Thursday
September 1, 2016

Homework Help: Science: Chemistry

Recent Homework Questions About Chemistry

Chemistry
A solution is 0.10M in aqueous NH3. Calculate (a) the number of moles and (b) the number of grams of NH4Cl that must be added to 500mL of this solution to prepare a buffer solution with pH=9.15. You may neglect the volume change due to addition of solid NH4Cl. Kb=1.8x10^-5. (...
Wednesday, February 17, 2016 by Chen

Chemistry
I've worked through this problem so many times and I keep getting the same thing yet when I submit it, it says its wrong.. Am I missing something? Q:Calcium hydride (solid) reacts with water to form calcium hydroxide (aqueous) and hydrogen gas. Write a balanced chemical ...
Tuesday, February 16, 2016 by Chem: Troubleshooting

Chemistry
NaCl + H2O + CO2 + NH3 ______> NaHCO3 + NH4Cl 1) You dissolve an excess of NaCl in a solution containing 50.0 mL of 4.77 M ammonia. You bubble in an excess of CO2. Calulate the theoretical yield of sodium bicarbonate. I have no idea how to do this, can I know the step by ...
Tuesday, February 16, 2016 by eylow

chemistry
what does the spectrum of hydrogen tell us about its electrons?
Tuesday, February 16, 2016 by Mia

chemistry
why are there only certain colours in an atomic emission spectra?
Tuesday, February 16, 2016 by Emily

chemistry
assuming in the titration of NaCl and AgNO3, a student erroneously carried it out at a low PH,what effect will it be on the result. explain with an ionic equation
Tuesday, February 16, 2016 by Mina

chemistry
a piece of chalkboard dissolvedin acid solution and the solution bubbled vigorously.The gas caused barium hydroxide solution to form a white precipitate.what is the gas given off?what is the white precipitate?write a chemical equation for the formationof the white precipitate.
Tuesday, February 16, 2016 by semisi caucau

chemistry
what is thiosulphate
Tuesday, February 16, 2016 by Timmy

Chemistry
why is chemistry needed
Tuesday, February 16, 2016 by Timmy

Chemistry: stoich
4. Suppose that an excess of propane, C3H8 , burns in 320 g of oxygen, How many moles of water will be formed? C3H8 + 5 O2 --> 3 CO2 + 4 H2O (1 point) 6.02 E 23 moles 1600 moles 4.0 moles 8.0 moles
Tuesday, February 16, 2016 by Hannah

Chemistry
5. How many grams of iron oxide can be produced from 2.50 g of oxygen reacting with iron, according to the following equation? 2 Fe (s) + 3 O2 (g) -->2 Fe2O3(s)
Tuesday, February 16, 2016 by Hannah

Chemistry
5. How many grams of iron oxide can be produced from 2.50 g of oxygen reacting with iron, according to the following equation? 2 Fe (s) + 3 O2 (g) -->2 Fe2O3(s)
Tuesday, February 16, 2016 by Hannah

Chemistry
Describe how you would distinguish between solutions NH4Cl and NaCl using litmus paper
Tuesday, February 16, 2016 by Miracle

Chemistry
how to separate a mixture of iron filings, salt, sand and wood chips.
Tuesday, February 16, 2016 by Jojo

chemistry
A sample of NH4HS(s) is placed in a 2.57 −L flask containing 0.140 mol NH3(g). NH4HS(s)⇌NH3(g)+H2S(g)KP=0.108at25​∘C What will be the total gas pressure when equilibrium is established at 25∘C? any idea on how to solve it like an outline? Thanks
Tuesday, February 16, 2016 by Steve

Chemistry
I have been stuck on this question please help me solve it? The following reaction is used in some self-contained breathing devices as a source of O2(g). 4KO2(s)+2CO2(g)⇌2K2CO3(s)+3O2(g)Kp​=28.5at25∘C Suppose that a sample of CO2(g) is added to an evacuated ...
Tuesday, February 16, 2016 by Steve

Chemistry
How do I determine the value of the reaction 2HI(g) + 2.4 kcal --> H2(g) + i2(g) delta H = a) 2.4 kcal b) -2.4 kcal c) 0.00024 kcal d) -0.00024 kcal
Tuesday, February 16, 2016 by Susan

Chemistry
How do I determine the value of the reaction 2HI(g) + 2.4 kcal --> H2(g) + i2(g) delta H = a) 2.4 kcal b) -2.4 kcal c) 0.00024 kcal d) -0.00024 kcal
Tuesday, February 16, 2016 by Susan

Chemistry, chemical change
N2(g) + 3H2(g) --> 2NH3(g)+ 22,000. ^H = a) 22,000 kcal b)-22,000 kcal c)22 kcal b)-22 kcal
Tuesday, February 16, 2016 by Alana

Chemistry
Assuming ideal behavior, determine the mole fraction of acetone in a solution of acetone and water if the vapor pressure of acetone changed from 750mmHg to 735mmHg.
Monday, February 15, 2016 by Karla

Chemistry
Determine the vapor pressure (in atm) of water in an aqueous solution of 12% by mass ethylene group (antifreeze) if the vapor pressure of pure water at that temperature is 0.095 atmospheres.
Monday, February 15, 2016 by Samantha

Chemistry
A 10.0 L container contains 1.0 L of solution of a gas. Assume [gas]=1.5x10^-4 M in solution when 2 mol of gas remain in gas form. If 1 mol of gas is removed from the gas phase, what will be the new concentration of the gas in solution? What is the value of k?
Monday, February 15, 2016 by Sarah

Chemistry
How many grams of salt can be made from a 5-gram sample of sodium combined with unlimited bromine?
Monday, February 15, 2016 by Anonymous

Science
I'm really bad at Biology and Science in general. Chemistry and Physics will be difficult for me because I'm not good at the Science branch even though I study and work hard for Science/Biology. What can I do to improve?
Monday, February 15, 2016 by Anonymous

chemistry
Iron can be produced by the reduction of iron(III) Oxide by carbon monoxide: Fe2O3 + 3CO -> 2FE +3CO2 a) what maximum mass of CO2 could be produced from the complete reduction of 14.7g of Fe2O3? b) if 8.73g of CO2 gas was actually collected, what percentage yield of the ...
Monday, February 15, 2016 by Emily

chemistry
when 130.4 mL of 0.459 mol/L silver nitrate solution is mixed with 85.23mL of 0.251 mol/L aluminum chloride solution, a precipitate of silver chloride forms. Find the mass of this Precipitate.
Monday, February 15, 2016 by Emma

Chemistry
A 4.00g piece of magnesium is added to 200mL of 1.40 mol/l HC. Identify the limiting reactant, and calculate the mass of hydrogen gas that should be produced
Monday, February 15, 2016 by Jeddediah

chemistry
a solution containing 13.75g of barium hydroxide is to be neutralized with a 0.150 mol/L phosphoric acid solution. what volume of the acid solution will be required?
Monday, February 15, 2016 by Maxine

chemistry
potassium chlorate can be thermally decomposed to oxygen and potassium chloride. calculate the mass of potassium chlorate that must be decomposed by heat to produce 10.0L of oxygen gas at 150 degrees celsius and 150 kPa pressure
Monday, February 15, 2016 by Max

chemistry
what volume of hydrogen gas, measured at STP, will be produced when 16.0g of magnesium reacts completely with an excess of hydrochloric acid
Monday, February 15, 2016 by Mia

Chemistry 1
i need help as quickly as possible because i am taking a summative practice test and this question i don't understand how to work it out. can you please explain? here is the question: Arrange the following in order of increasing oxidation number of the sulfur atoms in ...
Monday, February 15, 2016 by Elizabeth

Chemistry
Can you determine the limiting reactant just by comparing the masses of the reactants in a reaction?
Monday, February 15, 2016 by Anonymous

Chemistry
estimate the heat of vaporization of water if the vapor pressure is 17.54 torr at 20C and 149.4 torr at 60C. R=8.314 J/mole K. I can't remember how to set up the problem. Would someone be able to send me the formula? Thank you
Monday, February 15, 2016 by Emma

Chemistry
Hey there! I have these two questions for my chemistry class, and I am a little confused on how I should go about solving them. If someone could give me the steps necessary to solve these problems I would be most appreciative. 1.) p-Toluenesulfinic acid undergoes a second-...
Sunday, February 14, 2016 by Ka_Chin

Chemistry
Create a balanced equation for the reaction between sodium and bromine. Find how many grams of salt can be made from 5.00 grams of sodium and unlimited bromine. Is it about 39.8 g NaBr2?
Sunday, February 14, 2016 by Anonymous

Chemistry
At what pressure would 0.150 mole of nitrogen gas at -23.0^o C occupy 8.90 L ?
Sunday, February 14, 2016 by Boberto

Chemistry
What Mass Of Copper(i)oxide Is Formed By Burning 10.5g Of Copper(i)sulfide
Sunday, February 14, 2016 by Precious

Chemistry
What is the volume of 2.0 kg of isopropyl alcohol at 20 degrees Celsius? Density at 20 degrees is 0.785g/ml. I got .00255 ml when using 3 sig figs.
Sunday, February 14, 2016 by Kaylee

chemistry
If a solution containing 22.34 g of mercury(II) perchlorate is allowed to react completely with a solution containing 6.256 g of sodium sulfate, how many grams of solid precipitate will be formed?
Sunday, February 14, 2016 by alex

Chemistry
This is a stoichiometry equation. Cu(s) + 4(HNO3)(aq) -> Cu(NO3)2(aq) + 2(NO2)(g)+2(H2O)(l) If you use 6 moles of nitric acid 4(HNO3), how many moles of Copper (II) Nitrate Cu(No3)2 will be produced?
Sunday, February 14, 2016 by Bryce

Chemistry
A solution containing equal masses of glycerol, C3H8O3, and water has a density of 1.10 g/mL. Calculate the molality of glycerol. I got 11.9 m.
Sunday, February 14, 2016 by Student

Chemistry
A first-order reaction has a half-life of 26.4 seconds. How long does it take for the concentration of the reactant in the reaction to fall to one-eighth of its initial value?
Sunday, February 14, 2016 by Student

chemistry
Consider a sample of excited atoms that lie 3.211 × 10–19 J above the ground state. Determine the emission wavelength (in nanometers) of these atoms.
Sunday, February 14, 2016 by Anisha

chemistry
The first ionization energy, E, of a boron atom is 1.33 aJ. What is the wavelength of light, in nm, that is just sufficient to ionize a boron atom? Values for constants can be found here.
Sunday, February 14, 2016 by Bibi

Chemistry
1. Explain why the can collapsed using the Combined Gas Law where T1 is the initial temperature of the air inside the can before the can was inverted and T2 is the temperature of the air inside the can after it was plunged into the ice water. 2. Why did the can need to be ...
Sunday, February 14, 2016 by Kissan

chemistry
Q1) Write down all possible dissociation reactions of the following species: a) Perchloric acid. b) Propanoic acid. c) Ammonium ion. d) Sulfurous acid.
Sunday, February 14, 2016 by hes

Chemistry
calculate kp for the reaction below. PCl3(g) + Cl2(g) ⇌ PCl5(g) How can I calculate it?
Sunday, February 14, 2016 by JPR

Chemistry
A bolt is ordered with a thread of a diameter of 1.25 inches, what is the diameter in millimeters? If the order was mistaken for 1.25 centimeter by how many millimeters would the bolt be in error?
Sunday, February 14, 2016 by Tom

chemistry
Solutioin A is sodiun hydroxide prepared by dissolving 2.0g in 250cm what is molar concentration of sodium hydroxide
Sunday, February 14, 2016 by ruth

chemistry
a) The combustion of an organic compound in the presence of excess oxygen produced a gas , which makes clear lime water turbid. What element can be identified? 
Sunday, February 14, 2016 by angy

Chemistry
1. As the intermolecular forces between molecules increase in magnitude, do you expect each of the following to increase, decrease or remain the same? My answers: Viscosity: increase Boiling point: increase Vapor pressure: decrease Surface tension: increase Heat of ...
Sunday, February 14, 2016 by Student

Chemistry
A solution containing equal masses of glycerol, C3H8O3, and water has a density of 1.10 g/mL. Calculate the molality of glycerol. I got 11.9 m.
Sunday, February 14, 2016 by Student

chemistry
Consider a sample of excited atoms that lie 3.211 × 10–19 J above the ground state. Determine the emission wavelength (in nanometers) of these atoms.
Saturday, February 13, 2016 by Bibi

Chemistry
1. As the intermolecular forces between molecules increase in magnitude, do you expect each of the following to increase, decrease or remain the same? My answers: Viscosity: increase Boiling point: increase Vapor pressure: decrease Surface tension: increase Heat of ...
Saturday, February 13, 2016 by Student

science chemistry
A ground state hydrogen atom absorbs a photon of light having a wavelength of 93.03 nm. It then gives off a photon having a wavelength of 396.9 nm. What is the final state of the hydrogen atom? Values for physical constants can be found here.
Saturday, February 13, 2016 by Anisha

Chemistry
Consider a sample of excited atoms that lie 3.211 × 10–19 J above the ground state. Determine the emission wavelength (in nanometers) of these atoms.
Saturday, February 13, 2016 by Anisha

chemistry
a) The combustion of an organic compound in the presence of excess oxygen produced a gas , which makes clear lime water turbid. What element can be identified?  b) A sample of this compound is treated with hot molten sodium metal, the obtained mixture is dissolved in ...
Saturday, February 13, 2016 by angy

Chemistry-Dr.Bob
The solubility of CO2 in water at 25 degrees Celsius and P CO2= 1 atm is 0.034 mol/L. What is its water solubility under normal atmospheric conditions (in air, carbon dioxide is about 380 ppmv assuming that CO2 obeys Henry's Law?
Saturday, February 13, 2016 by Student

chemistry
a) The combustion of an organic compound in the presence of excess oxygen produced a gas , which makes clear lime water turbid. What element can be identified? b) A sample of this compound is treated with hot molten sodium metal, the obtained mixture is dissolved in water and ...
Saturday, February 13, 2016 by angy

chemistry
the reaction of methane and water is one way to prepare hydrogen for use as a fuel: methanw react with water to from carbonmonoxide and hydrogen if you begin with 995g of methane and 2510g of water, 1.which reactant is the limiting reactant? 2.what is the maximum mass of ...
Saturday, February 13, 2016 by dennis

chemistry
what mass of excess reactant remians when the reaction is completed?
Saturday, February 13, 2016 by dennis

chemistry
volume of 0.5 N sodium hydroxide required to neutralize 20 ml of 0.1 N acetic acid ?
Saturday, February 13, 2016 by gurinder

chemistry
Calculate the vapor pressure over the solution, the amount of vapor pressure is lowered at 25°c and 100°c?
Saturday, February 13, 2016 by sgal

chemistry..
(1) The same quantity of electricity is passed through 2voltameters connected in series, one copper voltmeter with copper electrode in a copper(ii) tetraoxosulphate(vi) solution. The other platinum electrode in a dilute solution of tetraoxosulphate (vi) acid. 500cm³ of ...
Saturday, February 13, 2016 by dannystein

Chemistry- Dr. Bob222
What is the final temperature and state of water when 8.50 kJ of energy is added to 10.0 g of ice at 0 degree Celsius. Helpful information: Cs (ice)= 2.1 J/g•C Heat of vaporization (water)= 40.7kJ/mol Ca (water)= 4.184 J/g•C Heat of fusion (water)= 6.02 kJ/mol Cs (...
Saturday, February 13, 2016 by Anonymous

chemistry
Calculate the number of moles of H2O2 required to produce 0.08 moles of HNO3 by the following reaction. 7 H2O2 + N2H4 2 HNO3 + 8 H2O
Friday, February 12, 2016 by levy

chemistry
(1) The same quantity of electricity is passed through 2voltameters connected in series, one copper voltmeter with copper electrode in a copper(ii) tetraoxosulphate(vi) solution. The other platinum electrode in a dilute solution of tetraoxosulphate (vi) acid. 500cm³ of ...
Friday, February 12, 2016 by dannystein

Chemistry
Consider the following reaction: Al + HBr ---> AlBr3 + H2 . When 4 moles of Al reacts with 3 moles of HBr, how many moles of H2 are formed?
Friday, February 12, 2016 by Lev

Chemistry
What is the final temperature and state of water when 8.50 kJ of energy is added to 10.0 g of ice at 0 degree Celsius. Helpful information: Cs (ice)= 2.1 J/g•C Heat of vaporization (water)= 40.7kJ/mol Ca (water)= 4.184 J/g•C Heat of fusion (water)= 6.02 kJ/mol Cs (...
Friday, February 12, 2016 by Neveah

quant chemistry
A standard solution of Mn2+ was prepared by dissolving 0.250 g of Mn in 10 mL of concentrated HNO3 (measured with a graduated cylinder). The resulting solution was quantitatively transferred to a 100 mL volumetric flask and diluted to volume with distilled water. A 10 mL ...
Friday, February 12, 2016 by John

chemistry
Limestone rock contains solid calcium carbonate that can react with acid to give products. In one experiment, 1.452 g of limestone rock is pulverised and then treated with 25.00 mL of 1.035 M HCl solution. After the reaction is completed, the resulting mixture is still acidic...
Friday, February 12, 2016 by Anonymous

Chemistry
Three isotopes of Neon occur naturally: 20Ne (mass = 19.9924 amu) 21Ne (mass = 20.9938 amu) 22Ne (mass = 21.9914 amu) If the percent abundance of 21Ne is 0.2600, what is the percent abundance of 20Ne? How do I set up for these type of problems. I tried just using two and ...
Friday, February 12, 2016 by Karen

Chemistry
How do you Find the mass (in g) of Carbon in 2.980 g Carbon dioxide? I saw the question asked before but couldn't find a solution.
Friday, February 12, 2016 by Karen

Chemistry
How much energy in kJ is needed to heat 7.0L of water from35 degrees Fahrenheit to boiling point 100 degrees Celsius. If the density of water is 1.0g/cm^3 and the heat capacity of water is Cp= 4.184J/g degrees Celsius
Friday, February 12, 2016 by Rosie

Chemistry
How many grams of ammonia NH3 are necessary to react with 1.2X10^24 molecules of oxygen?
Friday, February 12, 2016 by Hillary

chemistry
A certain gas is present in a 11.0L cylinder at 4.0 atm pressure. If the pressure I increased to 8.0 atm the volume of the gas decreased to 5.5L. Find the two constants Ki, the initial value of K, and the Kf, the final value of k, to verify whether the gas obeys boyles law.
Friday, February 12, 2016 by van

Chemistry
It is known that 1.0 L of nitrogen gas reacts with 3.0 L estequilometricamente gas ...? Edit Hydrogen to form 2.0 L of ammonia gas in the same conditions of pressure and temperature. a)What is the final volume of gas? b)5.0 L of N2 + 9.0 L H2. What final volume?
Friday, February 12, 2016 by Anonymous

chemistry
Determine how much heat (in kilojoules) is evolved or absorbed in the reaction of 1.05 g of Na with H2O: 2Na(s)+2H2O(l) →2NaOH(aq)+H2(g),ΔH∘=&#​8722;368.4 kJ
Thursday, February 11, 2016 by Jay

Chemistry
How many sig figs is 820 g of carbon (which has molar mass 12.01) supposed to have when converted to moles?
Thursday, February 11, 2016 by Anonymous

Chemistry
What is the mass of 5mole of li(li=7)
Thursday, February 11, 2016 by Usman

Chemistry
Aspirin can be prepared in the chemistry laboratory by the reaction of salicylic acid with acetic anhydride. What volume of acetic anhydride is required to produce one killogram of aspirin assuming 100%yield
Thursday, February 11, 2016 by kelvin

chemistry
Draw the structures of the three primary (1°) amines with molecular formula C5H13N that contain five carbon atoms in a continuous chain.
Thursday, February 11, 2016 by Hayley

Chemistry
Explain how the presence of several oxygen atoms in a compound containing an -OH group can make the compound acidic. I don't understand this because according to Arrhenius, bases have OH. And it doesn't apply to either Lewis's acid-base theories, or the Bronsted-...
Thursday, February 11, 2016 by Drew

Chemistry
Draw the structures of the three primary (1°) amines with molecular formula C5H13N that contain five carbon atoms in a continuous chain.
Wednesday, February 10, 2016 by Hayley

chemistry
What are the correct IUPAC names for triisopropylmethane and 2,2-dimethylcyclopentane?
Wednesday, February 10, 2016 by Hayley

Chemistry
2NO + O2 yield 2NO2 Suppose that a particular moment during the reaction nitrogen monoxide (NO) is reacting at the rate of 0.074 M/s -1. At what rate is NO2 being formed?
Wednesday, February 10, 2016 by Taylor

Chemistry 101
If a piece of granite weighing 250.0 grams is heated in boiling water to a temperature of 100 C and then placed in a calorimeter containing 400.00 grams of water, the temperature of the water increases from 20.0 C to 28.5 C. what is the specific heat of Granite?
Wednesday, February 10, 2016 by Lilly

Chemistry
List the grams of bleach solution necessary to provide 0.931g of NaClO(laundry bleach is 8.25% NaClO by weight) and the mL of bleach solution that contains the necessary amount... NaClO=74.442 g/mol. Need 0.931 grams of NaClO. Density of NaClO solution is 1.07 g/ml
Wednesday, February 10, 2016 by Niki

Chemistry
the actual yield of a reaction is 55.2g and the theoretical yield is 61.3g calculate the yield
Wednesday, February 10, 2016 by La Jon

Chemistry
The hydrogen gas is collected over water at 25.0°c. The volume of the gas is 246 ml measured at 760 mmhg. calculate the number of grams of h2 collected (vapor pressure of h2=23.76mmhg)
Wednesday, February 10, 2016 by Jocelyn

Chemistry
A gas has a volume of 500 mL at a temperature of -45.0°C. What volume will the gas occupy at 30.0°C? Show your work. What equation should I use for this one? Sorry but my allergies have me feeling drained. Where should i start on this one?
Tuesday, February 9, 2016 by bubble dragon

Chemistry
concentration of H30+ in 0.0250 moldm-3 aqueous epuation of HCL
Tuesday, February 9, 2016 by Archie

Chemistry
Two fixed charges, -4μC and -5μC, are separated by a certain distance. If the charges are separated by 20cm, what is the magnitude of the electric field halfway between the charges? My textbook says that the formula for electric field is (kq)/r^2. But Since I have ...
Tuesday, February 9, 2016 by Emma

Chemistry
If 1.6045g of anhydrous salt remains after heating 1.9045 g of CuC§¤2¡¤xH2O, determine the number of molecules of water of hydration in the original hydrate
Tuesday, February 9, 2016 by Addison

Chemistry
in a neutralization reaction, dilute tetraoxosulphate (vi) acid completely reacted with sodium hydroxide solution
Tuesday, February 9, 2016 by Archie

Chemistry
the ka value of 0.001moldm-3 solution of a weak acid is 1.6*10-6 calculate the ph and the pka
Tuesday, February 9, 2016 by Archie

chemistry
using the Kw for pure water, show that: pH = pKw - pOH
Tuesday, February 9, 2016 by william

AP CHEMISTRY
The equilibrium constant for the reaction PCl3(g) + Cl2(g) ⇀↽ PCl5(g) is 35000 at 760 ◦C. At equilibrium, the partial pressure of PCl5 was 150 bar and that of PCl3 was 8.12 bar. Calculate the equilibrium partial pressure of Cl2. Answer in units of bar. I got ...
Tuesday, February 9, 2016 by Lou

Chemistry
Calculate the mass of Na2C2O4 needed to react with 30mL of 0.050 M KMnO4. The net ionic equation is: 2MnO4- + 5C2O4-2 + 16H+ —> 2Mn+2 + 10CO2 + 8H2O I don't know where to start or how to end up with sodium oxalate. Thanks!
Tuesday, February 9, 2016 by Wayfinders

Chemistry 101
The mileage for a motorcycle with a fuel tank capacity of 22 liters is 35 miles per gallon. The density of gasoline is 0.74 g/cm^3.(dimensional analysis problem) a). How long a trip, in KM can be made on a full tank of gasoline? b). if the price of gasoline is $1.99 per gallon...
Tuesday, February 9, 2016 by Lilly

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