Saturday
July 23, 2016

Homework Help: Science: Chemistry

Recent Homework Questions About Chemistry

Math
In a class of 100 students, 40 offer Biology and 10 offer Chemistry and Biology .10 offer Physics and Chemistry , and 30 offer Physic and Biology . Each student offer at least one of the three subjects. The number of students who offer Biology is equal to those who offer ...
Thursday, June 9, 2016 by Delson

chemistry
what fraction of voids are occupied by sp3 carbon in diamond
Thursday, June 9, 2016 by Anushka

Chemistry
A solution of acetic acid, 1.0 mol L–1 CH3COOH, contains sodium acetate, NaCH3COO. The percent ionization of the above solution is 0.25%. The Ka for acetic acid is 1.8 x 10–5. Which of the following is the concentration of NaCH3COO in acetic acid? So i use ...
Thursday, June 9, 2016 by luis

chemistry
The Kb of ammonia is 1.8 x 10–5. What is the percent ionization of a solution of ammonia, 0.50 mol L–1 NH3, that contains 0.020 mol L–1 of ammonium nitrate, NH4NO3? when i use the ICE table i dont end up with an unknown so im not sure what to do. ...
Thursday, June 9, 2016 by James

chemistry
At equilibrium, a solution of formic acid at 25°C has a pH of 2.18. The pKa of formic acid, HCOOH, is 3.74. Which of the following is the initial concentration of the solution? Not sure what to do my thoughts: use henderson hasselback equation pH = pKa + log [conj ...
Wednesday, June 8, 2016 by James

chemistry
. Which of the following is not a way an atom can achieve stability?
Wednesday, June 8, 2016 by donna

Math
in a class of 60 students 30 like maths 25 like physics 30 like chemistry. if 10 like both physics and maths 5 like maths and chem and 5 like phy & chem and 3 like all the subjects. find student like none of subject if 100 students were surveyed
Wednesday, June 8, 2016 by Anonymous

Math
in a class of 60 students 30 like maths 25 like physics 30 like chemistry. if 10 like both physics and maths 5 like maths and chem and 5 like phy & chem and 3 like all the subjects. find student like none of subject of if 100 students were surveyed
Wednesday, June 8, 2016 by Dp

Chemistry
When the equation Fe + O2→Fe2O3 is balanced, the coefficient for O2 is: A. 4 B. 3 C. 1 D. 2 D?
Wednesday, June 8, 2016 by quick help please

Chemistry
A catalyst is: A. a solid product of a reaction. B. one of the reactants in a single-replacement reaction. C. not used up in a reaction. D. the product of a combustion reaction. C?
Wednesday, June 8, 2016 by quick help please

Chemistry
In order for the reaction 2Al(s) + 6HCl(aq)→2AlCl3(aq) + 3H2(g) to occur, which of the following must be true? A. Al must be above Cl on the activity series. B. Al must be above H on the activity series. C. Heat must be supplied for the reaction. D. AlCl3 must be a ...
Wednesday, June 8, 2016 by quick help please

Chemistry
The equation Ba(s) + HCl(aq)→BaCl2(aq) + H2(g) is an example of which type of reaction? A. double-replacement B. combustion C. single-replacement D. decomposition C?
Wednesday, June 8, 2016 by quick help please

Chemistry
At 25°C, the methylaminium ion, CH3NH3+, has a Ka of 2.0 x 10–11. Which of the following is the pH of a 0.15 mol L–1 solution of methylamine? i tried out two methods because im not getting the right answer: H20 + Ch3Nh2 -> CH3NH3+ + OH- I made a...
Wednesday, June 8, 2016 by Please help I tried for so long!

chemistry
The pKb of ammonia, NH3, is 4.74 at 25°C.  Which of the following is the Ka of the ammonium ion, NH4+? not sure what to do, this is what i have i guess: kb = -log 4.74 ----- pKa + pKb = 14 pKa = 9.26 ka = -log 4.26 = -0.676 ----- Ka = [NH4+][OH-]/ [NH3]
Wednesday, June 8, 2016 by chem101

chemistry
If at moment t=0 ,separation between cars is 100m.The separation between them at the moment t=2s can be?
Wednesday, June 8, 2016 by abhay

Analytical Chemistry
How do we do the calculations when carrying out an experiment on titrating 99% of 0.1molar of NaOH and 99% of 0.1molar of Sulphuric acid in a 1 litre?
Wednesday, June 8, 2016 by Anonymous

chemistry
What is the difference between molecular compounds, covalent compounds and covalent bounds
Wednesday, June 8, 2016 by AMELIA

chemistry
The equilibrium constant for the reaction Cu3(PO4)2(s)    3 Cu2+(aq)  +  2 PO43–(aq) is K = 1.40 x 1​0–37.  Suppose that a beaker is filled to 1 L with a solution containing [Cu2+] = [PO43–] = 10.0 nM...
Tuesday, June 7, 2016 by jess

chemistry
Consider the information given below ΔH⁰/ kJmol-1 Enthalpy of lattice formation for CaF2 -2611 Enthalpy of hydration for Ca2+ ions -1650 Enthalpy of hydration for F- ions -506 Using the information given above, calculate the enthalpy of solution for CaF2
Tuesday, June 7, 2016 by chansa

chemistry
Acids and bases • What is an acid? • A 500cm3 solution containing 1.9g of a weak acid HA has a pH of 3.50. Calculate the molar mass of the acid, given that it has a Ka of 2.0 × 10-6moldm-3 • Calculate the pH of the following: • 0.002moldm-3 NaOH &#...
Tuesday, June 7, 2016 by chansa

chemistry
a) Define the following terms: • Electronegativity • Bond polarity • Ionization energy b) What is the difference between ionic bonds, covalent bonds and polar covalent bonds? Give two examples of each c) Draw Lewis structures for each of the following: • ...
Tuesday, June 7, 2016 by chansa

Chemistry
Which symbol correctly represents an element (D) whose atoms contain 15 protons and 20 neutrons? A. 20/15 D B. 15/20 D C. 35/15 D D. 15/35 D C?
Tuesday, June 7, 2016 by quick help needed

Chemistry
Which of the following statements is not consistent with the results obtained in Rutherford’s gold foil experiment? A. The nucleus of an atom is positively charged. B. The nucleus of an atom contains almost all the mass of the atom. C. Atoms are composed mainly of empty ...
Tuesday, June 7, 2016 by quick help needed

Chemistry
How would you prepare pure dry crystals of potassium trioxocarbonate (v)
Monday, June 6, 2016 by Jenifer

Chemistry
How many moles are in 7.5x10^24 molecules of carbon dioxide? Grams?
Monday, June 6, 2016 by Jake

chemistry
when measuring latent heat, why should your final temperture be the minimum temperature reached by the calorimeter?
Monday, June 6, 2016 by asasasas

chemistry
'Aluminium displaces hydrogen from dilute HCl whereas silver does not. The E.M.F. of a cell prepared by combining Al /Al 3 andAg/Ag is 2.46 V. The reduction potential of silver electrode is 0.80 V. The reduction potential of aluminium electrode is :
Monday, June 6, 2016 by Anushka

Chemistry
An aqueous solution that 2.00 M in AgNO3 is slowly added from a buret to an aqueous solution that is 1.00×10−2 M in Cl− and 0.260 M in I−. When the second ion begins to precipitate, what is the remaining concentration of the first ion? I know that the ...
Sunday, June 5, 2016 by Sydney

Chemistry
How many grams of cesium chloride (CsCl) will be needed to make 750. mL of a 0.100 M CsCl aqueous solution? The formula mass of CsCl is 168.36 g/mol
Sunday, June 5, 2016 by Eddie

chemistry
Propane, C3H8, reacts with oxygen according to the following balance equation. If 44 grams of propane react completely with sufficient oxygen, how many grams of water are produced?
Sunday, June 5, 2016 by salende

chemistry
a solution of nickel sulphate in which nickel rod is dipped is diluted 10 times. the reduction potential of Ni at 298 K is?
Sunday, June 5, 2016 by Anushka

chemistry
If 0.5 moles of bacl2 is mixed with 0.2 moles na3po4 then maximum no.of moles of nacl formed is?
Sunday, June 5, 2016 by abhay

Chemistry
A student estimated a mass to be 250 g but, upon carefully measuring it, found the value to be 240 g. What is the percent error of the estimated mass if the measured value is the accepted one? A. 4.2% B. 4.0% C. -4.2% D. -4.0% D?
Sunday, June 5, 2016 by quick help needed

chemistry
How many significant figures are in the measurement 603.040 g? A. 3 B. 4 C. 5 D. 6 C?
Sunday, June 5, 2016 by quick help needed

chemistry
A current of 96.5 A is passed for 18 min between nickel electrodes in 500 mL solution of 2M Ni(NO3)2. The molarity of solution after electrolysis would be
Sunday, June 5, 2016 by Anushka

chemistry
Which of the following is not a part of the scientific method? A. hypothesizing B. experimenting C. observing D. proving D?
Sunday, June 5, 2016 by quick help needed

Analytical Chemistry
Could someone show me step by step how to solve this type of problem? I have to do several of them, and would love to understand what is actually happening! Thank you so much in advance, I appreciate your help and time! Calculate the weight percent of ascorbic acid in a tablet...
Sunday, June 5, 2016 by DeeDee

Chemistry
How many ammonia liters of ammonia gas are produced when 85 grams of liquid nitrogen completely react? N2 + 3H2 = 2NH3
Saturday, June 4, 2016 by Macario

Chemistry
For the equilibrium system below, which of the following would decrease the concentration of 𝑃𝐶𝑙3(𝑔)?​ 𝑃𝐶𝑙3(𝑔) + 𝐶𝑙2(𝑔) ↔ 𝑃𝐶𝑙5(𝑔) + 45𝑘&#...
Saturday, June 4, 2016 by Help:(

Chemistry
7. For the equilibrium system below, which of the following would increase the concentration of 𝐻2𝑂(𝑔)? 𝐶(𝑠) + 𝐻2𝑂(𝑔) + 131𝑘𝐽 ↔ 𝐶𝑂(𝑔) + 𝐻2(𝑔) a. ...
Saturday, June 4, 2016 by Urgent

Chemistry
One of the issues caused by acid rain is the lowering of pH of small lakes, which leads to the death of numerous aquatic fish and plant species. Calcium oxide, commonly known as lime, is frequently used to temporarily remediate lakes that have been acidified by acid rain. ...
Saturday, June 4, 2016 by John Lee

chemistry
aluminum sulfide reacts with water to form aluminum hydroxide and hydrogen sulfide a. balance the chem eqn for this rxn Al2S3+6H2O = 2Al(OH)3+3H2S b.how many g of water are needed in the rxn to produce al(oh)3? what is the formula i use here?? c. how many g of al(oh)3 are ...
Saturday, June 4, 2016 by shi

Chemistry Homework
Backpackers often use canisters of white gas to fuel a cooking stove’s burner. If one canister contains 2.45dL of white gas, and the density of the gas is 0.720g/cm3, what is the mass of the fuel in kilograms? So Volume=2.45dL(10L/1dL)=24.5L(1000/1)=245​00cm^3 D=m/v...
Friday, June 3, 2016 by Leo

Chemistry
What is the mobile phase in this experiment? A) 10% 6M NaOH and 90% acetone B) 10% 6M HCl and 90% acetone C) 10% 5M KCl and 90% methanol D) 10% 5M KCl and 90% acetone Gel electrophoresis is an example of which type of chromatography? A) Column chromatography B) Gas ...
Friday, June 3, 2016 by Jon Riley

Chemistry
How many ammonia liters of ammonia gas are produced when 85 grams of liquid nitrogen completely react? N2 + 3H2 = 2NH3
Friday, June 3, 2016 by Macario

chemistry
Suppose a substance has been prepared that is composed of carbon, hydrogen, and nitrogen. When 0.1156 gram of this compound is reacted with oxygen, 0.1638 gram of carbon dioxide (CO2) and 0.1676 gram of water (H2O) are collected. Assuming that all the carbon in the compound ...
Friday, June 3, 2016 by Chansa

chemistry
show by calculation of z the behavior of (.25 mole) gas sample at the following conditions (ideal or real)at temperature 100c 1-p=0.25 v=12
Friday, June 3, 2016 by kamal

Chemistry
The combustion reaction of propane is described by the reaction. C3H8 + 5O2 → 4H2O + 3CO2. How many moles of O2 are required to generate 3 moles of CO2? 2.5 moles 3 moles 4 moles 5 moles
Friday, June 3, 2016 by Wesley

Chemistry
How many ammonia liters of ammonia gas are produced when 85 grams of liquid nitrogen completely react? N2 + 3H2 = 2NH3
Friday, June 3, 2016 by Macario

chemistry
a compound or solute with molecular mass 36?
Friday, June 3, 2016 by Anonymous

chemistry
a compound or solute will molecular mass 36?
Friday, June 3, 2016 by kartik

Chemistry
How many electrons are present in 0.002 moles of O--?
Friday, June 3, 2016 by Abhinav

Chemistry/- Dr.Bob222
A voltaic cell consists of a Zn/Zn2+ half-cell and a Ni/Ni2+ half-cell at 25 C. The initial concentrations of Ni2+ and Zn2+ are 1.50 M and 0.10 M, respectively. a. What is the initial cell potential? My answer: 0.56 B b. What is the cell potential when the concentration of Ni2...
Thursday, June 2, 2016 by Nevaeh

chemistry
I was given the following problem: what is the normality of a solution containing 6 grams of H2SO4 in a 200ml solution? my teacher obtained a normality of 39normals while I took into account that I had two hydrogen free and obtained a result of 0.6 N, who's right?
Thursday, June 2, 2016 by Paul

Chemistry
a 0.20 mol/l solution of weak base hpo4 has a ph of 9. find the Kb
Thursday, June 2, 2016 by Dawn

Chemistry
A buffer was prepared by mixing 0.1 M ch3cooh with 0.1M ch3cooNa in the ratio 8:2. Calculate ph after the addition of 2mL of 0.1 M HCl? When you do the 8:2 ratio and add 2 mL of 0.1 M HCl, the buffer is gone and you are left with 1*10^-3 moles of ch3cooh. How would you ...
Thursday, June 2, 2016 by Bobby

chemistry
Calculate the loss in mass if 20.2g of KNO3 crystals was completely decomposed(K=39,N=14,O=16
Thursday, June 2, 2016 by Deborah

Chemistry
Check my answers 63. What type of bond links the monomers together in a polymer? Poly bond Covalent bond Ionic bond Hydrogen bond*** 64.What is the change in atomic mass when an atom emits a beta particle? decreases by 1*** increases by 1 decreases by 2 remains the same 65. ...
Thursday, June 2, 2016 by Kayla

Chemistry
The acetate buffer were prepared by mixing 0.1 M ch3cooh with 0.1M ch3cooNa in the ratio 8:2 and 2:8. Calculate the resulting ph after the addition of 2mL of 0.1 M HCl to 10 ml of buffer 8:2 and 4ml of 0.1 M NaOH to 10 ml of buffer 8:2.
Thursday, June 2, 2016 by Bobby

Chemistry
You are given Ka of carbonic acid is 4.3 x10^-7. This means that Carbonic acid is a good hydrogen-ion acceptor*** good hydrogen-ion donor poor hydrogen-ion acceptor poor hydrogen-ion donor
Thursday, June 2, 2016 by Kayla

Chemistry
Calculate the molality of a solution prepared by dissolving 225.5 g KNO3 in 825mL of water. Show your work
Thursday, June 2, 2016 by Kayla

chemistry
A certain first order reaction has a rate constant of 5.68 x 10–3 s–1 at 139°C and a rate constant of 8.99 x 10–1 s–1 at a temperature of 215°C. Ea = 111 kJ mol– q1) What is the value of the rate constant at 275°C? q2) ...
Thursday, June 2, 2016 by jane

Chemistry
Calculate the pH of a mixture of 20.0 mL of 0.150 M HCl and 10.0 mL of 0.300 M NaOH.​[7.00]
Thursday, June 2, 2016 by Sihle

Chemistry
98.4 * (1/2)^(19/3.8) = 3.075 g CH3COOH*** H2PO4^– LiOH NH3
Wednesday, June 1, 2016 by Kira

Chemistry
What is the one standard atmosphere of pressure in kilospascals 0 kPa 1 kPa*** 101.3 kPa 760 kPa
Wednesday, June 1, 2016 by Nikkie

Chemistry
Use an analogy from everyday life that can define the term half-life
Wednesday, June 1, 2016 by Nikkie

Chemistry
Why does the mass and charge of an alpha particle make it less penetrating than a beta or gamma? Discuss both the mass and the charge
Wednesday, June 1, 2016 by Nikkie

Chemistry
How can an element be artificially transmuted? Give an example that has an element and what it is transmuted into
Wednesday, June 1, 2016 by Nikkie

Chemistry
The radioisotope radon-222 has a half-life of 3.8 days. How much of a 98.4 g sample of radon -222 would be left after approximately 19 days?
Wednesday, June 1, 2016 by Nikkie

chemistry
In a certain experiment, the rate constant, k, was measured as a function of the temperature, T.  Two data points were as follows: (A) 25°C, 1.1 x 10–5 min–1, and (B) 225°C, 2.4 x 10-2 min–1. The student who performed the experiment then ...
Wednesday, June 1, 2016 by jessica

Chemistry
At 425°C, a reaction has a rate constant of 7.7 x 10–4 s–1 and has an activation energy of 275 kJ mol–1. What is the frequency factor? The answer is 2.9 x 1017 s–1 , I need help with working out I used arrhenius equation and rearranged ...
Wednesday, June 1, 2016 by jessica

Science - Chemistry
How many atoms in a diamond.
Wednesday, June 1, 2016 by Ebony

Chemistry - Dr.Bob
Predict the half-reactions occurring at the anode and the cathode for the electrolysis of aqueous Na2SO4.
Wednesday, June 1, 2016 by Nevaeh

Chemistry
When the ratio of neutron-to-proton dictates that a neutron must break down it will form a helium nucleus an alpha particle a proton and an electron*** Two protons
Wednesday, June 1, 2016 by James

Chemistry
Which of the following materials is necessary to stop gamma radiation one foot of concrete single sheet of paper thin pieces of wood three inches of lead***
Wednesday, June 1, 2016 by James

chemistry
what are the products of a concentrated hydrochloric acid if inert electrodes are used
Wednesday, June 1, 2016 by Anonymous

chemistry
What quantity of CaCO3 (limestone) on heating will give 112g of CaO?
Wednesday, June 1, 2016 by sadaf

Chemistry
What's the formula for Li2Co3+Co(NO3)3(aq) ->
Wednesday, June 1, 2016 by Johnny

Chemistry
Identify the compound and classify its functional group in the image H H H H H H H-C-C-C-O-C-C-C-H H H H H H H
Wednesday, June 1, 2016 by Holly

Chemistry
a 0.20 mol/l solution of weak base hpo4 has a ph of 9. find the Kb
Wednesday, June 1, 2016 by Dawn

Chemistry
How do i calculate the pH of 0.0020mol/l HCl
Wednesday, June 1, 2016 by Buck

Chemistry
Why are the molecules of hydrocarbons nonpolar? The intermolecular attractions are strong. The electron pair is shared almost equally in all the bonds. All the bonds are single covalent bonds*** Van der Waals forces overcome polarity
Wednesday, June 1, 2016 by Abby

Chemistry
Balance the following redox equation using the oxidation number change method. Describe each step that is involved Al(s) + PbSO4 - - > Al2(SO4)3 + Pb(s)
Wednesday, June 1, 2016 by Abby

chemistry
what are the products of a concentrated solution of magnesium chloride if the electrodes used are inert
Wednesday, June 1, 2016 by Anonymous

Chemistry
Tell how a voltaic cell works. Be sure to mention the various parts of the voltaic cell and what they have to do with how it works
Wednesday, June 1, 2016 by Evan

Chemistry
What is the standard cell potential of a cell made of theoretical metals Ms/Ma^+2 and Mb/Mb^+2 if the reduction potentials are -0.19V and -0.85 V, respectively? +0.66V -0.66V +1.04 V*** -1.04V
Wednesday, June 1, 2016 by Kristin

Chemistry
What symbol is used to show the standard reduction potential of an oxidation reaction in a half cell? The sub means what follows is a subscript So the 0 is a superscript and the sub is its subscript E^0 sub cell*** E^0 sub red E^0 sub oxid All of the above
Wednesday, June 1, 2016 by Kristin

Chemistry
To charge a lead storage battery you must apply a direct current to it. hold a magnet close to it. force alternating current through it.*** increase the pressure on it.
Wednesday, June 1, 2016 by Kristin

Chemistry
The volume of a gas is increased from 100mL to 250 mL by heating it.If the original temperture of the gas was 15.0°c what will be the final temperture in °c
Tuesday, May 31, 2016 by Mayra

Chemistry
Magnesium chloride hexahydrate has a density of 1.69 g/cm3. What is the volume in liters of 1.5 x10^2 pounds of MgCl2*6H2O? yes D=m/v into V=m/d, Do I need to find the formula mass of Magnesium chloride hexahydrate and change pounds into liters? Divide the found numbers and I ...
Tuesday, May 31, 2016 by Kim

Chemistry
In the zinc-copper cell, Zn(s) | Zn^+2(1M) || Cu^+2(1M) | Cu(s), which electrode is negative? Cu^+2 Cu(s) Zn(s)*** Zn^+2
Tuesday, May 31, 2016 by Samuel

Chemistry
What is the oxidation half reaction for the following equation: Cr2O7^-2 +Fe+2 - - > Cr^+3 + Fe^+3 Cr^+3 - - > Cr2O7^-2 Fe^+2 - - > Fe^+3 Fe^+3 - - > Fe^+2 Cr2O7^-2 - -> Cr^+3***
Tuesday, May 31, 2016 by Samuel

Chemistry
What is the reducing agent in the following reaction? 2K + S - - > K2S K*** S K2S None of these
Tuesday, May 31, 2016 by Samuel

chemistry
Some physical properties of water are shown below: melting point 0.0°C boiling point 100.0°C specific heat solid 2.05 J/g·°C specfic heat liquid 4.184 J/g·°C specific heat gas 2.02 J/g·°C ΔH° fusion 6.02 kJ/mol ΔH° ...
Tuesday, May 31, 2016 by Selena

Chemistry
How many moles of silver will be deposited from a silver (i) trioxonitrate (v) solution by 16.0g of copper (Ag=108,Cu=63.5)
Tuesday, May 31, 2016 by Gift

Chemistry
find the concentration of h3o in a .86mol/l solution of the weak acid H2O2 (kA=2.4x10-12)
Tuesday, May 31, 2016 by Buck

Chemistry
Find the concentrations of all species in a 0.10mol/l solution of NaOH
Tuesday, May 31, 2016 by Buck

Chemistry- Dr.Bob222
Using the Nernst equation, determine the diluted concentration for both cells. Show your work. Sn| Sn2+(diluted)||Cu2+|Cu Zn| Zn2+ ||Sn2+(diluted)|Sn
Monday, May 30, 2016 by Anonymous

Chemistry!!! PLZ PLZ HELP!!
Calculate the equilibrium amounts of each susbtance in the reaction below if an initial amount of 0.1 moles of H2 are brought together with an initial amount of 0.2 moles of I2 and then equilibrium is established at 900K. Kc at this temperature=70. H2 + I2 <-> 2HI
Monday, May 30, 2016 by Sabrina

Chemistry
A 25.0-g sample of sodium hydroxide is dissolved in 400.mL of water. What is the concentration of the solution?
Monday, May 30, 2016 by Mayra

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