Wednesday
December 7, 2016

Homework Help: Science: Chemistry

Recent Homework Questions About Chemistry

Chemistry
In a three reactions system the first two reactions are endothermic with DeltaH values of 138kj and 241kj. if the final reaction is exothermic what is the minimum value of DeltaH3 that would make the overall reaction exothermic? explain your reasoning. i beleive the minimum ...
Sunday, October 23, 2016 by Anonymous

Chemistry
Balance the following redox reaction in basic solution. H2(g)+Fe3+(aq) ---> H2O(l)+Fe2+(aq)
Sunday, October 23, 2016 by Anonymous

Chemistry need asap
Situation: The Production of Nitric Acid can be achieved by the following process: Nitrogen monoxide gas(NO) + diatomic oxygen gas+ water (liquid) ===> Nitric Acid (aq) a. Show complete balanced reaction for process What I have: 4NO+ 3O2+ 2H2O > 4HNO3 b. The lab ...
Sunday, October 23, 2016 by John

Chemistry
When 26.16 g of iron is heated in the presence of excess chlorine gas, they will react to form 76.08 g of a compound called ntaining these 2 elements. If the molar mass of this compound is 644 g/mil find the molecular formula.
Sunday, October 23, 2016 by Josh

chemistry
proof that the energy of the first spectra line in Lyman series E =3/4Eo Eo=2.18×10-18
Sunday, October 23, 2016 by mesfin Gebre

Chemistry (atoms)
How many atoms of oxygen, O, are in 0.0595 moles of water?
Sunday, October 23, 2016 by Ray

Chemistry
0.3975 g of an oxide of divalent metal on reduction with hydrogen gives 0.090 g of water. The atomic weight of metal is: a) 63.5 b) 24 c) 55.5 d) 40
Saturday, October 22, 2016 by Avy

Chemistry, que 10
How many atoms are present in one formula unit of calcium hydrogen carbonate Ca(HCO3)2? Could someone explain to me why the answer is 11? Thank you.
Saturday, October 22, 2016 by Cheezel

Chemistry
The principal quantum number (n): 1) specifies the subshell of the orbital. 2) specifies the principal shell of the orbital. 3) specifies the 3-D shape of the orbital. 4) specifies the maximum number of electrons. 5) none of the above
Saturday, October 22, 2016 by Beth

Chemistry
According to the quantum-mechanical model for the hydrogen atom, which of the following transitions would produce light with longer wavelength: 3p to 2s or 4p to 2s? A) The 3p to 2s transition would produce light with longer wavelength. B) The 4p to 2s transition would ...
Saturday, October 22, 2016 by Sue

Chemistry
What happens to an atom when it absorbs energy? 1) The atom stores the energy for later use. 2) The atom re-emits the energy as electromagnetic radiation. 3) The extra energy increases the speed of the electrons in their orbitals. 4) The extra energy increases the oscillation ...
Saturday, October 22, 2016 by Beth

Chemistry
Calculate the wavelength, in nanometers, of the spectral line produced when an electron in a hydrogen atom undergoes the transition from the energy level n = 2 to the level n = 1.
Saturday, October 22, 2016 by Joseoh

Chemistry
Find the frequency if given energy 6.3x10^-19 Do I use the formula E=hf? 6.3x10^-19=6.626x10^-34(f) Then do I divide E and H?
Saturday, October 22, 2016 by Anonymous

Chemistry
calculate the mass ratio of 25% cacl2 solution and water to prepare 500 g of a 5% salt solution
Saturday, October 22, 2016 by Regan

Chemistry
What pressur would the propane gas sample have at 75Ml
Saturday, October 22, 2016 by Teela Lange

Chemistry
A chemist reacted 0.05 mol of sodium with water to form 50cm3 of sodium hydroxide what was the mass of sodium reacted Na+h2p-Noah+h2
Saturday, October 22, 2016 by Maria

Chemistry
A Solution Has A PH Of 3.4.What Is Its Hydrogen Ion Concentration?
Saturday, October 22, 2016 by Ola

Chemistry
The heat of combustion of C2H4 at 27 C at constant prssure is -333.3 Kcal. What will be the heat of combustion at constant volume considering the water to be in liquid state? (R=1.987 cal)
Saturday, October 22, 2016 by Sidharth

Chemistry
In a reversible reaction PCl5 ↔ PCl3 + Cl2, the value of K is 2.5. What will the partial pressure of Cl2 be?
Saturday, October 22, 2016 by Sidharth

chemistry
A Li2+ ion had its electron in an excited state. When the electron relaxed to the ground state (n = 1) a photon of light was emitted with an energy of 1.884×10−17 J. What energy level was the electron in before it transitioned to the ground state?
Friday, October 21, 2016 by malina

Chemistry
The principal quantum number (n): A) specifies the subshell of the orbital. B) specifies the principal shell of the orbital. C) specifies the 3-D shape of the orbital. D) specifies the maximum number of electrons. E) none of the above
Friday, October 21, 2016 by Katelyn

Chemistry 2
The mechanism for the reaction of nitrogen dioxide with carbon monoxide to form nitric oxide and carbon dioxide is thought to be the following. NO2 + NO2 NO3 + NO Slow NO3 + CO NO2 + CO2 Fast What would be the overall balanced equation to this reaction?
Friday, October 21, 2016 by Alanna

Chemistry
The specific heat of a metal was found to be 0.38 J/g*°C. When 0.5007 g of this metal was heated in a stream of chlorine gas, it produced 1.0586 g of a metal chloride, MClx. a. Determine the formula of the metal chloride and the accurate atomic weight of the metal. b. What...
Friday, October 21, 2016 by Anonymous

Chemistry
The compound copper(II) nitrate is a strong electrolyte. Write the reaction when solid copper(II) nitrate is put into water:
Friday, October 21, 2016 by Liz

chemistry
A 45-kg person drinks 390. g of milk, which has a "caloric" value of approximately 3.0 kJ/g. If only 17% of the energy in milk is converted to mechanical work, how high (in meters) can the person climb based on this energy intake? [Hint: The work done in ascending is...
Friday, October 21, 2016 by Dani

chemistry
A 77.40 kg piece of copper metal is heated from 19.6°C to 337.3°C. Calculate the heat absorbed (in kJ) by the metal.
Friday, October 21, 2016 by Dani

chemistry
A sheet of gold weighing 11.4 g and at a temperature of 15.6°C is placed flat on a sheet of iron weighing 24.2 g and at a temperature of 54.9°C. What is the final temperature of the combined metals? Assume that no heat is lost to the surroundings. - (11.4)(0.129)(Tf &#...
Friday, October 21, 2016 by Dani

chemistry
A 0.1219-g sample of solid magnesium is burned in a bomb calorimeter that has a heat capacity of 1769 J/°C. The calorimeter contains exactly 271 g of water, and the temperature increases by 1.126°C. Calculate the heat given off by the burning Mg, in kJ/g and in kJ/mol.
Friday, October 21, 2016 by Dani

CHEMISTRY
write the orbital notation for the following set of quantum numbers n=1, l=0, m=0
Friday, October 21, 2016 by DAVID CHIRISWA

CHEMISTRY FOR ENGINEERS
What is the frequency and wave number associated with light of wavelength equal to 6000 angstrum
Friday, October 21, 2016 by DAVID CHIRISWA

Chemistry
Prepare 0.03 mole fraction solution of NaOH in water Total volume of solution is 100ml
Friday, October 21, 2016 by Faisal

Chemistry
You add 7.326g of solid CaCl2 to 45.5 mL of water in a coffee cup calorimeter and measure as the temp. Increase from 22.6 C to 41.5 C. Specific heat water is 4.184 J/ g.C and the density of water is 0.9977 g/mL. Find the mass of water. PLEASE HELP ME!!!
Thursday, October 20, 2016 by Dania

Analytical chemistry
Calculate to four decimal places the mass of purely dry MgCO3(Magnesium Carbonate) required to make 1L of a 1000 ppm Mg stock solution.
Thursday, October 20, 2016 by cindy

chemistry
How we make 0.02ppm solution in 25ml?
Thursday, October 20, 2016 by Usama munir

Chemistry
i need help making an acrostic poem using the word nonmetal
Thursday, October 20, 2016 by Josh

chemistry need help
Balance the following equation in an acidic and basic medium * Cr^(+3)+BrO^(-)--->CrO4^(2-)+Br^(-)
Thursday, October 20, 2016 by booob

CHEMISTRY
A lamp of marble chips was dropped in excess 0.1mol/dm hydrochloric acid and observed for sometime. (a) State what you would see. (b)Describe how the rate of reaction changed with time. (c)Explain why the reaction stopped after sometime. (d)The reaction was rather slow.State ...
Thursday, October 20, 2016 by BELDEN

chemistry
For the following reaction Co(g)+H2o(g)=Co2(g)+H2(g) If the initial concentrations of Co and H2o are 1.00 mol in a 50 L vessel, what is the number of mole of each species at equilibrium, if the equilibrium constant Kc= 0.85 at 1000 C? please can any one explain how to do this ?
Thursday, October 20, 2016 by b.k

Chemistry
I have a 0.6573g mixture of NaHCO3 and Na2CO3. Calculate the mass of NaHCO3 and Na2CO3 in the unknown mixture.Also calculate the mass of NaCl formed in the reaction of the mixture and HCl.
Thursday, October 20, 2016 by Sam

Chemistry
A 75.0g sample of liquid contains 17.5% by mass of H3PO4 (molar mass = 98.0g/mol). If 215.0mL of Ba(OH)2 is needed to completely neutralize the acid, determine the concentration of the Ba(OH)2 solution used
Thursday, October 20, 2016 by Biplob

Chemistry
Determine the mass of urea, CH2N2O, required to make 250mL of a 0.235 M solution
Thursday, October 20, 2016 by Lauren

Analytical chemistry
Calculate to four decimal places the mass of pure dry CaCO3 required to make 1 L of a 1000 ppm Ca stock solution.
Thursday, October 20, 2016 by Angel

Chemistry
Heat from burning a fuel is absorbed by a copper calorimeter. The calorimeter has a mass of 81.34 g and contains 200.0 g of water initially at 21 degrees Celsius. a) How much heat was absorbed by the calorimeter and the water if the final temperature of the water is 36.40 ...
Thursday, October 20, 2016 by lomonoyan

Chemistry
How much heat is required to melt 110g of ice at-45°C?
Wednesday, October 19, 2016 by Anna

Chemistry
What is the maximum mass, in grams, of NH3 that can be produced by the reaction of 1.0 g of N2 and 1.0 g of H2 using the reaction below? N2+H2→NH3 (not balanced) A) 0.60 g B) 5.7 g C) 1.2 g D) 2.9 g
Wednesday, October 19, 2016 by Katelyn

Chemistry
The number of moles of cl2 produce will be ??????? If one mole of pcl5 is heated at 250 in a vessel having a capacity of 10dm³.
Wednesday, October 19, 2016 by Nabiha

Chemistry
Magnesium oxide can be made by heating magnesium metal in the presence of oxygen. The balanced equation for the reaction is: 2Mg(s)+O2(g)→2MgO(s) When 10.1 g of Mg are allowed to react with 10.5 g of O2, 14.5 g of MgO are collected. a) Determine the limiting reactant for...
Wednesday, October 19, 2016 by Beth

Chemistry
What is the maximum mass, in grams, of NH3 that can be produced by the reaction of 1.0 g of N2 and 1.0 g of H2 using the reaction below? N2+H2→NH3 (not balanced) What is the maximum mass, in grams, of that can be produced by the reaction of 1.0 g of and 1.0 g of using ...
Wednesday, October 19, 2016 by Katelyn

chemistry
If 20 grams of zinc reacts with hydrochloric acid, how much zinc chloride is produced?
Wednesday, October 19, 2016 by sue

Chemistry
Assuming 100% dissociation, calculate the freezing point and boiling point of 2.45 m Na2SO4(aq). Constants may be found here sites. google. com/site/chempendix/colligative.
Wednesday, October 19, 2016 by Mia

chemistry
A 2.41 g lead weight, initially at 10.7 ∘C, is submerged in 8.08 g of water at 51.9 ∘C in an insulated container. Question: What is the final temperature of both the weight and the water at thermal equilibrium? Express the temperature in Celsius to three ...
Wednesday, October 19, 2016 by myah

chemistry
A volume of 115 mL of H2O is initially at room temperature (22.00 ∘C). A chilled steel rod at 2.00 ∘C is placed in the water. If the final temperature of the system is 21.40 ∘C , what is the mass of the steel bar? Use the following values: specific heat of ...
Wednesday, October 19, 2016 by myah

chemistry
increasing order of boiling points of NO2, KCl and N2
Wednesday, October 19, 2016 by Anonymous

Chemistry
A sample of gas occupies 100ml at 25 degree celsius. What volume would the gas occupy at 32 degree celsius if the pressure remains constant
Wednesday, October 19, 2016 by Nur

chemistry
what is the reaction between potassium chloride and bromine?
Wednesday, October 19, 2016 by wes

Chemistry
In the laboratory you will be provided with a 1.0 x 10-5 M primary stock solution of fluorescein (MW=332.31g/mol). The calibration curve should include a blank, 0.025, 0.05, 0.075, 0.10, 0.15, and 0.25 micromolar fluorescein solutions. Since you will be using 25 mL volumetric ...
Wednesday, October 19, 2016 by Guy

chemistry
Calculate the number of CO2 molecules in 7.30×10−2 mole of CO2. Express your answer using three significant figures.
Tuesday, October 18, 2016 by rolando

chemistry
Calculate the number of Li atoms in 3.0 moles of Li. Express your answer using two significant figures.
Tuesday, October 18, 2016 by rolando

chemistry
0.350 L of 0.470 M H2SO4 is mixed with 0.300 L of 0.250 M KOH. What concentration of sulfuric acid remains after neutralization?
Tuesday, October 18, 2016 by james

Chemistry
You are handed a well insulated container holding about 100ml of water at a temp between 75 deg C and 100 deg C. you are given a thermometer with a maxmimum temp of 50 deg C. create an experiment to determine the temp of the water. i am really confused on how to start this ...
Tuesday, October 18, 2016 by Anonymous

Chemistry
In the laboratory you will be provided with a 1.0 x 10-5 M primary stock solution of fluorescein (MW=332.31g/mol). The calibration curve should include a blank, 0.025, 0.05, 0.075, 0.10, 0.15, and 0.25 micromolar fluorescein solutions. Since you will be using 25 mL volumetric ...
Tuesday, October 18, 2016 by Bruce

Chemistry
When 13.0 grams of acetylene, C2H2, is reacted, what mass of water, H2O, is produced?
Tuesday, October 18, 2016 by Joe

chemistry
what is the skeleton chemical equation of this? And Balanced equation. Copper (ii) chloride + Lithium --> Lithium Chloride + Copper
Tuesday, October 18, 2016 by SAM

chemistry
what is the skeleton chemical equation of this? And Balanced equation. Copper (ii) chloride + Lithium --> Lithium Chloride + Copper
Tuesday, October 18, 2016 by SAM

Organic Chemistry
Explain why the formation of one geometric isomer is favored over the other?
Tuesday, October 18, 2016 by Lyndsay

Chemistry
Solid AgNo3 is added slowly to solution of 0.001M Cl,Br,and I a) at what concentration of Ag will AgI precipitating? at what concentration of Ag will AgCl precipitating? at what concentration of Ag will AgBr precipitating? b) calculate the percent % of I ppt before reaching of...
Tuesday, October 18, 2016 by Ali

Chemistry
1) How does the atomic radius change from left to right across a period in the periodic table? A) It tends to decrease*** B)It tends to increase C) It first increases, then decreases D) It first decreases, then increases 2) What is the charge of a cation? A) A positive charge...
Tuesday, October 18, 2016 by Mary

chemistry
Gold has a latent heat fusion of 64.5 J/g. How much energy is required to melt 20.0 g of gold?
Tuesday, October 18, 2016 by Nick

chemistry
Ethyl alcohol has a heat of vaporization of 850. J/g. What mass of ethyl alcohol can be boiled using 15000 J of energy?
Tuesday, October 18, 2016 by Nick

Chemistry
Determine the volume of a 67.5g piece of aluminum with density of 2.70 g/mL? -I know V=M/p and this is what I came up with but I'm not sure i'm correct.. p = 2.7 g/cm3 M = 67.5 g V = 25 cm3 3√ V = 2.9240177382129 cm
Tuesday, October 18, 2016 by Rae

chemistry
A student melts 50.0 grams of ice using 16650 J of energy. What is the heat of fusion of ice?
Tuesday, October 18, 2016 by Nick

Chemistry
Determine the mass of 18.7mL of rubbing alcohol with a density of 0.79 g/mL? - I got 14.77. I'm not sure I'm right. If someone could clarify I'd appreciate it! Thanks!
Tuesday, October 18, 2016 by Rae

Chemistry
A 1.75 gram perfect cube of wood has a side measure of 2.45 cm, what is the density of the wood?
Tuesday, October 18, 2016 by Rae

Chemistry
I Just don't know what to do, I think I understand, but im not sure because all of the compounds are liquid. I would know how to do it if they were aqueous, and just the water is liquid, but they are all liquid. Determine the acid dissociation constant for a 0.10 M acetic ...
Tuesday, October 18, 2016 by Bailey

Chemistry
Solid AgNo3 is added slowly to solution of 0.001M Cl,Br,and I a) at what concentration of Ag will AgI precipitating? at what concentration of Ag will AgCl precipitating? at what concentration of Ag will AgBr precipitating? b) calculate the percent % of I ppt before reaching of...
Tuesday, October 18, 2016 by Ali

Chemistry
What volume of 17 M sulfuric acid must be used to prepare 0.15 L of 1.78 M H2SO4?
Tuesday, October 18, 2016 by Ken

Chemistry
How many moles of magnesium chloride are in 5.43 x 10^24 formula units of magnesium chloride?
Tuesday, October 18, 2016 by Bree

Chemistry
A student measures the molarity of a solution of sodium hydroxide as 0.247M. He leaves the solution in a beaker overnight and then titrates the solution again. This time he is surprised to get a result of 0.225M. Why should he have expected something of this nature?
Tuesday, October 18, 2016 by Garrinique

Chemistry
Write the balanced equations for the reactions: a) Reduction of Ag+ Ions with metal Fe. b) Oxidation of metal Mg with Cu2+ ion.
Tuesday, October 18, 2016 by Christine

CHEMISTRY HELP PLEASEEEE
Sulfuric acid is a diprotic acid, strong in the first ionization step and weak in the second (Ka2=1.1X10^-2). Using appropriate calculations, determine whether it is feasible to titrate 10.00mL of 0.1 M H2SO4 to two distinct equivalence points with 0.1 M NaOH.
Tuesday, October 18, 2016 by Emma

Chemistry
Gives isomeric compound of C3 H8 O woth IULAC names
Tuesday, October 18, 2016 by Khan Hanzala

Chemistry
if the density of 2-butanol is 0.80g ml-1, what volume of 2-butanol would be produced from 1kg of butene
Tuesday, October 18, 2016 by Paris

Chemistry
Since the unkown acid is monoprotic, this also equals the number of moles of acid to use. A typical molar mass for an unknown acid in this experiment is 380 g/mol. Using this molar mass, calculate the mass (in grams) of unknown acid you should use per titration. 1.Suppose that...
Monday, October 17, 2016 by Raeann

Chemistry
1. Suppose that 10.2 mL of 0.0512 M NaOH were required to titrate a sample of unkown acid. How many moles of NaOH were used?
Monday, October 17, 2016 by Raeann

Chemistry
Why was etching needed to bring out the grain boundaries? My answer: Is it for the light to bounce back?
Monday, October 17, 2016 by Chemistry

Chemistry
What mass of calcium citrate, Ca3(C6 H5 O7)2, would a tablet manufacturer need to use to provide the same amount of Ca that you found in your tablet? (show calculations) The mass of Calcium for the experiment was .7374g We assumed that any solid that formed when Na2CO3 was ...
Monday, October 17, 2016 by Chris

Chemistry Plz Help!
How to calculate dimensional analysis using the density and molarity to calculate the percent (w/w)???
Monday, October 17, 2016 by Barbie

Chemistry
0.5g of MG ribbon is reacted with 100ml of 1M HCL. The initial temperature of HCL is 20.4 degrees celsius. After the reaction the highest recorded temperature is 40.7 degrees celsius. Calculate the molar enthalpy of MG. I tried to find mol from HCl and then use nH=mcdeltat. ...
Monday, October 17, 2016 by Jacob

Chemistry
The molar enthalpy of combustion of demand is -6.78KJ/mol.What mass of decane would have to be burned in order to raise the temperature of 500ml of water from 20 degrees Celsius to 55 degrees celsius. I tried using ndeltaH=mcdeltat. But it didn't work. Please help
Monday, October 17, 2016 by Kelvin

Chemistry
1) How does the atomic radius change from left to right across a period in the periodic table? A) It tends to decrease*** B)It tends to increase C) It first increases, then decreases D) It first decreases, then increases 2) What is the charge of a cation? A) A positive charge...
Monday, October 17, 2016 by Mary

Chemistry
Calculations involving a limiting reactant Now consider a situation in which 20.0 g of P4 is added to 54.0 g of Cl2, and a chemical reaction occurs. To identify the limiting reactant, you will need to perform two separate calculations: 1) Calculate the number of moles of PCl5...
Monday, October 17, 2016 by Beth

Organic Chemistry
Butanamide (Amide) vs Aminobutane (Amine) Which compound do you think has the higher melting point? Explain your reasoning.
Monday, October 17, 2016 by matt

Science (Chemistry) Ratio of mole
You measured out 0.101g of Mg. You heat the sample and measure out 0.234 of the magnesium oxide compound. Given your data, what us the empirical formula for the Mg(x)O(y)? x and y are ratio x:y If I'm doing this correctly, I divided 0.101g of Mg/24.31g of Mg = .00415 mol ...
Monday, October 17, 2016 by Ray

chemistry
Calculate the mass of pure NaCl that will yield enough HCl gas to neutralize 25cm3 of 0•5 of KCO3 solution
Monday, October 17, 2016 by Ozioma

chemistry
5. One hundred milligram of caffeine is dissolved in 50 mL of water. a. How many mg of caffeine will remain in the water if you extract with 20 mL of methylene chloride? Show your calculations (KD = 4).b. How many mg of caffeine will remain in the water if you extract two ...
Monday, October 17, 2016 by reem

chemistry
The 17.35 g of NaCl sample was dissolv ed in an unknown amount of water. All we know is that prepared solution has 22.5% of NaCl . The mass of water is _____ g.
Monday, October 17, 2016 by shawna

Chemistry
A sample of cobalt, A, with a mass of 5g is initially at 25 degrees Celsius. When this sample gains 6.70J of heat, the temperature rises to 27.9 degrees Celsius. Another sample of cobalt B with a mass of 7 g is initially at 25 degrees Celsius. If sample B gains 5 J of heat, ...
Monday, October 17, 2016 by Matthew

Chemistry
A solution of potassium permanganate (KMnO4) was standardised by titrating with 0.1908 g of Na2C2O4 dissolved in 50 cm3 of acidified water. The endpoint was reached after 24.50 cm3 of solution had been added. Calculate the molar concentration of KMnO4 in the solution.
Monday, October 17, 2016 by Anonymous

Chemistry
A solution of potassium permanganate (KMnO4) was standardised by titrating with 0.1908 g of Na2C2O4 dissolved in 50 cm3 of acidified water. The endpoint was reached after 24.50 cm3 of solution had been added. Calculate the molar concentration of KMnO4 in the solution.
Monday, October 17, 2016 by Anonymous

Chemistry
Calculate the molarity of Fe(NO3)3 in Solution A. Solution A: Mass of Fe(NO3)3 solid: 1.21g & Vol of Solution: 100mL In a previous ? Using the mass I weighed 404.0g/mol to calculate moles of Fe(NO3)3 in solid hydrate----I got 0.00300 mol Fe(NO3)3)
Monday, October 17, 2016 by Rosie

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Homework Help: Science