Tuesday
September 1, 2015

Homework Help: Science: Chemistry

Recent Homework Questions About Chemistry

Chemistry
A helium balloon contains 0.50 g of helium. Given the molecular weight of helium is 4.0 g/mol, how many moles of helium does it contain?
Friday, July 3, 2015 by Anonymous

Chemistry
Calculate the volume of solution that has a vapour pressure of 31.27 mbar and contains 84.3g of sucrose, at a temperature of 25.0C. The vapour pressure of pure water at 25.0C is 31.7mbar, the density of water is 1.00g/mL, and assume no change in volume occurs upon dissolution.
Friday, July 3, 2015 by B

Chemistry
If I were to explain to someone about how to find a charge of an element, would anyone agree with this: The charge of an element is determined by the gain or lose of electrons. Depending on how close they are to the left/right side of the periodic table concludes their charge...
Thursday, July 2, 2015 by Joey

Chemistry
1) Which group of elements is the least reactive? Explain why. 2) What properties distinguish metalloids from other elements? 3)Explain how to predict the charge usually observed for a monatomic ion.
Thursday, July 2, 2015 by Anonymous

Chemistry
How many GRAMS of boron are present in 3.54 moles of boron trifluoride
Thursday, July 2, 2015 by Anonymous

Algebra
70 students are studying mathematics,physics & chemistry.40 students study mathematics,35 study physics and 30 study chemistry.15 students are studying all the three subjects.How many students are studying exactly two of the subjects
Thursday, July 2, 2015 by Anika

chemistry
calculate the molal solution depression constant of a solvent which has freezing point 16.6° and latent heat of fusion 180.75J/g 3.3 3.86 2.9 38.6
Thursday, July 2, 2015 by please............

Chemistry
Predict the answer to each question according to trends in the periodic table. Justify each answer based on the locations of the elements on the periodic table and/or the shell model. a. Which has a greater atomic radius, Al or Cl? b. Which has a greater ionic radius, Na or S...
Wednesday, July 1, 2015 by Madison

Chemistry
How many grams of NaOH are needed to make 450mL of a 2.5%(m/v) NaOH solution?
Wednesday, July 1, 2015 by Telimm

Chemistry
What is the net ionic equation, including phases, for the reaction of AgNO3(aq) with K2SO3(aq)
Wednesday, July 1, 2015 by Patty

Chemistry
How many grams of NaCl are present in 1.5L of a 0.25M NaCl solution?
Wednesday, July 1, 2015 by Telimm

Chemistry
Analyze each table of ionization energy data (in kJ/mol) to identify each element. a. A Period 3 element (1 point) IE1: 496, IE2: 4562, IE3: 6910, IE4: 9453, IE5: 13354, IE6: 16613, IE7:20117 b. A Period 5 element (1 point) IE1: 403, IE2:2633, IE3: 3860, IE4:5080, IE5: 6850, ...
Wednesday, July 1, 2015 by Madison

Chemistry
I know Chadwick found/discovered the neutron, but my textbook does not state what experiment he did to find it. Can someone briefly state what he did to find the atom?
Wednesday, July 1, 2015 by Anonymous

Chemistry/reading
Although Rutherford's model was highly successful, scientists realized that it was incomplete. For example, hydrogen atoms contain one proton, and helium atoms contain 2, yet a hydrogen atom has only 1/4 the mass of a helium atom. I'm not comprehending what my textbook...
Wednesday, July 1, 2015 by Anonymous

Chemistry
Describe 3 experiments, run prior to 1930, and the types of energies/particles used to probe the structure of the atom. What did each experiment investigate? Include the names of the scientists associated with each experiment in your answer.
Wednesday, July 1, 2015 by Anonymous

Chemistry
Determine what this molecule should really be named. 2,2-ethylpent-3-ene I get the answer 2,2-diethylpent-3-ene. Why would the answer be: 4-ethyl-4-methylhex-2-ene
Wednesday, July 1, 2015 by Sara

chemistry
A sample of ammonium phosphate(NH4)3PO4 contains 3.18 moles of hydrogen atoms. The number of moles of oxygen atoms in the sample is (1)0.265 (2)0.795 (3)1.06 (4)4.00
Wednesday, July 1, 2015 by Anonymous

chemistry
A sample of ammonium phosphate (NH4)3PO4 contains 3.18 moles of hydrogen atoms then the on. of moles of oxygen atoms in the sample is
Wednesday, July 1, 2015 by Priti

chemistry
Nitrogen forms five compounds with oxygen in which1.0g of nitrogen combines with0.572,1.14,1.73,2.28,2.85 of oxygen respectively. verify law of multiple proportions.
Tuesday, June 30, 2015 by gurlabh

Chemistry
Draw a diagram to illustrate your explanation of how the charge of a single electron was determined. I'm suppose to draw a picture to show how they determined electrons were negative, but am unsure of what to draw for it. One of my ideas is to draw a cathode ray tube with ...
Tuesday, June 30, 2015 by Anonymous

Chemistry
How does a cathode ray tube work? What I want to write: Energy is given to the cathode , thus allowing an energy beam to be crated between the positive charge on one end of the tube, and the negative charge on the other end. Can I add anymore? Also, would it be reasonable to ...
Tuesday, June 30, 2015 by Anonymous

St. Basil's school: Chemistry
The pressure of a gas having volume 1800ml. Originally occupying 300ml. at 6 atms. Pressure.
Tuesday, June 30, 2015 by Richa

Chemistry
Calculate the number of moles of CuSO4 contained in 100 ml of 1mole CuSO4 solution. Also find the number of SO4 ~~ ions in it .?
Tuesday, June 30, 2015 by Awadhesh kumar

Chemistry
Calculate the volume occupied by 5.25 g of nitrogen at 26*c [temperature] and 74.2 cm of pressure.?
Tuesday, June 30, 2015 by Awadhesh kumar

Chemistry
A is a solution of hcl containing 7.30gdm^-3 and B is a solution of X2CO3 containing 10.6gdm^-3.calculate the concentration of A in Moldm^-3
Monday, June 29, 2015 by Caleb

Chemistry Subatomic particles
What data led to the need for change in Daltons ideas?
Monday, June 29, 2015 by Anonymous

Chemistry Subatomic particles
What data led to the need for change in Daltons ideas?
Monday, June 29, 2015 by Anonymous

Chemistry Subatomic particles
Fill in the chart (Numbers correspond to each other[I.E 1 in 1st group connects with 1in 2nd]) Subatomic particle found 1.Proton 2.Neutron 3.Electron Scientist 1.Rutherford 2.Chadwick 3.Thomson Experiment 1.Gold Foil Experiment? 2.? 3.Cathode Ray Tube Data Supporting Discovery...
Monday, June 29, 2015 by Joey

Organic Chemistry
Please help! Thank you! Alcohols can act either as weak acids or as weak bases, just as water can. Show the reaction of methyl alcohol, CH3OH, with a strong base such as Na+ -NH2
Monday, June 29, 2015 by Anonymous

Chemistry
How come lead is denser than copper though more copper atoms can fit into a same size cube than lead atoms can?
Monday, June 29, 2015 by Joey

Chemistry
When heated to 350. ∘C at 0.950 atm, ammonium nitrate decomposes to produce nitrogen, water, and oxygen gases: 2NH4NO3(s)→Δ2N2(g)+4H2O(g)+O2​(g) Using the ideal gas law equation, calculate the volume, in liters, of water vapor produced when 21.8 g of ...
Monday, June 29, 2015 by Telimm

Chemistry
Copper and lead had different densities. Sketch a diagram at the particular nature of matter level showing the atoms of a small cross section of copper and lead. Use this diagram to explain why lead is denser than copper. I couldn't find any pictures or see anywhere in my ...
Monday, June 29, 2015 by Anonymous

Chemistry
472 mL of H2 was collected over water when 1.256g Zn reacted with excess HCl. The atmospheric pressure during the experiment was 754 mmHg and the temp was 26C. What is the pressure in atm of the dry hydrogen gas in the mixture. I don't know how to answer this.
Monday, June 29, 2015 by Stan

Chemistry
What volume of 0.5M NaOH must be added to 50mL of .0.1M benzoic acid to make 100.0 mL of 0.05 M benzoate buffer that is pH 4.5?
Monday, June 29, 2015 by Kathys

Chemistry
If the mole fraction of ethanol in aquas solution is 0.05 . Calculate morality of solution ? Explain it's.
Monday, June 29, 2015 by Awadhesh kumar

Chemistry
What volume of 0.5M NaOH must be added to 50mL of .0.1M benzoic acid to make 100.0 mL of 0.05 M benzoate buffer that is pH 4.5?
Monday, June 29, 2015 by Kathy

Chemistry
Consider the reaction: 2Mg + O2 ------> 2MgO The reaction is at equilibrium, the concentration of MgO is found to be 0.5. What is the concentration of Mg and O2? ----------------------------------------​--------------- Keq is not given... using the ICE table, I ended ...
Monday, June 29, 2015 by Annie

Chemistry
Consider the reaction: 2Mg + O2 ------> 2MgO The reaction is at equilibrium, the concentration of MgO is found to be 0.5. What is the concentration of Mg and O2? ----------------------------------------​--------------- Keq is not given... using the ICE table, I ended ...
Monday, June 29, 2015 by Annie

chemistry
10.5 g sample of copper metal at 25.0°C is heated by the addition of 150.0 J of energy. The final temperature of the copper is _____°C. The specific heat capacity of copper is 0.38 J/ goC.
Monday, June 29, 2015 by jennifer

Chemistry
What data led to the development of the Law of Multiple Proportions? Give an example and explain why this law is important in chemistry. Would this be a good answer: John Dalton used the same observations he used for his law of definite proportions to help develop the law of ...
Sunday, June 28, 2015 by Jack

Chemistry
Why aren't the properties of sodium chloride the same as the elements that compose it?
Sunday, June 28, 2015 by Jill

chemistry
In the reaction of sodium metal with chlorine gas to form sodium chloride, how does chlorine form an anion? Write an equation to support your answer. I know that chlorine becomes an anion since it's gaining an electron from sodium, but how do I show that in an equation?
Sunday, June 28, 2015 by Anonymous

chemistry
correct the following examples of gasses to standard temperature. (assume pressure is constant)(STP stands for standard temp and pressure which is 273K and 101kPa, you do no have to think about the pressure for these four but on the last three you will have to so T2 is 273K ...
Sunday, June 28, 2015 by Anonymous

chemistry
A compound is found to contain 15.12 % phosphorus, 6.841 % nitrogen, and 78.03 % bromine by weight. what is the emperical formula
Sunday, June 28, 2015 by Jeremy

general chemistry
P in PCl5 has a trigonal planar right? Cl2=P=Cl2 | Cl1 is it right? help me how to determine the angle
Sunday, June 28, 2015 by faye

chemistry
If 5.40 kcal of heat is added to 1.00 kg of water at 100 degrees celsius, how much steam at 100 degrees celsius is produced?
Sunday, June 28, 2015 by olaf

organic chemistry
whats the difference between inorganic chem and organic chem? im really confuse because mrs. white told us inoraganic is about ionic bonds while organic is about covalent bond. what is the difference between the twooo? please help me
Saturday, June 27, 2015 by ella

Chemistry Stoichiometry
The density of chloroform at a pressure of 220 mmHg and 25 degrees celsius is 1.42 g/L. Calculate the molar mass of chloroform. My set up is: mol*K .289 atm 1 1.42g/L ------------- ------------ ------ --------- .08206Latm 1 298K What I am unsure of is if this is the right way ...
Saturday, June 27, 2015 by Jack

Chemistry
If 100.0 mL of 0.150 M sodium nitrate is added to 50.0 mL of 0.150 M sodium carbonate, what is the resulting molar concentration of the sodium ion?
Friday, June 26, 2015 by John

Chemistry
How would I find the pH of these? I found it for d and e, but I don't know how to do the rest a) 0.25M carbonic acid b) 0.075M CN- c) 0.15M F- d) 0.015M HCl (I got 1.8) e) 0.015 M NaOH (I got 12) f) 0.050 M acetic acid
Thursday, June 25, 2015 by Sara

chemistry
How to distinguish between an acid and an alkali. DO not use indicators
Wednesday, June 24, 2015 by Clive

Chemistry
You may have noticed that when water boils, you can see bubbles that rise to the surface of the water. a. What is inside these bubbles? i. air ii. hydrogen and oxygen gas iii. oxygen gas iv. water gas v. carbon dioxide gas
Wednesday, June 24, 2015 by Anonymous

Chemistry
PCl5 is introduced into an evacuated chamber and comes to equilibrium (see Problem 16.37), at 250◦C and 2.00 atm. The equilibrium gas contains 40.7% Cl2 by volume. (a1) What are the partial pressures of the gaseous components at equilibrium? (a2) From these data, ...
Wednesday, June 24, 2015 by Joe johnson

Chemistry
My question is I need to change to symbol on sodium ion, \rm Na^+, followed by the formula of a sulfate ion, \rm SO_4{}^{2-} Its my first time in chemistry class.
Wednesday, June 24, 2015 by Zulema

Chemistry
You have two beakers, one filled to the 100 mL mark with sugar (mass of sugar 180.0 g) and the other filled to the 100 mL mark with water (m ass of water 100.0 g). You pour all the sugar and all the water together in a bigger beaker and stir until the sugar is completely ...
Wednesday, June 24, 2015 by Kristina

Chemistry
A solution contains 0.284 M sodium nitrite and 0.257 M nitrous acid. What is the pH of the solution?
Wednesday, June 24, 2015 by Glenna

Chemistry
How energy is needed to vaporize 100 g of ethanol from its boiling point?
Wednesday, June 24, 2015 by Joseph

Chemistry
Determine the molar solubility of Y for XY2 if Ksp is 2.2x10^-4 The answer is 0.038, but I'm not sure how
Wednesday, June 24, 2015 by Sara

Chemistry
Enter the symbol of a sodium ion, \rm Na^+, followed by the formula of a sulfate ion, \rm SO_4{}^{2-}
Wednesday, June 24, 2015 by Zulema

Chemistry
Electron configuration for phosphorus is 1s2 2s2 2p6 3s2 3p3. So the number of electron must be 15 , right ? But , what if m = 1 ? Does it effect the number of electron ?
Tuesday, June 23, 2015 by Lily

Chemistry
How mush CaCl2, in grams, is needed to make 2.0 L of a 3.5M solution? g CaCl2 = (2.0L) *( 3.5 mol Cl-/1L) * (1mol CaCl2/ 2mol Cl-) *( 110.98 g CaCl2/ 1 mol CaCl2) = 5.549 g CaCl2 i don't think i did any of this right
Tuesday, June 23, 2015 by Sydney

Chemistry
For this question, I know how to answer the first three questions, but not the rest. 12ml 0.025 M of benzoic acid (Ka=6.3x10-5)is titrated with 0.050 M NaOH. How many moles of benzoic acid are there? I got 0.0003 What volume of NaOH is required?(L) I got 0.006 What is the ...
Tuesday, June 23, 2015 by Sara

chemistry
find the numbers of elerctorins in 18ml water
Tuesday, June 23, 2015 by nikita bhukar

Chemistry
I have this question as a review question: The reaction N2(g)+3H2(g)<-->2NH3(g) begins with 1.15 M N2 and 1.36 M H2. At equilibrium, the concentration of NH3 is 0.78 M. Determine the extent of reaction. The answer is supposed to be 86 but I don't know how
Tuesday, June 23, 2015 by Sara

chemistry
. A student added 40.0 mL of an NaOH solution to 90.0 mL of 0.400 M HCl. The solution was then treated with an excess of nickel(II) nitrate, resulting in the formation of 1.06 g of Ni(OH)2 precipitate. Determine the concentration of the original NaOH solution.
Tuesday, June 23, 2015 by abdulaziz

chemistry
. A student added 40.0 mL of an NaOH solution to 90.0 mL of 0.400 M HCl. The solution was then treated with an excess of nickel(II) nitrate, resulting in the formation of 1.06 g of Ni(OH)2 precipitate. Determine the concentration of the original NaOH solution.
Tuesday, June 23, 2015 by abdulaziz

Chemistry
Calculate the molarity of a solution made by adding 33.4 mL of concentrated nitric acid (70.4 % by mass, density 1.42 g/mL) to some water in a volumetric flask, then adding water to the mark to make exactly 2000 mL of solution. (It is important to add concentrated acid or base...
Tuesday, June 23, 2015 by JO

college chemistry
When a solution containing 8.00 g NaOH in 50.0 g of water at 25 °C is added to a solution of 8.00 g of HCl in 250.0 g of water at 25 °C in a calorimeter, the temperature of the solution increases to 33.5 °C. Assuming that the specific heat heat of the solution is ...
Tuesday, June 23, 2015 by Karla

chemistry
find the valuv of element X wich atomic wait is 6.664.10-23 and it's 40kg atoms number
Monday, June 22, 2015 by nikita bhukar

chemistry
NUMBER of electorn in 18ml water (solidity is 1gm/ml)
Monday, June 22, 2015 by nikita bhukar

Organic Chemistry
1. Which of the following bonds is the strongest? a. F-F b. F-Cl c. F-Br d. F-I I think it's A because of the same atomic radius. Is that correct? Am I on the right track?
Monday, June 22, 2015 by Michelle

chemistry
*.How many grams of KCl would you need to add to 2 liters of water to make a .50 M solution?
Sunday, June 21, 2015 by tApAsh

Chemistry
A 1.50 L buffer solution is 0.250 mol L-1 in HF and 0.250 mol L-1 in NaF. Calculate the pH of the solution after the addition of 0.0500 moles of solid NaOH. Assume no volume change upon the addition of the base. The Ka for HF is 3.5 × 10-4. Thanks in advance!
Sunday, June 21, 2015 by B

Chemistry
How many grams of (Bef2) are present in 655ml of a 0.442 M solution of (BeF2) Please help
Sunday, June 21, 2015 by Ocean

Chemistry
What is the molarity of a solution that contains 2.17 moles of (SrCl2) in 2,660ml of solution? I know that the formula is molarity=moles/liters Liters=.2660
Sunday, June 21, 2015 by Ocean

Chemistry
How many grams of Fe(NO3)2 are present in 555mL of a 0.650 M solution of Fe(NO3)2?? I have no clue what to do??
Sunday, June 21, 2015 by Ocean

Chemistry
What mass of water has 6.70 x10^23 molecules? I keep getting 2.005e47 On my calculator but the answer key says 20 g . 6.70x10^23 molecuels *1 mol/6.02x10^23*18.02 g H2O /1 mol That's how I set it up.
Sunday, June 21, 2015 by sakura

Chemistry
What is the pH of a 0.40 mol L^-1 H2Se solution that has the stepwise dissociation constants Ka1 = 1.3 × 10^-4 and Ka2 = 1.0 x 10^-11 ? Thanks in advance
Sunday, June 21, 2015 by Elaina

Chemistry
How many grams of Fe(NO3)2 are present in 555mL of a 0.650 M solution of Fe(NO3)2?? I have no clue what to do??
Sunday, June 21, 2015 by Ocean

Chemistry
Baking soda consists mostly of a single chemical. Look up what it is, its molecular weight and density, and determine the number of moles used in this recipe. Give your answer in moles but do not include the units.
Saturday, June 20, 2015 by Diana Merritt

Dilsuknagar public school chemistry
Calculate the mass ,volume and number of molecules of hydrogen liberated when 198grams of zinc reacts with hydrochloric acid?
Saturday, June 20, 2015 by meghansh

Chemistry
The emission of high energy particles from the nucleus of an atom is called A. radioactivity B. electromagnetism C. transmutation D. radioactive dating I said A. as my answer. The definition of radioactivity is worded differently in my book though so I wanted to check if my ...
Saturday, June 20, 2015 by Neena

chemistry
a 2.00g sample of zinc metal is added to a calorimeter containing 150g of nitric acid solution initially at 20.0 degrees celsius . The temperature of the solution increased to 28.0 degrees celsius . Calculate the delta H of the reaction assuming that the specific heat capacity...
Saturday, June 20, 2015 by sami

chemistry
what concentration of nitrogen should be present in a glass of water at room temperature? assume a temperature of 29°C a total pressure of 1 atm
Saturday, June 20, 2015 by ashmit

chemistry
A sample of gas has an initial volume of 20.9 L at a pressure of 1.4 atm If the sample is compressed to a volume of 12.9 L: , what will its pressure be? (Assume constant temperature.) Thank you
Thursday, June 18, 2015 by ap

Chemistry
Ethanol is the active ingredient of alcoholic beverages. It is also s a possible replacement for gasoline. The complete combustion of ethanol forms carbon dioxide and water. CH3CH2OH + O2 => CO2 + H2O Balance the equation. What mass of carbon dioxide is formed by the ...
Thursday, June 18, 2015 by Priscilla

Chemistry
PLS HELP ME(1)Write a balanced equation in each case dilute hydrochloric reacts with[i]ZnCO3[ii]CuCO3 (2)Discuss how hydrocarbons contribute to the formation of ozone in the atmosphere.I'M CONFUSED I NEED HELP!
Thursday, June 18, 2015 by Anonymous

Chemistry
(1)Write a balanced equation in each case dilute htdrochloric reacts with[i]ZnCO3[ii]CuCO3 (2)Discuss how hydrocarbons contribute to the formation of ozone in the atmosphere
Thursday, June 18, 2015 by Tazannia Tennyson

chemistry
Imagine that you have an ideal gas in a 4.80L container, and that 2450 molecules of this gas collide with a square-inch area of the container at any given instant. If the volume is increased to 19.2L at constant temperature, how many collisions will occur per square inch of ...
Wednesday, June 17, 2015 by Alicia Estrada

Chemistry
Showing all calculations and specific references to the equipment needed, describe how to prepare 500mL 0.250mol/L potassium iodide(KI) solution.
Wednesday, June 17, 2015 by Robyn

Chemistry
A solution containing excess lead(ii) nitrate is reacted with 380.0ML of 0.250mol/L potassium iodide solution. A bright yellow Precipitate is of lead(ii) iodide is formed. Calculate the mass of lead (ii) iodide that should be formed. Pb(NO3)2+2KI-> 2KNO3+PbI2
Wednesday, June 17, 2015 by Robyn

physical science chemistry
If 25 cm^3 of the potassium hydroxide (KOH) solution was used to neutralise 35cm^3 hydrochloric (HCl)solution, determine the concentration of the hydrochloric acid solution. Thanks
Wednesday, June 17, 2015 by jonathan

science chemistry
Brandon prepares a potassium hydroxide solution (KOH) that he uses during a titration to determine the unknown concentration of a hydrochloric acid solution calculate the mass of potassium hydroxide that is need to prepare 250 cm^3 of a standard 0,125 mol.dm^-3 KOH solution.
Wednesday, June 17, 2015 by dennis

chemistry
the reaction contains initially 5 moles of CO and 2 moles of H2O.the volume is 1 litre.but at equilibrium it is 0.5 moles of h2o .then value of Kc for reaction is.
Wednesday, June 17, 2015 by khushbo

Chemistry
Guys. I have another chemistry question that I am unsure with. I would appreciate it if you could help me with working out. Thanks. A sample of ethane, C2H6, contains 9.6 * 10 ^ 22 atoms. How many mole of ethane is present in the sample? Why do I need to divide (9.6*10^22) by ...
Wednesday, June 17, 2015 by Mole help!

Chemistry
Hi guys. I cannot figure out how to do this question. Can you please do all the working out. Thanks How many moles of Al atoms are needed to combine with 1.58 mol of O atoms to make aluminum oxide, Al2O3?
Wednesday, June 17, 2015 by Gursimran

chemistry
What is the amount of water produced when 2gram of hydrogen is ignited with 8gram of oxygen
Wednesday, June 17, 2015 by Xaim

chemistry
The amount of carbon which when completely burnt in air,produces 100gram of carbon dioxide by weight is
Wednesday, June 17, 2015 by Xaim

chemistry
Which of the following numbers is most significant (a)2000 (b)2.00033 (c)6.67×10 (d)0.000122
Wednesday, June 17, 2015 by Xaim

chemistry
The total number of water molecules in 36gram of water is
Wednesday, June 17, 2015 by Xaim

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