Tuesday
December 6, 2016

Homework Help: Science: Chemistry

Recent Homework Questions About Chemistry

chemistry chem check
Two liquids, 'R' and 'S' form an ideal mixture, what is true about the relation between the mole fraction of R in the liquid phase (X_r) and that of the vapor phase (Y_r) for most mole fractions in the range of 0<X_r<1. A)X_r < Y_r B) X_r > Y_r C)...
Monday, December 5, 2016 by Anonymous

Chemistry
Calcium carbonate reacts with HCl according to the following equation: 2HCl(aq)+CaCO3(s)?CaCl2(aq)+H2O(l)+CO2(g​) How many moles of HCl are in 58 mL of 0.13 M HCl? What mass of calcium carbonate is needed for complete reaction with the HCl in (a)?
Monday, December 5, 2016 by hbl

Chemistry
Consider the reaction: Fe2O3+2Al=Al2O3 How many kg of Al2O3 are produced from 25.2 kg of Fe2O3 assuming there is sufficient Al?
Monday, December 5, 2016 by Ilazaya

Chemistry
Consider the reaction: Fe2O3+2Al=Al2O3 How many grams of Al are necessary to make 100.2 grams of Al2O3?
Monday, December 5, 2016 by Ilazaya

Chemistry
Consider the reaction: Fe2O3+2Al=Al2O3 How many grams of Fe2O3 Are necessary ro make 100.2 grams of Al2O3? Step by step please.
Monday, December 5, 2016 by Ilazaya

chemistry
What is the seperation energy ineV for Be3+ in the first excited state in eV?
Monday, December 5, 2016 by Anonymous

Chemistry
If a 30.pL tank of laughing gas contains 2.74 moles of N2O at 25 degrees C, what is the pressure (atm) in the tank?
Monday, December 5, 2016 by Dana

Chemistry
How do orbitals on individual atoms interact and change when covalent bonds form in molecules?
Monday, December 5, 2016 by Laura

Chemistry (equlibrium direction) urgent
Consider the endothermic reaction 2 NO(g) <-> N2(g) + O2(g) -If I decrease the volume of the vessel and increasing the total pressure in the vessel, what direction will the equilibrium will shift? (left/right) (I know that decreasing the volume would shift to produce ...
Sunday, December 4, 2016 by Ray

Chemistry
A recipe calls for 5M of sucrose (C12H22O11) dissolved in 750mL of H2O. Please calculate the total mass (g) of sucrose needed. Show all work.
Sunday, December 4, 2016 by Melissa

chemistry
A major component of gasoline is octane (C8H18). When octane is burned in air it chemically reacts with oxygen (O2) to produce carbon dioxide (CO2) and water (H2O). What mass of oxygen gas is consumed by the reaction of 8.17g of octane?.
Sunday, December 4, 2016 by Dee

chemistry
illustrate how to prepare a 1:3 solution of 0.5 hydrochloric acid
Sunday, December 4, 2016 by Priscilla

Chemistry
A solution is made by dissolving 55g of KCl in enough water to make 1.00 L of solution. Assume that the density of the solution is 1.00 g/mol. Calculate the mass percent, molarity, molality, and mole fraction of KCl.
Sunday, December 4, 2016 by Alivia

chemistry
calculate the mass of butane needed to produce 79.7g of carbon dioxide. express your answer to three significant figures and include the apprppriate units
Sunday, December 4, 2016 by marion

Chemistry
A Starbucks Venti Caramel Macchiato contains about 42.0 grams of sugar. If we assume all the sugar is in the form of sucrose, use your answer from Question 4 to determine how many nutritional calories are produced in burning this quantity of sugar. Give your answer as a ...
Sunday, December 4, 2016 by Cali

Chemistry
Table sugar consists primarily of sucrose, C12H22O11(s). The standard enthalpy of combustion for sucrose is the ?Ho for the reaction: C12H22O11(s) + 12 O2(g) ? 12 CO2(g) + 11 H2O(l) Calculate this ?Ho. Give your answer in units of kJ to five significant figures. Use the ...
Sunday, December 4, 2016 by Cali

Chemistry
Magnesium metal reacts with HCl(aq) according to the equation: Mg(s) + 2 HCl(aq) ? MgCl2(aq) + H2(g) In an experiment to determine the ?H for this reaction, 0.158 g of Mg metal is combined with an excess of HCl to make 100.0 mL of solution in a coffee cup calorimeter. Upon ...
Sunday, December 4, 2016 by Cali

Chemistry
Table sugar consists mostly of sucrose, C12H22O11. The standard enthalpy of combustion for sucrose is the standard state delta H for the reaction: C12H22O11 + 12 O 2 ---> 12 CO2 + 11 H2O Calculate this standard state delta H. Give answer in units of kJ to five significant ...
Saturday, December 3, 2016 by Eli

Chemistry
Mg + 2HCI --> MgCl2 + H2 0.158 g of Mg metal is combined with an excess of HCl to make 100.0 ml of solution in a coffee up calorimeter. The reaction rises from 25.60 C to 32.80 C. Determine delta H for the reaction of one mole of Mg. Units in kJ. 3 significant figures.
Saturday, December 3, 2016 by Eli

chemistry
how many grams of NaOh are needed to make 50 g of Na3PO4 according to the equation: 3NaOH+H3PO4=Na3PO4+3H2O (i'm not sure where to even start for this!)
Saturday, December 3, 2016 by Taylor

Chemistry (molarity) *emergency*
Hi there, maybe dumb question but how would I find the initial concentration of Fe^3+?? In lab, we mixed these reactants into one test tube: -0.50mL of 0.0025M Fe(NO3)3 -0.50mL of 0.0025M KSCN -2.50mL of 0.10M HNO3 The net ionic equation for the experiment is: Fe^3+(aq) + SCN...
Saturday, December 3, 2016 by Ray

chemistry
Fe2+ is oxidized to Fe3+ and CrO4is reduced to Cr3+ using an unknown sample containing Fe2+ and 0.04322M K2CrO4 solution in a redox titration. I first need to balance the formula, but I don't know what to do with the potassium.
Saturday, December 3, 2016 by Jen

chemistry
how many grams of NaOh are needed to make 50 g of Na3PO4 according to the equation: 3NaOH+H3PO4=Na3PO4+3H2O (i'm not sure where to even start for this!)
Saturday, December 3, 2016 by Taylor

chemistry
2C2H6 + 7O2 --> 4CO2 + 6H20 given 7.5 X 10 to the 3rd of C2H6 how many grams of CO2 is emitted the 7.5 x 10 to the third is 7500 what do i do to figure out the rest
Saturday, December 3, 2016 by crystal

chemistry
Nitric acid can be produced by the reaction of gaseous nitrogen dioxide with water. 3 NO2(g) + H2O(?) ?? 2 HNO3(?) + NO(g) If 900 L of NO2 gas react with water, what volume of NO gas will be produced? Assume the gases are measured under the same conditions. Answer in L.
Saturday, December 3, 2016 by Anonymous

Chemistry
What mass of carbon dioxide is produced when 7.5g of methane is completely burnt in air.
Saturday, December 3, 2016 by Cathy

chemistry
What is the mass of 3.22mol of ethane
Saturday, December 3, 2016 by give systematic names NH4Br

chemistry
Arrange the following in the increasing order of boiling point 1.ch3br 2.ch3cl.3.chbr3.4.ch2cl2
Saturday, December 3, 2016 by areena

Chemistry
How would you prepare 2.15 L of a 8.00 M solution from a 12.0 M stock solution?
Friday, December 2, 2016 by wonder

Organic chemistry
How would I draw the structure for (3e,5z)-6-bromo-3-fluoro-3,5-nonadiene? I drew out the main chain of 9 C's, fluoride on 3, double bond between 3 and 4, double bond between 5 and 6, bromide extending out from 6. I understanding E is Trans (priorities opposite) and Z is ...
Friday, December 2, 2016 by Huey

Chemistry
can you help me define a buffer and explain how a buffer
Thursday, December 1, 2016 by renae

chemistry chem check
an ideal mixture contains 0.4 mol of nonvolatile solute and 0.8 mol of volatile solvent. the resulting vapor pressure was 60 mmHg at 300K. What vapor pressure should be reported at 300 K for pure solvent? A) 48 mmHg B) 60 mmHg C) 75 mmHg D) 90 mmHg **Would it be B) 60 mmHg ...
Thursday, December 1, 2016 by Anonymous

chemistry
how much mass of chlorine would be needed to make 73 tonnes of hydrogen chloride
Thursday, December 1, 2016 by musaddiq

Chemistry
8.1g of XSO4.7H2O crystal when heated at 90degree for 15 minutes gave 6.9g of the salt,which gave 4.9g when heated further at 120degree. If X is 72. Calculate the amount of water of crystallization in the intermediate and final salts. [X=72,S=32,O=16,H=1]
Thursday, December 1, 2016 by Banko

Chemistry
How many mL of 0.100 M NaOH are required to neutralize (or titrate) 25.0 mL of 0.15 M H3PO4?
Thursday, December 1, 2016 by Joseph

chemistry
Arrange the following in decreasing order of their massess . a. 2.5 moles of water. b. 3.012×10×24 c. 25 g of water
Thursday, December 1, 2016 by poornendu

SCIENCE-CHEMISTRY
Find the mass (kg) of a metallic block in the form of a cube 30cm on the side,if its density is 5.6kg/L.
Thursday, December 1, 2016 by Ericca

Chemistry
1)A solution prepared by adding 0.400 mol of acetic acid (pKa = 4.74) and 0.400 mol of sodium acetate to 100.0 mL of water. The pH of this buffer solution is initially 4.74. Predict the final pH when 55.0 mL of 1.10 M NaOH is added to solution 2) A solution prepared by adding ...
Thursday, December 1, 2016 by Maya

Chemistry
1)A solution prepared by adding 0.400 mol of acetic acid (pKa = 4.74) and 0.400 mol of sodium acetate to 100.0 mL of water. The pH of this buffer solution is initially 4.74. Predict the final pH when 55.0 mL of 1.10 M NaOH is added to solution 2) A solution prepared by adding ...
Thursday, December 1, 2016 by Maya

Chemistry
When ammonia was reacted to copper(ll)oxide at a high temperature, it will produce nitrogen gas, copper metal and water vapour. an experiment was done with 18.0g of ammonia was reacted with 90.0g of copper(ll)oxide. (a)Write balance chemical equations for this reaction. (b)...
Thursday, December 1, 2016 by Reezyy

chemistry
Derived the equation pH = pKa + Log [base] for a weak acid and its conjugate base, [acid]
Thursday, December 1, 2016 by jenn

chemistry
Tell how you would prepare an acetic acid/acetate buffer solution having apH of 3.79. Ka for acetic acid = 1.85 x 10-5
Thursday, December 1, 2016 by jenn

Chemistry 30
How to find Oxidation Numbers of any component
Thursday, December 1, 2016 by Anonymous

chemistry
9.25% KCl solution is prepared by dissolving enough of the salt to give 100.0 g of solution. What is the mass of water required?
Wednesday, November 30, 2016 by carol

Chemistry
Ch3-ch2-c'ch3,ch2'ch3-ch2-ch3
Wednesday, November 30, 2016 by Ashraf

Chemistry
calculate the volume needed to make 2.20 x 10^2 ml of 0.100M cacl2. what would be the total concentration of the final (Cl-) alone?
Wednesday, November 30, 2016 by Lyn

Science chemistry please help
Determine the number of moles of oxygen in 1 mol of dinitrogen tetraoxide
Wednesday, November 30, 2016 by Farhin

Science chemistry
Determine the number of moles of oxygen in 1 mol of dinitrogen tetraoxide N2O4= N 2×14.01g/mol= 28.02g/mol O 4×16.00g/mol= 64.00g/mol N2O4= 92.02g/mol I can't get the right formula to solve the rest. Please help and thank you
Wednesday, November 30, 2016 by Farhin

Chemistry
Arrange the following from LOWEST to HIGHEST number of particles per L of solution: .1m Na3PO4 .1m C2H5OH .01m CO2 .15m NaCL .2m CaCl2
Wednesday, November 30, 2016 by BCarie

Chemistry
one mole of ethanol releases 326.7 calories of energy during combustion. how many calories kilojoules are released? thank you ! :)
Wednesday, November 30, 2016 by Kenlen Smith

Chemistry
Answer the questions about the following reaction. 4Al(s) + 3O2(g) 2Al2O3 (s) How many molecules of O2 are used in the reaction? How many oxygen atoms are required? How many moles of Al2O3 are formed? What is the mole ratio of Al to O2?
Wednesday, November 30, 2016 by Raven-Sierra

Chemistry
Calculate the equilibrium constant 2SO2(g]+O2(g]?2SO3(g] given equilibrium constant of SO2,O2,SO3 are 0.3m,0.14,1.45 respectively wt happens to the equilibrium constant a) if so2 is added b)if o2 is removed
Wednesday, November 30, 2016 by MANASA

Chemistry
2SO2(g]+O2(g]?2SO3(g] ,4 conditions by which concentration of SO3 can be increased I need the answer for my exam i would be thankful if anyone answered it THANK YOU
Wednesday, November 30, 2016 by MANASA

Chemistry 1
Which shows equilibrium between solute and solvent? I'm stumped. a. 2 M CaCl2 b. 1 g Na2CO3 & 100 mL H2O c. 2 mL methanol & 4 mL hexane d. 1 mL H2O & 3 mL ethanol
Wednesday, November 30, 2016 by Anonymous

Chemistry 1
What theoretical mass of MgO is produced if 0.150 g Mg3N2 is produced by strongly heating a 2.000 g sample of Mg in air?
Wednesday, November 30, 2016 by Jay

Chemistry
A 26.3 gram sample of solid potassium chlorate decomposed and produced 9.45 grams of oxygen gas. What is the percent yield of oxygen?
Wednesday, November 30, 2016 by Anonymous

chemistry
In an adiabatic coffee cup, a 75mL of 1.0M HCl and 50mL of 1.0M HaOH were neutralize. The initial temperature is 22.1 C and the final temperature is 26.3 C. What is the enthalpy? S=4.18g/JC and the heat capacity of the adiabatic coffee
Wednesday, November 30, 2016 by KO

Chemistry
1.Which of the following is most soluble in water and why ? a.Ag2SO4 b.Hg2SO4 c.MnCO3 d.CaSO4 2.PH of which salt is same for 1M and 5M solution both and why? a.HCOONa b.C6H5NH3^+Cl c.NH4CN d. NaCN 3.NH4OH is highly soluble in and why ? a.CuSO4 b.AgNO3 c.NH4Cl d.Both 1&2
Tuesday, November 29, 2016 by Minhoya

Chemistry
Phthalic acid, H2C8H404, is a diprotic acid used in the synthesis of phenolphthalein indicator. Ka1= 1.2x 10^-3, and Ka2 = 3.9 x 10^-6. a) Calculate the hydrongen-ion concentration of a .015 M solution. b) What is the concentration of the C8H4O4^2- ion in the solution?
Tuesday, November 29, 2016 by Crystal

Chemistry
What is the relationship between the energy of a single photon and the energy of a mole of photons? This is very confusing.
Tuesday, November 29, 2016 by Molly C. Davids

chemistry
Write a balanced equation for the reaction of liquid bromine with chlorine gas.
Tuesday, November 29, 2016 by annie

AP Chemistry
The rate constant for the equation, 2C2F4 ? C4F8, is 0.05 M^?1· s^?1. We start with 0.111 mol C2F4 in a 3.00-liter container, with no C4F8 initially present. What will be the concentration of C2F4 after 1.00 hour? Answer in units of M.
Tuesday, November 29, 2016 by David

chemistry
In an adiabatic coffee cup, a 75mL of 1.0M HCl and 50mL of 1.0M HaOH were neutralize. The initial temperature is 22.1 C and the final temperature is 26.3 C. What is the therapy? S=4.18g/JC and the heat capacity of the adiabatic coffee cup is 18.80J/C.
Tuesday, November 29, 2016 by KO

Chemistry
E=hc/lambda How would I rearrange this to be able to solve for the other variables (c or lambda)??????? Please and thank you.
Tuesday, November 29, 2016 by Corin

Chemistry
Based on my percent error (65.8%), would this method of testing for iron be considered a valid means of determining iron content in vitamin pills? Why or why not? I don't understand how to fully answer this question. Since my percent error is high, would it be considered ...
Tuesday, November 29, 2016 by Shelene Ramos`

Chemistry
What size volumetric flask do you need to dilute a 0.150M NaOH to 0.390M if you pipette 1500ml?
Tuesday, November 29, 2016 by Sarah

CHEMISTRY
Why would it be better to use lighter colored lights (like yellow) be used in a spectroscopy experiment, rather than a green colored light? If green is used instead of yellow, would absorbance values be higher or lower? I don't understand :(
Tuesday, November 29, 2016 by Marlene

Chemistry
This question refers to spectroscopy. So why are certain colors used in this experiment? For example, why would a yellow light be used instead of a green light? And if I were to use a green light instead of a yellow light, would absorbance values be higher or lower?
Tuesday, November 29, 2016 by Sammy

Chemistry
When We Balance Equations In Chemical Reaction,we Are Obeying The Law Of
Tuesday, November 29, 2016 by Da Silva

Chemistry
If you do percent error and you come up with about 70% error, would this method of testing be considered valid? Why or why not? I don't understand an actual reason to use.
Tuesday, November 29, 2016 by babarra

Chemistry (Molarity) Help
So there's this prelab assignment we're supposed to complete where we would fill out this table with [FeSCN^2+] in each of the test tubes. I'm not completely sure on how to do this? For example, on the first tube calculate the molarity of [FeSCN^2+] with the data ...
Tuesday, November 29, 2016 by Ray

Chemistry
How do differences in molar absorptivity and cell pathlength change the absorbance of a measurement?
Tuesday, November 29, 2016 by Kiki

Chemistry (Dilution) Help please?
Calculate how to prepare 100.0mL of a 1.25x10^-4 M aqueous solution of Fe(NO3)3(aq) by dilution of stock of 0.0025M Fe(NO3)3(aq) in a 100.0mL volumetric flask? I tried using the m1v1=m2v2 equation but it doesn't look like that equation would work for this problem??
Tuesday, November 29, 2016 by Ray

chemistry
Find the volume of carbondioxide produced when 25grams ofCalcium carbonate was completely burnt
Tuesday, November 29, 2016 by Anonymous

chemistry
Find the volume of carbondioxide produced when 25grams ofCalcium carbonate was completely burnt
Tuesday, November 29, 2016 by Anonymous

Chemistry
2 balloons A and B of volume 600 ml and 1000 ml are taken at temperature 400 K. Max capacity of balloon A and B are 800 and 1200 ml resp. When the temperature is raised which balloon will burst first ?
Tuesday, November 29, 2016 by Minhoya

chemistry
why is the spectrum of hydrogen composed of discrete lines?
Tuesday, November 29, 2016 by sara

Chemistry
Calculate the ph value after of 1ml of 0.01 mol/1hcl solution to 1 liter of distilled water that is initially at ph=7
Tuesday, November 29, 2016 by Abigail

Chemistry
How much water at 10°C can be heated to 40°C by the heat evolved from cooling 300g of water from 80°C to 40°C?
Tuesday, November 29, 2016 by Kiven

Chemistry
What is the pH of a 0.36% by mass HCl?(density=1.0 g/mL)
Tuesday, November 29, 2016 by Kiven

Chemistry
Ammonium nitrate a common fertilizer was used by terrorists in the trgic explosion in oklahoma city in 1995.how many litres of gas at 307oc and 1.00atm are formed by the explosive decomposition of 15kg of ammonium nitrate to nitrogen, oxygen and water vapour Solution 2NH4NO3=...
Tuesday, November 29, 2016 by David

Chemistry
If a box contain 256 water molecules and 1 Na+ ion , then what will be the Molarity of the solution.
Tuesday, November 29, 2016 by Robin Jain

chemistry
Identify the species oxidized, the species reduced, the oxidizing agent and the reducing agent in the following electron transfer reaction. 2Fe3+ + Sn2Fe2+ + Sn2+ species oxidized species reduced oxidizing agent reducing agent As the reaction proceeds, electrons are ...
Tuesday, November 29, 2016 by LaMetria

chemistry
The following information is given for ether, C2H5OC2H5, at 1atm: boiling point = 34.6 °C Hvap(34.6 °C) = 26.5 kJ/mol specific heat liquid = 2.32 J/g°C At a pressure of 1 atm, kJ of heat are needed to vaporize a 41.0 g sample of liquid ether at its normal boiling ...
Tuesday, November 29, 2016 by LaMetria

Chemistry
If the change in temperature of a sugar added solution of water increased its boiling point by 0.6C how many moles of sugar was added to the water?
Monday, November 28, 2016 by Bill

Chemistry
A minimum energy of 151 kJ is required to dissociate a mole of iodine molecules, I2. Calculate the wavelength of radiation that supplies this energy, assuming each bond beaks by absorbing one photon.
Monday, November 28, 2016 by Victor

Chemistry
The maximum number of PbO molecules that can be injected is 3.01 x 10*23 1.) How many moles of PbO can be injected? 2.) What mass of PbO can be injected?
Monday, November 28, 2016 by Nayer

Chemistry
Which of the following gases has the highest average speed at 400K? NO2 OF2 SO2 SF6
Monday, November 28, 2016 by Kanye

Chemistry
At 298 K which is larger rate of effusion or rate of diffusion?
Monday, November 28, 2016 by Kanye

Chemistry
A 5.00-L flask contains nitrogen gas at 25°C and 1.00 atm pressure. What is the final pressure in the flask if an additional 2.00 g of N2 gas is added to the flask and the flask cooled to -55°C?
Monday, November 28, 2016 by Kanye

Chemistry
If 3.42 grams of Al2(SO4)3 are required, what mass of H2SO4 must be present?
Monday, November 28, 2016 by Asia

Chemistry
Write an equation for the oxidation of NH2OH to HNO3 by KBrO3. Balance the reaction equation using the ion-electron method.
Monday, November 28, 2016 by Terry

Chemistry 20
Lab: Determining the Quantity of Vitamin C in Fruit Juice Vitamin C, also called ascorbic acid, is commonly found in commercial fruit juices and drinks. In this activity you will analyze data collected from a titration analysis of a fruit juice. The nutrition facts for a 200-...
Monday, November 28, 2016 by Sadie

Chemistry
If you try to carry out a double displacement reaction by mixing together equal volumes of a solution that contains dissolved NaF and a solution that contains dissolved NaCl. Would you expect a reaction? Why or why not?
Monday, November 28, 2016 by Rebecca

Chemistry
Hi, wondering if anyone can help with the following problem: A solution of NH3 (kb=1.8x10^-5) has a ph of 11. what is the molar concentration of NAOH? I am unsure how to go about this however i have tried [10^-3][10^-11]/ 1.8x10^-5 with no success. Thanks for your help
Monday, November 28, 2016 by Frank

chemistry
Calculate the formula of a compound which has composition. MaMagnesium 9.8%,sulphur 13%, oxygen 26%,water of crystallization 51%. (Mg=24,S=32,O=16,H2O=18g/mol)
Monday, November 28, 2016 by furry

Chemistry
Why we add HCL ot H2SO4 during the experiment Of iodometry?
Monday, November 28, 2016 by Mikel

chemistry
A bottle of cabernet sauvignon wine contains 12.5% v/v ethanol. How much ethanol will be present in a dozen 750 mL bottles of this wine?
Sunday, November 27, 2016 by r

Chemistry
I am trying to answer the question below, and I am guessing the reason lactate has a lower Km is that it is better able to accept electrons than ethanol. Is this correct? If so, what makes lactate a better electron acceptor? Any help is greatly appreciated! "ethanol is a ...
Sunday, November 27, 2016 by Student

Chemistry
A sample of Chlorine occupies 8.50 L at 80.0 C and 740 mm Hg. What volume will Chlorine occupy at STP?
Sunday, November 27, 2016 by riley

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