Wednesday
September 2, 2015

Homework Help: Science: Chemistry

Recent Homework Questions About Chemistry

chemistry
ClO3^-(aq)+3SO3^2- ¡÷ Cl^-(aq)+3SO4^2- 1) If the SO3^2- ion is disaapearing at rate of 0.458 mol/L*s, how fast is the Cl^- ion appearing? 2) if the after 10 minutes of reaction time, 1.09x10^-4 mole of Cl^- ion has been produced, how many moles of SO3^2- ion have ...
Tuesday, September 1, 2015 by Ken

Chemistry
if 75.0 ml of 1.5m sodium hydroxide reacts with 100.0 ml of 2.0m phosphoric acid, to give sodium phosphate and water, how many grams of Na3Po4 may be produced?
Tuesday, September 1, 2015 by Joe

Chemistry
determine the molarity of a solution of silver nitrate prepared by dissolving 5g of silver nitrate in 25.0mL of water
Tuesday, September 1, 2015 by Morgan

Chemistry
Explain why the appearance of the wood flame is yellow whereas the gas flame most often appears blue.
Tuesday, September 1, 2015 by Diana

Chemistry
Is the temperature of a luminous flame greater than that of a non luminous flame? Please explain.
Tuesday, September 1, 2015 by Diana

Chemistry
The meter has been defined as 1,650,763.73 wavelengths of the orange-red line of the emission spectrum of ^86Kr. Calculate the frequency of this radiation. In what proportion of the electromagnetic spectrum does the radiation fall?
Tuesday, September 1, 2015 by Anonymous

Chemistry
Is photosynthesis a reversible reaction?
Tuesday, September 1, 2015 by Stoof

Maths
In a survey of 200 students of a school, it was found that 60% study mathematics, 45% study physics, 35% study chemistry, 20% study mathematics and physics, 15% study physics and chemistry, 25% study chemistry and mathematics and 10% none of these subjects. Find the number of ...
Tuesday, September 1, 2015 by Sabah

Chemistry
Calculate the density of an unknown sample of metal given that a 2.3504 gram sample of metal causes the water level in a graduated cylinder to rise from 33.5 ml to 35.2 ml. Show work
Monday, August 31, 2015 by josh

Chemistry
Suppose that 2.091x10^-18 J is absorbed by the electron of a hydrogen atom in the n=1 energy state. Describe the final energy state of the atom.
Monday, August 31, 2015 by Anonymous

Chemistry
How much energy in joules is required to change the energy state of the H-atom electron from n=2 to n=3? from n=2 to n=4? from n=2 to infinity? Kind of confused on this concept. Could you please explain for me? Thanks
Monday, August 31, 2015 by Anonymous

Quick chemistry help
The primary purpose of the scientific method is to A. Solve problems B. Design experiments C. Make observations D. Publish theories Is it c?
Monday, August 31, 2015 by Hannah

Physical Chemistry
If 5.00 mL of 3% H2O2 is decomposed, how many mL of gas will be produced at 1.01 bar and 25C?
Monday, August 31, 2015 by Michelle

Chemistry
is concrete homogeneous or heterogeneous
Monday, August 31, 2015 by Sam

Chemistry
Determine the freezing point of an aqueous solution containing 10.50 g of magnesium bromide in 200.0 g of water.
Monday, August 31, 2015 by Zac

chemistry
The volume of 0.025M Ca(OH)2 solution which can neutralise 100ml of0.0001M H3PO4
Monday, August 31, 2015 by Arun

CHEMISTRY
A large number of hydrogen atoms have electrons excited to the nh=4.How many possible spectral lines can appear in the emission spectrum as a result of the electron reaching the ground state(n1=1)?Draw a diagram to show all path ways for the de-excitation from nh=4 ton1=1.
Monday, August 31, 2015 by BOIKETLO

chemistry
100g of stea initial at 100 degree celcius is passed through a calorimeter containing 1kg of water at 20 degree celcius. Assuming no heat loose and negligible heat capacity of the calorimeter, calculate the final temperature of the calorimeter and the content. heat of ...
Monday, August 31, 2015 by minenhle

Chemistry
If the H-atom electron in the n=1 state absorbs energy equivalent to 2.178x10^-18 J, what energy state will it occupy?
Sunday, August 30, 2015 by Anonymous

Chemistry
7) 14 carat gold has a purity of 58.3%. How many moles of gold are in 163 grams of 14 carat gold? Answer in units of moles. 8) A 15.9 g sample of iron ore is treated as follows. The iron in the sample is all converted by a series of chemical reactions to Fe2O3. The mass of ...
Sunday, August 30, 2015 by Yasmin

chemistry
if 1.37 moles of Pb(NO3)2 is mixed with 2.56 moles of KI, how many moles of PbI2 are produced?
Sunday, August 30, 2015 by Dave

math , physics, chemistry
sec^4x=11tan^2x+5 than what is the value of tanx
Sunday, August 30, 2015 by vikas

Chemistry
How many atoms are present in 0.3333 mol of CO2? I know I need to use the conversion factor of 6.021x10^23 but do I just multiply that times .3333? =2.007?
Sunday, August 30, 2015 by Jordan

Chemistry
The mineral cassiterite is a compound of tin and oxygen. Chemical analysis of cassiterite shows that the mass percentages of tin, Sn, and oxygen, O, are 78.8% and 21.2%, respectively. Determine the formula of this compound. I found the molar mass and correct equation SnO4. Sn-...
Sunday, August 30, 2015 by Jordan

Chemistry
The velocity of an enzyme catalyzed reaction was 10% of Vmax at 2.0 μM substrate concentration. What was the Km in μM? I know Km=1/2Vmax but I do not know if this is the right equation to use or if I am incorporating the known substrate concentration right? I tried ...
Saturday, August 29, 2015 by RJ

Chemistry
a) Biphenyl, C12H10, is a nonvolatile, nonionizing solute that is soluble in benzene, C6H6. At 25 degrees Celcius, the vapor pressure of pure benzene is 100.84 torr. What is the vapor pressure of a solution made from dissolving 13.8 g of biphenyl in 32 g of benzene? b) Express...
Saturday, August 29, 2015 by Eric

chemistry
vapour density of gas is 11.2 volume occupied by 22.4gms at STP?
Saturday, August 29, 2015 by gori

Chemistry
A syrup is added to an empty container with a mass of 104.70 g . When 0.140 pint of syrup is added, the total mass of the container and syrup is 150.01 g . (1 qt = 2 pt) 0.140 pint= 66.2 mL 150.01g mass container and syrup 104.70g mass empty container -------- 45.31 mass syrup...
Saturday, August 29, 2015 by Ann

chemistry
calculate kole fraction of hcl in solution of hcl contaning 24.8% of hcl by mass
Friday, August 28, 2015 by dipak

CHEMISTRY
Explain the terms, Molar mass and Avogadro's number?
Friday, August 28, 2015 by BARNABAS

Chemistry
What can be said about a substance with a triple point above 1atm 1) The liquid state of the substance cannot exist. 2) The gaseous state at 1 atm pressure cannot be condensed to the solid at the triple point temperature. 3) The melting point of the solid must be greater than ...
Friday, August 28, 2015 by Trinh

chemistry
Calculate the mean speed, using equation 1.13 and 1.17 of (a) He atoms and (b) CH4 molecules at (i) 79 K, (ii) 315K, and (iii) 1500K. Vrms= (2(Ek)/m)^1/2 Vrms= (3RT/M)^1/2 M(He)= 4.0*10^-3 kg/mol M(CH4)= 16.0*10^-3 kg/mol
Friday, August 28, 2015 by help?!?!?

Chemistry
an empty flask as a mass of 123.4 grams. When the flask is filled with water, the mass is 211.6 grams. If 10.0 grams of zinc (d=7.14 g/cm3) are added to the flask filled with water (and the sides of the flask are dried from the displaced water) what is the new mass of the flask?
Thursday, August 27, 2015 by Hannah

chemistry
back again with another analytical Q, the question tells you to prep a 50 mL solution of a 750 ppm iron solution using ammonium iron III oxalate trihydrate (MM: 428.06 as a source of iron. Determine the mass of compound required. I'm assuming you would start with a ...
Thursday, August 27, 2015 by paul

chemistry
How many grams of lithium hydroxide are needed to remove 920 g of carbon dioxide in the air
Thursday, August 27, 2015 by Katherine

Chemistry
A compound is found to contain 50.05 % sulfur and 49.95 % oxygen by mass. What is the simplest (empirical) formula for this compound? They said to assume that it is 100 grams. I found the molar mass. S- 32.06 0-16.00 But now I don't know what to do. Please help. Thank you!
Thursday, August 27, 2015 by Jordan

Chemistry
In chemical analysis, it is often necessary to prepare a solution by diluting a stock solution.Calculate how much of a 5.337M NaOH is needed to make 1.669 liters of a 0.063M sodium hydroxide solution. (Remember to include units.)
Wednesday, August 26, 2015 by Alex

Chemistry
To determine the concentration of 10.31mL of an unknown solution of a monoprotic acid, it is titrated with 0.172M sodium hydroxide. The initial reading on the buret of sodium hydroxide is 2.19mL. The final reading is 13.41mL. What is the concentration of the unknown acid?
Wednesday, August 26, 2015 by Alex

chemistry
A block of metal has a width of 3.2 cm, a length of 17.1 cm, and height of 3.6 cm . Its mass is 1.5 kg . Calculate the density of the metal.
Wednesday, August 26, 2015 by sara

chemistry
Two unlabelled organic samples are believed to contain cyclopropane and propane.By means of one chemical test,show how the two compounds can be distinguished?
Wednesday, August 26, 2015 by kyei

chemistry
Will you please help me write this equation in net ionic form. I2(s)+Na2S2O3(aq)-->Na2S2O4(aq) +NaI(aq)
Tuesday, August 25, 2015 by sydney

Chemistry
What is a good website to practice limiting reagent problems?
Tuesday, August 25, 2015 by Jordan

chemistry
Will you help me use the half reaction method to balance these equations. I need to add water molecules and hydrogen ions in acid solutions. I also need to keep the balanced equations in net ionic form. thanks 1) Cl-(aq) + NO3-(aq) --> ClO-(aq) +NO(g) (in acid solution) 2) ...
Monday, August 24, 2015 by CLO

Chemistry
Can you please help me write the oxidation and reduction half reactions represented in each of these redox equations, and help me write the half reactions in net ionic form if they occur in aqueous solution. 1) PbO(s) + NH3(g) --> N2(g) + H2O(l) + Pb(s) 2) I2(s) + Na2S2O3(...
Monday, August 24, 2015 by sydney

chemistry
1 A metal X that raects with metal Y in a solution of Y but does not react with Z in a solution of Z means that --------------. Metal Y is the least reactive Metal X is the least reactive Metal Z is the least reactive Metal Y and metal Z have equal reactivity 2 Oxidation can ...
Monday, August 24, 2015 by mike

chemistry
1 In the reaction of potassium permanganate and iron salt in acidic medium, how many moles of manganese reacted with iron? 2 moles of Mn with 1 mole of Fe 1 mole of Mn with 5 moles of Fe 1 mole of Mn reacts with 1 mole of Fe 5 moles of Mn reacts with 1 mole 2 Which of the ...
Monday, August 24, 2015 by mikel

chemisrty
1 When chemicals pour on the skin, the laboratory first aid is to ---------------. Apply 1% sodium carbonate Apply 1% boric acid solution Flush the eye with a copious amount of clean lukewarm running water Wash with soap and warm water 2 For cut sustained in the laboratory ...
Monday, August 24, 2015 by mikel

Chemistry
How long will it take for a 18.0-g sample of iodine-131 to decay to leave a total of 2.25 g of the isotope? The half-life of iodine-131 is 8.07 days
Sunday, August 23, 2015 by Jillian

Chemistry
You have 75.0 mL of a 2.50 M solution of Na2CrO4 (aq). You also have 125 mL of a 2.15 M solution of AgNO3 (aq). Calculate the concentration of NO3 when the two solutions are added together.
Saturday, August 22, 2015 by Sarah

chemistry
So im tasked to make an aspirin, could you please help me think of a cute or awesome name for my aspirin?
Saturday, August 22, 2015 by rocelle

Chemistry
A compound contains 84% carbon and 10% hydrogen.find the emperical formula.
Friday, August 21, 2015 by Emperical formula and molecular formula

Chemistry
A compound contains 84% carbon and 10% hydrogen.find the emperical formula.
Friday, August 21, 2015 by Sanni

Chemistry
Experiment 1: A has .20 M, B has .20 M and the initial rate is 2.0*10^-4M/min Experiment 2: A has .20 M, B has .40 M, and the initial rate is 8.0*10^-4M/min Experiment 3: A has .40 M, B has .40 M, and the initial rate is 1.6*10^-3M/min Using the data above, answer the ...
Thursday, August 20, 2015 by Finn

Chemistry
How many grams of product are formed from 2.0 mol of N2 (g) and 8.0 mol of Mg(s)? Show all calculations leading to an answer.
Thursday, August 20, 2015 by Robi

CHEMISTRY URGENT HELP
carbon dioxide is moderately soluble in cold water but is completely boiled out if the water is boiled.Solubility increases rapidly with pressure. How is the above phenomenon used in the production of aerated drinks?
Thursday, August 20, 2015 by clive

The Chemistry of Life Quiz // Just Answers please
Which of the following are considered macromolecules? Select all that apply. (2 points) nitrogen lipids proteins*** carbon*** Which property allows water to stick to glass? (1 point) cohesion**** suspension adhesion solution How many valence electrons does carbon have ...
Thursday, August 20, 2015 by XenaGonzalez

Chemistry
how would the presence of a white solid in a solution effect the solution's absorbance? it made its absorbance higher, but i'm not too sure why
Thursday, August 20, 2015 by Casey

Dimensional Analysis Chemistry
want someone to check if this is right, Q: The concentration of lead in drinking water in a home was found to be 2.1x10-9 M. What is the concentration in ppm? ppb? MM=207.2 g/mol. 1 ppm = 1 mg/L. A: 2.1x10^-9 mol/L x 207.2 g/ 1 mol x 1000 mg / 1 g = 4.35x10^-4 ppm. and that is...
Wednesday, August 19, 2015 by paul

Chemistry
A buffer is made by mixing 100 mL of 0.25 M acetic acid (CH3COOH) and 150 mL of 0.10 M sodium acetate (CH3COONa). Calculate the pH of the solution after 0.5g of solid NaOH is added to the solution (Given Ka (CH3COOH) =1.8 x 10-5)
Wednesday, August 19, 2015 by Jaden

Chemistry
A mixture of C3H8 and C2H2 has a mass of 2.5 g . It is burned in excess O2 to form a mixture of water and carbon dioxide that contains 1.5 times as many moles of CO2 as of water. Find the mass of C2H2 in the original mixture.
Wednesday, August 19, 2015 by Sunny

Chemistry
Predict whether the following reactions would be spontaneous or not under standard conditions or if it's impossible to tell. 2 KClO3(s) + 3 C(s) --> 3CO2(g) + 2KCl(s) Exothermic 2 NO(g) + O2(g) --> 2NO2(g) Exothermic H2(g) + Zn(ClO3)2(s) --> 2HClO3(l) + Zn(s) ...
Tuesday, August 18, 2015 by Finn

Chemistry
Calculate the pH of a potassium phosphate buffer if the pKa of KH2PO4 is 7.2 and the acid-base ratio is 2:1 I took Chemistry 7 years ago and am in a review for a Biochem course I am takin. I do not remember the basics so any help with how to get started or what equations to ...
Tuesday, August 18, 2015 by Liz

chemistry
/Users/Sydneyvanalphen/Desktop/Screen Shot 2015-08-18 at 3.21.30 PM.png hi i need help with this homework problem I don't get how they are getting the answer 75?
Tuesday, August 18, 2015 by sydney

Chemistry
1) A reactions has a delta H of -76 Kj and a delta S of -117 J/K. Is the reaction spontaneous at 298 K? Work: Delta G= -76kJ/mol - 298K(-117J/K/1000) Delta G= -41.134 Spontaneous 2) A reaction has a delta H of 11 kJ and a delta S of 49 J/K. Calculate the delta G at 298 K. Is ...
Tuesday, August 18, 2015 by Finn

Chemistry
During its combustion, ethane combines with oxygen to give carbon dioxide and water. A sample of ethane was burned completely and the water that formed has a mass of 1.61 grams. How many grams of ethane were in the sample?
Tuesday, August 18, 2015 by Margaleta

chemistry
what are the precautions taken while preparing tris(acetylacetonato)-manganese 3 from potassium permanganate and acetylacetone.
Tuesday, August 18, 2015 by elina

chemistry
How can DRY calcium carbonate be prepared from sodium carbonate? Na2Co3 + CaCl2 --- NaCL + CaCo3. but how to get dry calcium carbonate
Monday, August 17, 2015 by clive

chemistry
Ethane burns in limited supply of air to give carbon monoxide. What would be the balanced equation for it?
Monday, August 17, 2015 by Anonymous

chemistry
what is the number of moles of Fe2O3 formed when 5.6liter of O2 reacts with 5.6g of Fe?
Monday, August 17, 2015 by swetha

chemistry
Balance by partial methods P4 + hno3 = h3po4+ no2+h2o
Monday, August 17, 2015 by raman

CHEMISTRY
ARRANGE THE FOLLOWING 0.1 M SOLUTIONS IN ORDER OF INCREASING PH
Monday, August 17, 2015 by Anonymous

Chemistry
Why may the absorbance of a filtrate be higher than it's theoretical concentration?
Sunday, August 16, 2015 by Hannah

Chemistry
I have a problem that says: Copper is an excellent electrical conductor widely used in making electric circuits. In producing a printed circuit board for the electronics industry, a layer of copper is laminated on a plastic board. A circuit pattern is then printed on the board...
Sunday, August 16, 2015 by Kerry

Chemistry H
"When you pulled the steel wool apart, you found that the mass was unchanged. When you heated the steel wool, you found that the mass changed. Explain."
Saturday, August 15, 2015 by Rachel

Chemistry
All Brønsted-Lowry acids A. are aqueous solutions. B. can act as Arrhenius acids. C. donate protons. D. all of the above I got C but could it be D?
Saturday, August 15, 2015 by sydney

Chemistry
How many liters of Carbon Dioxide are formed by burning 6011.0 grams of C3H7OH with excess of oxygen gas and is carried out at 20.00 degrees Celsius, and 1.150 atm of pressure. I know this needs PV=nRT but the burning and excess part is throwing me off. Please help me learn ...
Saturday, August 15, 2015 by Alicia

chemistry
Outline the following synthesis: a) 2 – methyl propene -> 2-methyl-2-propanol. b) 3 –ethylpentene -> carbon dioxide, water and 2-ethylbutanoic acid. c) 2 methyl-2-pentene -> 2-chloro-2-methylpetane and 3-chloro-2-methylpentane d) 1-ethylcyclohexene -> 1-...
Saturday, August 15, 2015 by aiman

Chemistry
We were testing standard solutions of Cu(NO3)2 and a filtrate of Cu(NO3)2 using a spectrophotometer and all of the absorbances recorded were higher than what they were predicted to be. Why might this be?
Friday, August 14, 2015 by Georgia

Chemistry
A buffer solution A. contains approximately equal amounts of a weak acid and its conjugate base. B. increases its properties with an increase in the concentrations of the two buffer components. C. resists changes in pH. D. all of the above I got C is that correct, to is it D? ...
Friday, August 14, 2015 by Syd

Chemistry
The equivalence point of any acid titrated with a base occurs when the A. concentration of the acid and concentration of the titrant are equal. B. mass of the acid and the mass of the titrant are equal. C. pH of the mixture of the acid and titrant is 7.0. D. volume of the acid...
Friday, August 14, 2015 by coco

Chemistry
For the reaction ? Li+? N2 →? Li3N , what is the maximum amount of Li3N which could be formed from 11.79 g of Li and 17.08 g of N2? I got 19.72 g as my final answer and I just want to make sure I am correct. If I am not can you please help me understand this problem?
Friday, August 14, 2015 by Allie

chemistry
write the balanced chemical equation for the reaction that would occur ewhen a base is added to a solution containing H2PO4-/HPO4^2- buffer system can you please help we write this balanced equation. thank you
Friday, August 14, 2015 by coco

chemistry
3-pentanol is heated with sulphuric acid (H2SO4) to become compound M. Compound M is reacted with Br2/ H2O to form Compound N. Outline the reaction step and name the compound M and N
Friday, August 14, 2015 by aiman

Chemistry
in the equation, n = cv, what is the meaning of n? I know that it stands for the number of moles, but I'm not exactly sure what that means. Our teacher wants us to mention Avogradro’s number in our explanation
Friday, August 14, 2015 by Jessica

Chemistry Ap
A sprinter completes the 100 yard dash in 9.30 seconds. How long would it take her to complete 100. meters if she continued at the same speed? 1. 10.2 sec 2. 10.9 sec 3. 10.7 sec 4. 9.30 sec
Thursday, August 13, 2015 by Jai

Chemistry
How many moles of acetic acid are present in 10.00 mL if the concentration is 0.500M HC2H3O2?
Wednesday, August 12, 2015 by Ray

Chemistry
I'm working on a problem that says: A 4.00 gram sample of a mixture of CaO and BaO is placed in a 1.00 L vessel containing Co2 at a pressure of 730 torr and a temperature of 25C. The CO2 reacts with the CaO and BaO forming CaCO3 and BaCO3. When the reaction is complete, ...
Wednesday, August 12, 2015 by Zara

chemistry
Help !determine the emprical formula of a compound w which had 34.2 of iron and 65.8 of chlorine cl35.5 fe56
Wednesday, August 12, 2015 by lol

Chemistry
Can someone explain to me what an intermediate product is and give me and example?
Wednesday, August 12, 2015 by john

chemistry
132gram o2 is required for a combustion of 28 liter mixture of ethane and ethene (at NTP) than find out mole fraction of ethane and ethene in the mixture?
Wednesday, August 12, 2015 by rekha

chemistry
how much grams of cao is produced by oxidation of 1gm of calcium
Wednesday, August 12, 2015 by Aarti

Chemistry
Starting with copper metal, describe how a sample crystals of copper 2 chloride may be prepared in the labaratory
Wednesday, August 12, 2015 by Faith

Chemistry
Explain how you would obtain solid sodium carbonate from a mixture of lead carbonate and sodium carbonate powder
Wednesday, August 12, 2015 by Faith

Organic Chemistry (University)
We're supposed to try and figure out the structure of a compound based off the the following information: δ: 2.4 2H triplet δ: 2.1 3H singlet δ: 1.5 2H triplet δ: 1.3 6H singlet δ: 0.9 3H triplet >δ: 2.4 2H triplet This is probably a CH2 ...
Tuesday, August 11, 2015 by james

Chemistry
Can you please explain to me how you would regulate the pressure to favor the products in the this equilibrium system. MgCO3(s)--><-- MgO(s)+CO2(g)
Tuesday, August 11, 2015 by coco

Chemistry
A buffer solution A. contains approximately equal amounts of a weak acid and its conjugate base. B. increases its properties with an increase in the concentrations of the two buffer components. C. resists changes in pH. D. all of the above This one is D right
Tuesday, August 11, 2015 by Lili

Chemistry
All Brønsted-Lowry acids A. are aqueous solutions. B. can act as Arrhenius acids. C. donate protons. D. all of the above I think it is D, but I also think it is c can you please tell me if either of these answers are right thanks
Tuesday, August 11, 2015 by Lola

Chemistry
All Brønsted-Lowry acids A. are aqueous solutions. B. can act as Arrhenius acids. C. donate protons. D. all of the above I am a little confused. I think it is D, but I'm second guessing myself with C
Tuesday, August 11, 2015 by Lola

Chemistry
Can you please explain to me how you would regulate the pressure to favor the products in the this equilibrium system. MgCO3(s)--><-- MgO(s)+CO2(g) Thank you
Tuesday, August 11, 2015 by Sydney

Chemistry
Can you please explain to me how you would regulate the pressure to favor the products in the this equilibrium system. MgCO3(s)--><-- MgO(s)+CO2(g) Thank you
Tuesday, August 11, 2015 by Sydney

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