periods form horizonal rows;groups form vertical columns B. groups form horizontal rows;periods form vertical columns C. catagories form horizontal rows;gases form vertical columns D. gases form horizontal...
Tuesday, February 12, 2013 at 8:54pm

chemistry
A granite sample has a density of 2.76 g/cm3. What is the mass of a granite block that measures 3.25 cm x 5.50 cm x 7.00 cm?
Tuesday, February 12, 2013 at 8:26pm

Chemistry
Consider titrating an unknown chloride sample with 0.10 +/- 0.01M AgNO3 and the following data: Initial Buret reading-0.19 +/- 0.02mL Final Buret reading- 9.26 +/- 0.03mL Unknown sample mass- 95.0 +/- 0.2mg Find the weight 5 of Cl- in the sample.
Tuesday, February 12, 2013 at 7:28pm

chemistry
In a household radiator, 1000 g of steam at 100 C condenses. How much heat is released?
Tuesday, February 12, 2013 at 6:52pm

chemistry
12.50g of an unknown compound (i=2) are dissolved in 50.00g of water and this solution freezes at –7.5 degrees C. What is the molar mass of this compound?
Tuesday, February 12, 2013 at 6:46pm

college chemistry
If i have a highly polar mobile phase, what will happen to the non-polar or less polar compounds during chromatography? will they move less up the TLC plate or actually even more because the mobile phase itself is so polar.
Tuesday, February 12, 2013 at 6:45pm

chemistry
The hydrogen gas collected also contains some water vapor. The pressure of this mixture of gases equals the room pressure. find the partial pressure of H2 gas.
Tuesday, February 12, 2013 at 6:40pm

Chemistry
How much heat is necessary to change a 52.0 g sample of water at 33.0 C into steam at 110.0 C?
Tuesday, February 12, 2013 at 6:12pm

Chemistry
How much heat is necessary to change a 52.0 g sample of water at 33.0 C into steam at 110.0 C?
Tuesday, February 12, 2013 at 6:11pm

Chemistry
Is the Conversion of NO2 to HNO3 endo- or exothemic? Calculate the enthalpy and free energy change for the reaction 4NO2 + o2 + 2H2O-----> 4HNO3 in the aqueous phase.
Tuesday, February 12, 2013 at 6:06pm

chemistry
Draw and name the different structural forms of L-fructose that would exist in aqueous solutions
Tuesday, February 12, 2013 at 5:36pm

Chemistry
1.What mass of water could be absorbed from moist air by a 1000.0g sample of a zeolite with the empirical formula Na2Al2Si3O10*2H2O, assuming that the zeolite had been dehydrated first? 2. What mass of Ca2+ could be removed from hard water by a 2000.0g sample of the hydrated ...
Tuesday, February 12, 2013 at 5:23pm

Laboratory (math, chemistry)
Most analytic methods are subject to drift. Describe a system which could be used to determine the rate of drift of an analytic method.
Tuesday, February 12, 2013 at 5:08pm

CHEMISTRY
How many grams of NaNO2 should be dissolved in 500cm3 solution of nitrous acid (HNO2) with concentration of 0.03mol/dm3 if we wish the solution to show a pH of 3.2 Ka = 4.5 * 10^-4 M(NaNO2) = 69 g/mol
Tuesday, February 12, 2013 at 2:36pm

CHEMISTRY
Whats the pH of the solution which can be prepared by mixing same volumes of 0.5% NH4Cl and 0.25% KOH ? (K=1.8 * 10^-5) M(NH4Cl) 53.5 g/mol M(KOH)=56g/mol
Tuesday, February 12, 2013 at 2:36pm

Chemistry
Determine the theoretical field of aspirin for a student who started the experiment with 2.489 g of salicylic acid. Show your work.
Tuesday, February 12, 2013 at 2:35pm

Chemistry Help!
If 100 grams of KClO3 are heated to form KCl and O2 according to the equation KClO3 ¨ KCl + O2 (Hint: You need to balance the equation) a. How many moles of KClO3 reacted? b. How many moles of KCl are formed? c. How many grams of KCl are formed? d. how many moles of ...
Tuesday, February 12, 2013 at 2:24pm

Chemistry
Acetic acid ionizes in water as follows: CH3COOH + H2O CH3COO– + H3O+ Fewer than 1% of ethanoic acid molecules are ionized at any instant. The acetate ion (CH3COO– ) is therefore ____. A.a poor hydrogen-ion acceptor B.a good hydrogen-ion acceptor C.a poor hydrogen-...
Tuesday, February 12, 2013 at 1:23pm

chemistry
What volume of 0.1 M NaOH is required to neutralize 30 mL of 0.1 M HCl?
Tuesday, February 12, 2013 at 12:48pm

Chemistry
Acetic acid ionizes in water as follows: CH3COOH + H2O --> CH3COO– + H3O+ <-- Fewer than 1% of ethanoic acid molecules are ionized at any instant. The acetate ion (CH3COO– ) is therefore ____. A.a poor hydrogen-ion acceptor B.a good hydrogen-ion acceptor C.a ...
Tuesday, February 12, 2013 at 11:06am

Chemistry
A base has a Kb of 2.5 x 10–11. Which of the following statements is true? A.This is a concentrated base. B.This base ionizes slightly in aqueous solution. C.This is a strong base. D.An aqueous solution of this base would be acidic. My answer is D...?
Tuesday, February 12, 2013 at 11:04am

Chemistry
A substance of Ka of 1 x 10^–5 would be classified as a ____. A.strong acid B.weak acid C.strong base D.weak base I think it is B...?
Tuesday, February 12, 2013 at 11:02am

Chemistry
If the hydrogen ion concentration of a solution if 10^–10M, is the solution acidic, alkaline, or neutral? A.acidic B.alkaline C.neutral D.The answer cannot be determined I think it is B..thanks
Tuesday, February 12, 2013 at 8:58am

Chemistry
Which of these solutions is the most basic? [H+] = 1 x 10^–2 M [OH–] = 1 x 10^–4 M [H+] = 1 x 10^–11 M [OH–] = 1 x 10^–13M I think it is C - please explain - I'm guessing and don't really understand..Thanks
Tuesday, February 12, 2013 at 8:56am

chemistry
80g of NaCl are dissolved in 400g H2O. if the vapor pressure of the water is 40 mmHg , what is the vapor pressure of NaCl above the solution?
Tuesday, February 12, 2013 at 6:26am

•Chemistry
How many mole are present in 2.45x10^23 molecules of CH4? ( CH4= 16.05)
Tuesday, February 12, 2013 at 4:17am

chemistry
one mole of an ideal momoatomic gas at s.t.p undergoes isochoric heating at 25 degrees C. Calculate, the pressure, the heat, the workdone, du, dH.
Tuesday, February 12, 2013 at 2:05am

chemistry
For a certain reaction at constant pressure, ∆H = -15kJ, and 22 kJ of expansion work is done on the system. What is ∆U for this process? So I know ∆= ∆U + Work flow If work is being done on the system, shouldn't work flow be positive? So I assumed ...
Tuesday, February 12, 2013 at 1:00am

Chemistry
What is sigma framework?
Monday, February 11, 2013 at 10:46pm

Chemistry
Naphthalene combustion can be used to calibrate the heat capacity of a bomb calorimeter. The heat of combustion of naphthalene is -40.1 kJ/g. When 0.8210 g of naphthalene was burned in a calorimeter containing 1,000. g of water, a temperature rise of 4.21Ã‚Â&...
Monday, February 11, 2013 at 10:41pm

chemistry
The volume of a gas at 23◦C and 0.13 atm is 73 mL. What volume will the same gas sample occupy at standard conditions? Answer in units of mL
Monday, February 11, 2013 at 10:39pm

Chemistry
When you have 250. mL of a 2.80 M solution of HCl, how many moles of HCl do you have
Monday, February 11, 2013 at 9:33pm

chemistry
what is the specific heat of copper if the temperature of a 100g sample of copper is increased by 23C when 886J of heat is added ?
Monday, February 11, 2013 at 9:33pm

chemistry
help please, have no clue how to solve this. (a) you are given a mixture containing two compounds, A and B. both compounds have a solubility of 1g/100mL of solvent at 20 deg C and 16g/100mL of solvent at 100 deg C. The sample is composed of 3.5 g of A and 10 g of B. at 100 deg...
Monday, February 11, 2013 at 8:30pm

chemistry
a student dissolves 80 mg of a crude product in 4.5 mL( the minimum required) of methanol at 25 deg C . She cools the solution in an ice bath and obtains crystals. The crystals are recovered by filtration and rinsed with 0.5 mL of ice-cold methanol. After drying, the weight of...
Monday, February 11, 2013 at 8:19pm

Chemistry
Someone said, "Calculate the total delta H of the reaction and subtract the total delta H of the product from it. If you get a positive value, it radiates heat which means it's exothermic. If it is negative, heat is needed to get a reaction so it is endothermic."...
Monday, February 11, 2013 at 6:54pm

Chemistry
C6H14 + 19/2 O2 -> 6 CO2 + 7H2O delta H = -4163 kJ What mass of hexane is required to produce 1.0E5 kJ of heat by complete combustion? -4163 kJ/mol x mol C6H14 = 1E5/-4163 kJ/mol Mol = 1E5/-4163 kJ/mol Mol = -24 mol I know I can do m=n x MM now, but shouldn't the value ...
Monday, February 11, 2013 at 6:51pm

college chemistry
How will the Rf values be affected if i use a highly polar mobile phase instead of one that has intermediate polarity?
Monday, February 11, 2013 at 4:51pm

Chemistry
CONCENTRATION OF NaClO IN COMMERCIAL BLEACH. Bleach comes as 6%(mass/volume) solution of NaClO. Calculate the Molarity of NaClO in bleach to three significant figures ( you need molar mass of NaClO)
Monday, February 11, 2013 at 4:41pm

chemistry
A 0.10-mol sample of H2(g) and a 0.10-mol sample of Br2(g) are placed in a 2.0-L container. The reaction H2(g) + Br2(g) <----> 2 HBr(g) is then allowed to come to equilibrium. A 0.20 mol sample of HBr is placed into a second 2.0-L sealed container at the same temperature...
Monday, February 11, 2013 at 2:35pm

A2 Chemistry
This question is about the unnecessary production of carbon dioxide Outdoor flames, such as patio heaters and the Olympic flame, contribute to global warming. This is not only due to the heat released, but also due to the carbon dioxide produced from the combustion of ...
Monday, February 11, 2013 at 1:59pm

Chemistry
Which solution is more concentrated? a) 1.0L of 1.0M aqueous solution, or b) 1.0L of 1.0m aqueous solution
Monday, February 11, 2013 at 1:30pm

Chemistry
Determine the boiling point(bp)of 0.44 m Naphthalene, C10H8, in Benzene, C6H6. kb(C6H6)=2.53, bp(C6H6)=80.1
Monday, February 11, 2013 at 12:32pm

Chemistry
Consider 54.0 mL of a solution of weak acid HA (Ka = 1.00 10-6), which has a pH of 4.200. What volume of water must be added to make the pH = 5.500? I found HA for both and then I used C1V1 = C2V2 plugging in the concentrations of HA in C1 and C2 and 0.054 for V1, but I'm ...
Monday, February 11, 2013 at 11:21am

chemistry
what volume of a concentrated HCl solution which is 36% HCl by mass and has a density of 1.179g/ml should be used to make 5.30L of an HCl solution with a pH of 1.8?
Monday, February 11, 2013 at 4:22am

chemistry
a container holds 200 pounds of water or 132 pounds of gasoline. what is the density of gasoline in g/mL? (hint; the density of water was calculated in the early experiment to be 0.962g/mL)
Monday, February 11, 2013 at 4:18am

Chemistry
A solution contains a mixture of pentane and hexane at room temperature. The solution has a vapor pressure of 235 torr. Pure pentane and hexane have vapor pressures of 425 torr and 151 torr, respectively, at room temperature. What is the mole fraction composition of the mixture?
Monday, February 11, 2013 at 2:18am

Chemistry
CHemical equation showing how NH3 behaves as a base when dissolved in water
Monday, February 11, 2013 at 12:19am

Chemistry
HCl (aq) + NaOH (aq) -> NaCl (aq) + H2O (l) Will the neutralisation reaction be endothermic or exothermic? Hint: think about the net ionic equation. So, taking the hint, I got: OH- + H+ -> H2O Not sure how that helps, and now I'm stuck; how would I figure out if this...
Sunday, February 10, 2013 at 11:56pm

Chemistry
Calculate the pH of a water sample from a playa lake in the western US that has the evaporite mineral potassium bicarbonate (KHCO3) at a concentration of 0.009 mol/kg. Assume the water is in equilibrium with the atmosphere (PCO2 = 10-3.4 bar) and the temperature is 25 ̊C...
Sunday, February 10, 2013 at 11:49pm

Chemistry
What would be the pH of a soda water made by saturating pure water with pure CO2 at 1 atm pressure?
Sunday, February 10, 2013 at 11:47pm

Chemistry
Are my answers correct? C6H14 + 19/2 O2 -> 6 CO2 + 7H2O enthalpy change = -4163 kJ a) if 0.537 mol of carbon dioxide is produced in the reaction represented by the equation above, how much heat is released by the reaction? Enthalpy change = 0.537 mol CO2 x -4163kJ/6 mol CO2...
Sunday, February 10, 2013 at 11:33pm

Chemistry
2C2H2 + 5O2 -> 4CO2 + 2H2O + energy What does the equation communicate about the relative energy of the chemical bonds in the reactants and products? The intermolecular bonds of the reactants are weaker than that of the products' because the products' intermolecular...
Sunday, February 10, 2013 at 11:11pm

AP Chemistry
0.015 moles of a compound are dissolved in 18 fl. oz. of water. At what temperature will the solution begin to freeze? The density of water is 1.00g/mL
Sunday, February 10, 2013 at 11:09pm

chemistry
if thermometer is miscalibrated to read 1.0 degree celsius higher than actual temperature over its entire scale how will it affect molar mass of solute?
Sunday, February 10, 2013 at 10:08pm

chemistry
The scientist has an IR spectrometer in her lab. She acquires an IR spectrum of compound X and finds a relatively weak intensity absorption at ~2100 cm-1 and some medium to strong absorptions in the 2850~2960 cm-1 region plus a strong absorption at 3300 cm-1. Identify the type...
Sunday, February 10, 2013 at 9:29pm

Chemistry
Because the mass of the reactants equal to the mass of the product of a reaction, the number of moles will be conserved. -I think this is sometime true but I don't know a way to prove that it sometime true. Anyone got an idea ? Thanks
Sunday, February 10, 2013 at 9:14pm

ap chemistry
Iron pyrite (FeS2) is the form in whichmuch of the sulfur exists in coal. In the combustion of coal, oxygen reacts with iron pyrite to produce iron(III) oxide and sulfur dioxide, which is a major source of air pollution and a substantial contributor to acid rain. What mass of ...
Sunday, February 10, 2013 at 9:07pm

chemistry
Silicon carbide is one of the hardest materials known. It is often known commercially as carborundum. Silicon carbide is used primarily as an abrasive for sandpaper and is manufactured by heating common sand (silicon dioxide, SiO2) with carbon. - What mass of SiC should result...
Sunday, February 10, 2013 at 9:02pm

Chemistry Help
The ΔHvap of a certain compound is 34.68 kJ·mol–1 and its ΔSvap is 93.60 J·mol–1·K–1. What it the boiling point of this compound?
Sunday, February 10, 2013 at 9:00pm

ap chemistry
We drop 37.4 grams of magnesium into 461 mL of a 3 M HCl solution. What is the maximum volume of dry hydrogen that could be produced by this reaction at STP? Mg(s) + 2HCl(aq) ! MgCl2(aq) + H2(g) Answer in units of liters
Sunday, February 10, 2013 at 8:53pm

ap chemistry
We observe that 5 grams of a gaseous com- pound occupies 1526 mL at 49C and 672 torr. What is the molecular weight of the com- pound? Answer in units of g/mo
Sunday, February 10, 2013 at 8:26pm

Chemistry
The first-order rate constant for the decomposition of N2O5, 2N2O5(g) --> 4NO2(g) + O2(g), at 70 degrees C is 6.82 x 10^-3 s^-1. Suppose we start with .0208 mol of N2O5(g) in a volume of 2.2 L. How many minutes will it take for the quantity of N2O5 to drop to .014 mol? I&#...
Sunday, February 10, 2013 at 7:59pm

Chemistry
2. What is pH? A.) the negative logarithm of the hydrogen ion concentration B.) the positive logarithm of the hydrogen ion concentration C.) the negative logarithm of the hydroxide ion concentration D.) the positive logarithm of the hydroxide ion concentration I have no idea ...
Sunday, February 10, 2013 at 7:43pm

Chemistry
Please help me figure out where I went wrong. HNO3 + KOH -> KNO3 + H2O enthalpy change = -53.4 kJ/mol 55.0 mL of 1.30 mol/L solutions of both reactants, at 21.4°C, are mixed in a calorimeter. What is the final temperature of the mixture? Assume the density of both ...
Sunday, February 10, 2013 at 6:55pm

chemistry
A definite amount of NH4cl was boiled with 100ml of 0.8N naoh for complete reaction . After the reaction mixture containing excess of naoh was neutralized with 12.5ml of 0.75N NH2so4. Calculate the amount of NH4cl taken. I want you to explain about 100ml x 0.8N = 80 12.5ml x 0...
Sunday, February 10, 2013 at 6:43pm

chemistry
calculate the dimensions of a cube that contains 22.4L of gas at STP.
Sunday, February 10, 2013 at 6:34pm

Chemistry
Calculate the pH for each of the following cases in the titration of 50.0 mL of 0.200 M HClO(aq) with 0.200 M KOH(aq). The ionization constant for HClO can be found here. A. Before any addition of KOH B. After addition of 25.0 mL of KOH C. After 30.0 mL of KOH D. After 50.0 mL...
Sunday, February 10, 2013 at 5:35pm

Chemistry
Explain the raise of bonding angle in these molecules: HF, H2O, NH3 and CH4
Sunday, February 10, 2013 at 5:28pm

chemistry
HCOOH(aq) <-----> H^+ (aq)+ HCOO^-(aq) The equilibrium constant (Ka) for Reaction 3 at 25 °C is 1.80 × 10−4 mol dm−3. Calculate the equilibrium concentration of hydrogen ions if the concentration of formic acid at equilibrium is 0.00500 mol dm−3
Sunday, February 10, 2013 at 4:43pm

Chemistry
Consider the following equilibrium: NH4Cl(s)--->NH3(g) + HCl(g) Suppose a vessel containing NH4Cl(s), NH3(g) and HCl(g) is at equilibrium. If the volume of vessel is instantaneously doubled while keeping the temp constant when a new equilibrium is reacted, which of the ...
Sunday, February 10, 2013 at 4:32pm

Chemistry
. In Flask A, you reacted 5.10 g Mg with 0.447 mol HCl. In Flask B, you reacted 24.21 g Mg with 0.998 mol HCl. Which ballon will inflate the most?
Sunday, February 10, 2013 at 4:30pm

chemistry
A definite amount of nh4cl was boiled with 100ml of 0.8N naoh for complete reaction. After the reaction, the reactant mixture containing excess of naoh was neutralized with 12.5ml of 0.75N nh2s04. Calculate the amount of nh4cl takedn The answer 3.78g who helps
Sunday, February 10, 2013 at 3:22pm

chemistry
describe how you would prepare 500ml of a solution containing 0.025M sodium acetate and 0.001% w/v starch.
Sunday, February 10, 2013 at 3:08pm

Chemistry
Find the initial concentration of NO2 if the concentration after 2.00 min is 0.113. k = 0.331 1/(M * s) 2 NO2 (g) + N2 (g) --> 2 N2O (g) + O2 (g)
Sunday, February 10, 2013 at 2:33pm

chemistry
If you were asked to convert 25 cg to the unit hg, which of the following would be the first fraction used in the conversion?
Sunday, February 10, 2013 at 1:34pm

chemistry
Which statement is the best example of pseudoscience? Mike joined a group that studies phrenology. C.J. joined a group that studies endangered species. Katarina joined a group that studies herbal remedies. Lee joined a group that studies stars and planets
Sunday, February 10, 2013 at 1:29pm

chemistry
Which of the following is not an example of a science? geology astronomy astrology ecology
Sunday, February 10, 2013 at 1:08pm

chemistry
Which of the following is not an example of a science? geology astronomy astrology ecology
Sunday, February 10, 2013 at 12:56pm

chemistry
In the previous example, how many ml of 0.1M kmn04 are required to react with 30ml of 0.05M h202? the answer 3ml who helps
Sunday, February 10, 2013 at 12:42pm

Chemistry
At 900.0K, the equilibrium comstant (kp) for the following reaction is 0.345 2SO2 (g) + O2 (g) yields 2SO3 (g) At equilibrium the partial pressure of SO2 is 35.0 atm and that of O2 is 15.9 atm. What is the partial pressure of SO3 in atm? 6.20 X 10-4 ( I think it is this one) ...
Sunday, February 10, 2013 at 12:30pm

Chemistry
2NF3(g) yields N2(g) + 3F2(g) When 2.06 mol of NF3 is placed in a 2.00L container and allowed to come to equilibrium at 800K, the mixture is found to contain 0.0227 mol of N2. What is the value of Kp at this temp? 1.91 X 10-3 1.73 X 10-6 (think this is it) 4.43 X 10-7 1.83 X 10-3
Sunday, February 10, 2013 at 12:25pm

chemistry
A definite amount of nh4cl was boiled with 100ml of 0.8N naoh for complete reaction. After the reaction, the reaction mixture containing excess of naoh was neutralized with 12.5ml of 0.75N nh2s04. Calculate the amount of nh4cl taken. The answer 3.78g who helps me
Sunday, February 10, 2013 at 12:21pm

Chemistry
Consider the following equilibrium: PCl3 (g) + Cl2 (g) yields PCl5 (g) delta H= -92KJ The concentration of PCl3 at equilibrium may be increased by: decreasing the temp (think this is it) adding Cl2 to the system the addition of neon the additio of PCl4
Sunday, February 10, 2013 at 12:20pm

chemistry
2KI+Pb(NO3)2=2KNO3+PbI2 suppose a solution containing 1.25g of KI is combined with a solution containing 2.42g Pb(NO3)2 _what mass of the yellow PbI would result what is the limiting reactant How much in grams of the excess reactant was used how much in grams of the excess ...
Sunday, February 10, 2013 at 12:20pm

Chemistry
What happen when the pink stock solution is heated in a water bath?
Sunday, February 10, 2013 at 10:48am

chemistry
20% of HNO3 reacts with 10g of Caco3 by weight then find the quantity of HNO3?
Sunday, February 10, 2013 at 7:59am

Chemistry
What is the vapor pressure of a aqueous solution containing 10 % (by weight) ethylene glycol (62 g/mol) at 25 °C. PH2O = 24.3 torr at 25°C?
Sunday, February 10, 2013 at 6:19am

Chemistry
When 1.150 grams of an unknown nonelectrolyte dissolves in 10.0 grams of water, the solution freezes at -2.16°C. What is the molecular weight of the unknown compound? Kf for water = 1.86°C/m. -2.16 x m/-1.86 = 1.16 1.16/ .010 kg of water= 116 1.150/116= 9.91 g/mol is ...
Sunday, February 10, 2013 at 5:52am

Chemistry
A solution contains 10.0 g pentane, C5H12, 10.0 g hexane, C6H14 and 10.0 g benzene, C6H6. What is the mole fraction of hexane? I figured the equation would be: ___ M Hexane x 10 Divided by 30 =Mole fraction of Hexane?
Sunday, February 10, 2013 at 3:58am

Chemistry
What mass of water must be used to dissolve 20.0 grams of ethanol, C2H5OH, to prepare a 0.0500 molal solution of ethanol?
Sunday, February 10, 2013 at 3:45am

Chemistry
What is the molality of an aqueous solution that is 10.0% ethanol, C2H5OH, by mass?
Sunday, February 10, 2013 at 3:25am

chemistry
an aqueous solution contains 1 mol of S2O3 ions and this reduces 4 mol chlorine molecules.What is the sulphur containing product of this reaction?
Sunday, February 10, 2013 at 1:21am

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