Monday
July 25, 2016

Homework Help: Science: Chemistry

Recent Homework Questions About Chemistry

chemistry
In the gaseous phase PCl5 dissociates according to the following equilibrium: PCl5⇌PCl3+Cl2 and Kc=0.8 at 613K .Determine the equilibrium composition when 0.12 moles/L of the three compounds are mixed at 613K.
Sunday, July 10, 2016 by Anonymous

chemistry
100 mL of 0.05 M NH3 solution are added to 60 mL of a 0.1 M solution of the same compound.Determine the concentration of the final solution.
Sunday, July 10, 2016 by Anonymous

Chemistry
A 1.00 g sample of limestone is allowed to react with 100 cm^3 of 0.200 mol/dm^3 HCl. The excess acid required 24.8 cm^3 of 0.100 mol/dm^3 NaOH solution. Calculate the percentage of calcium carbonate in the limestone
Sunday, July 10, 2016 by Gary

Chemistry
Given the following three electron configurations: 1s2 2s2 2p5 How many core electrons does this element have? A. 4 B. 5 C. 9 D. 2
Sunday, July 10, 2016 by Megan

Chemistry
Which of the following atoms would have the highest first ionization energy? A. Li B. Be C. Na D. Mg
Sunday, July 10, 2016 by Megan

CHEMISTRY
A solution of a metal carbonate M2CO3, was prepared by dissolving 7.46 g of the anhydrous solid in water to give 1000cm^3 of solution. 25.0cm^3 of this solution reacted with 27.0cm^3 of 0.100 mol/dm^3 hydrochloric acid. Calculate the relative formula mass of M2CO3 and hence ...
Saturday, July 9, 2016 by DAVID

CHEMISTRY
A 1.575 g sample of ethanedioic acid crystals, H2C2O4. xH20 was dissolved in water and made up to 250cm^3 . One mole of the acid reacts with two moles of NaOH. In a titration, 25.0 cm^3 of this solution of acid reacted with exactly 15.6 cm^3 of 0.160 mol/ dm^3 NaOH. Calculate ...
Saturday, July 9, 2016 by Jack

chemistry
the standard enthalpy of formation, for HCOOH(l)is equal to the standard enthalpy for which reaction?
Saturday, July 9, 2016 by Achan

Chemistry
What is theoretical yield in grams of CO2 formed from reaction of 3.12g CS2 and 1.88g O2?
Friday, July 8, 2016 by Mariah

Chemistry
How many mol of hydrogen present in 16g methane
Friday, July 8, 2016 by Anonymous

Chemistry
Two closed vessels of equal volume both with pressure p1 and temperature t1 are connected to each other by tube with negligible volume. If the temperature maintained of both vessels is then changed to t1 and t2 respectively what is the pressure in the vessels?
Thursday, July 7, 2016 by Yuktee

chemistry
To 100 mL of a 0.1M NH3(Kb=1.8*10-5)solution,200mL of a 0.1M NaOH have been obtained.Calculate the pH of the solution.
Thursday, July 7, 2016 by Anonymous

science,physics,chemistry
According to our theory atomic size should increase in groups from top to bottom but in group 13 Aluminium has atomic radius 143 pm and Gallium has atomic radius 135 pm which is less WHY??????
Thursday, July 7, 2016 by Neh

Chemistry
What is the name for the following coordination compound or ion? Na3[Cr (NH3) NO2 Cl3]
Wednesday, July 6, 2016 by Katrina

Chemistry
In the reaction C + O2 → CO2, 18 g of carbon react with oxygen to produce 72 g of carbon dioxide. What mass of oxygen would be needed in the reaction?
Wednesday, July 6, 2016 by Kelly

chemistry
What is the difference between the acid and base notation of a hydroxide? Give an example of the same molecular formula written in acid and base notation.
Wednesday, July 6, 2016 by chris

Chemistry
The specific heat capacity of copper is 0.09 cal/g°C. How much energy is needed to flow into a 10-gram sample to change its temperature from 20°C to 21°C?
Wednesday, July 6, 2016 by Mariah

chemistry
How many grams of dipotassium succinate trihydrate (K2C4H4O4·3H2O, MW = 248.32 g/mol) must be added to 790.0 mL of a 0.0522 M succinic acid solution to produce a pH of 5.872? Succinic acid has pKa values of 4.207 (pKa1) and 5.636 (pKa2). is the pH of the current ...
Wednesday, July 6, 2016 by Melodie

Chemistry
For the following reaction, identify the substance being oxidized and reduced CH4 + 2 O2 = CO2 + 2 H2O
Wednesday, July 6, 2016 by Dylan

chemistry
How many g of H2 is formed from 2.4 g H20 according to the following reaction. 2H2O--->2H2O+O2 I believe the answer is .27g However, I can't understand how to work the problem completely out or one like it, if someone could please explain the formula it would be ...
Wednesday, July 6, 2016 by me

Chemistry
For the following reaction, how many kJ of heat are produceed in forming 225.0 g of NO? 4 NH3 + 5 O2 → 4 NO + 6 H2O ΔHrxn = -906 kJ/mole
Wednesday, July 6, 2016 by Morgan

Chemistry
If the ΔH for H2O(l) → H2O(s) is -6.01 kJ, then what is the ΔH for 2H2O(s) → 2H2O(l)? A -6.01 kJ B. 6.01 kJ C. -12.02 kJ D. 12.02 kJ
Wednesday, July 6, 2016 by Leanne

Chemistry
What is the oxidized substance in the following reaction? Fe + 2HCl → FeCl2 + H2
Wednesday, July 6, 2016 by Dylan

AP Chemistry
Q - An electrochemical reaction occurs between an unknown element and zinc. The half-cell reaction for the zinc is: Zn(s) → Zn2+(aq) + 2e− The cell potential for the reaction is Eºcell = 1.83 V. Is the reaction spontaneous or nonspontaneous? Explain. What is ...
Wednesday, July 6, 2016 by Jessica AP Chemistry

AP Chemistry
Q - Aluminum metal reacts with zinc(II) ion in an aqueous solution by the following half-cell reactions: Al(s) → Al3+(aq) + 3e− Zn2+(aq) + 2e− → Zn(s) Predict the potential of the cell under standard conditions. Predict whether the reaction will occur ...
Wednesday, July 6, 2016 by Jessica AP Chemistry

AP Chemistry
Sodium can be extracted by heating naturally occurring salt until it is molten. An electrochemical process is then used to extract the sodium. Cl2 is produced at the anode, and Na is collected at the cathode. Write the half-reactions that occur at the anode and the cathode. ...
Wednesday, July 6, 2016 by Jessica AP Chemistry

Analytical Chemistry
What volume, in liters, of 1.09 M KOH solution should be added to a 0.102 L solution containing 9.35 g of glutamic acid hydrochloride (Glu, FW = 183.59 g/mol; pKa1 = 2.23, pKa2 = 4.42, pKa3 = 9.95) to get to pH 10.26? Should I start with molar concentrations in the beginning (...
Tuesday, July 5, 2016 by R

Chemistry
What volume of each of the following bases will react completely with 25.00 mL of 0.200 M HCl? a) 0.100 M NaOH b)0.0500 M Sr(OH)2 c)0.250 M KOH please explain and show detail I'm so lost on this problem... thanks!
Tuesday, July 5, 2016 by Chantelle

AP Chemistry
Is determining the excess reactant and limiting reactant an important part of a synthesis reaction? Is it an important part of a decomposition reaction? Explain.
Tuesday, July 5, 2016 by Jessica AP Chemistry

AP Chemistry
Choose a chemical reaction involving two or more reactants. For this reaction, how do you determine which reactant or reactants are limiting? Explain.
Tuesday, July 5, 2016 by Jessica AP Chemistry

AP Chemistry
Suppose you designed an experiment in which you burned a known quantity of magnesium in air. You used the product to determine how many moles of oxygen would react with the known number of moles of magnesium. Why would burning magnesium in air cause a source of error for this ...
Tuesday, July 5, 2016 by Jessica AP Chemistry

Chemistry
What is the required volume of an acid to prepare 2 L of solution a 10% (v/v).
Tuesday, July 5, 2016 by Dylan

chemistry
0.01 mol of H2SO4 is present in its solution. Find the pH of the solution
Tuesday, July 5, 2016 by answer please

CHEMISTRY
What mass of sulphur must be burned to produce 64.0 tonnes of sulphur dioxide. . . So far, I have calculated the molecular mass of SO2( 64.1 ) . and then found out the number of moles of sulphur dioxide. ( 998.4) What to do now?
Tuesday, July 5, 2016 by Clive

chemistry
If potassium chlorate is 80 percent pure ,then 48gram of oxygen would produced from how many gram of potassiumchlorate
Tuesday, July 5, 2016 by biswamohan

chemistry
Decomposition of nitrogen pentoxide in ccl4
Tuesday, July 5, 2016 by viji

Chemistry 1111
To determine the molarity of NaOH solution, student took 3.5 g of KHP (KHP – Potassium hydrogen phthalate; Molar mass = 204.22 g/mol) and dissolved in 50 mL of water and titrated with the given unknown molarity NaOH solution loaded in burette. His burette volume read 1.85...
Tuesday, July 5, 2016 by Lowell

chemistry
0.02 Moles of HCl were added to a buffer solution, prepared by fluxing 20 L of gaseous NH3 and 10 L of gaseous HCl, both measured in normal conditions, in 2L of water. Calculate the pH of the solution before and after the HCl addition. (Kb NH3 = 1.8 * 10-5).
Tuesday, July 5, 2016 by Anonymous

chemistry
Calculate the pH of a solution containing 10 g / L of NH4Cl (Kb NH3 = 1.8x10-5
Tuesday, July 5, 2016 by Anonymous

chemistry
Decomposition of nitrogen pentoxide in ccl4
Tuesday, July 5, 2016 by viji

chemistry
To 100 mL of a 0.1M NH3(Kb=1.8*10-5)solution,200mL of a 0.1M NaOH have been obtained.
Tuesday, July 5, 2016 by Anonymous

chemistry
Determine the pH of a solution containing 1.00 mol/L of HCN (Ka = 5.00×10–10) and 5.00×10–2 mol/L of HCl.
Tuesday, July 5, 2016 by Anonymous

chemistry
Calculate the pH of a solution obtained dissolving 10 g of NH3 and 15 g of NH4Cl in 300 ml of water (Kb NH3 = 1.8 x10-5)
Tuesday, July 5, 2016 by Anonymous

AP Chemistry
The G value for formation of gaseous water at 298 K and 1 atm is -278 kJ/mol. What is the nature of the spontaneity of formation of gaseous water at these conditions?
Tuesday, July 5, 2016 by Jessica AP Chemistry

Chemistry
A 25g piece of an unknown metal alloy at 150 degrees Celsius is dropped into an insulated container with 200 g of ice. Calculate the specific heat capacity of the metal, given that 9.0 g of ice melted. How would you work this out?
Tuesday, July 5, 2016 by Fred

chemistry
Difference between a halogen and a halide? Explain using chemical formulas.
Tuesday, July 5, 2016 by lo

chemistry
Write the balanced chemical equation for the dissolution of magnesium sulphate
Monday, July 4, 2016 by lo

Chemistry
What is the volume in L of 34.0g of Ammonia (NH4) at STP?
Monday, July 4, 2016 by Joaquii

Chemistry
An element crystallizes in a body centered cubic unit cell. The radius of this element is 2.20A , and the density is .991 g/cm^3. how many moles of atoms are within one unit cell?
Sunday, July 3, 2016 by Lexi

chemistry
You need to make a 300 ml of a .37M Na2 SO4 solution. How much Na2 So4 should you weigh out?
Sunday, July 3, 2016 by mika

Chemistry
alculate the amount of energy released in the formation of one mole of MgSe bonds (not lattice energy). The radius of the magnesium ion is 0.65 Å, and the radius of the selenide ion is 1.98 Å. Note that 1Å=10−10m
Sunday, July 3, 2016 by Bob

Chemistry Help Please!
1) You have a protein at 20 ug/ml. Its MW =10,000. What is the concentration in molarity? Show work please! 2) You are asked to make 30 mL of a solution at 0.03M using the 0.10M stock solution. How many mililliliters of water do you use to make this solution? How many ...
Sunday, July 3, 2016 by Kimberly

CHEMISTRY
USING DOT (.) AND CROSS (x) DIAGRAM SHOW THE BONDING IN THE COMPOUND FORMED WHEN HYDROGEN AND OXYGEN COMBINE
Sunday, July 3, 2016 by STEPHEN

chemistry
Calculate number of electrons present in 9.5g of PO4^3-
Sunday, July 3, 2016 by vivek pathak

Chemistry
Calculate the molarity and normality of a solution made by dissolving 50g of Al(SO4)3 to produce 2.5 liter of solution.
Saturday, July 2, 2016 by Jonalyn

Chemistry
What is the kb of a 0.0200 m ( at equilibrium) solution of methyl amine, ch3nh2, that has a ph of 11.40?
Saturday, July 2, 2016 by Dylan

chemistry
Determine the pH of a solution containing 1.00 mol/L of HCN (Ka = 5.00×10–10) and 5.00×10–2 mol/L of HCl. It will be the best for me if you give me the answer of this problems.
Saturday, July 2, 2016 by Anonymous

chemistry
Calculate the pH of a solution obtained by mixing 50 mL of NH3 0.1 M (Kb = 1.8•10–5 mol/L) and 25 mL of HCl 0.2 M.
Saturday, July 2, 2016 by Anonymous

chemistry
Calculate the pH of 0.3 M HCl solution. Calculate the pH when 100 mL of a 0.5 M solution of NaOH are added to 300 mL of the HCl solution.
Saturday, July 2, 2016 by Anonymous

chemistry
Calculate the pH of a solution obtained by mixing of 100 mL of a 10-3 M and 50 mL of a 10-2 M solution of CH3COONa.
Saturday, July 2, 2016 by Anonymous

Chemistry
A 360mg sample of sugar (molar mass of 180 g/mol) is dissolved in enough water to produce 200mL of solution. after the sugar is completely dissolved, you pour 50mL of this solution into a Burnette for use in an experiment. what is the molar concentration of sugar in the sample
Saturday, July 2, 2016 by Jacke

chemistry
Arrange the following groups of atoms in order of their increasing atomic radius: K,Rb,F,B,Be I think its F<B<Be<K<Rb someone can you correct me pls
Friday, July 1, 2016 by lo

Chemistry
Ammonium phosphate and nickel(II) nitrate solutions are mixed, what precipitates out?
Friday, July 1, 2016 by Anonymous

Chemistry
When the equation below is balanced and all coefficients are in the lowest, whole number ratio, the coefficients are: C2H6 + O2 ¨ CO2 + H2O I am currently doing an online worksheet to improve in chemistry and I am not quite understanding how to find the coefficients ...
Friday, July 1, 2016 by Anonymous

Chemistry
When the equation below is balanced and all coefficients are in the lowest, whole number ratio, the coefficients are: Bi + O2 ¨ Bi2O3
Friday, July 1, 2016 by Anonymous

Chemistry
Calculate the normality of 1.5M sulphuric acid
Friday, July 1, 2016 by Nishu

chemistry
how do I prepare 10% HCL from 50% HCL solution
Friday, July 1, 2016 by slindile

Chemistry
Balance both the atoms and charges of the following chemical equation: Ce4+ + S2 −→ Ce3+ + S This is what I came up with: 3Ce4+ + S2 −→ 4Ce3+ + 2S
Friday, July 1, 2016 by Mariah

chemistry
60 cm of hydrogen diffused through a porous membrane in 10 minutes. The same volume of gas G diffused through the same membrane in 37.4 minutes. Determine the relative molecular mass of
Thursday, June 30, 2016 by emmanuel

Chemistry
Given the balanced neutralization equation: H2SO4+2KOH→K2SO4+2H2O How many moles of potassium hydroxide (KOH) are required to neutralize 4.5 mol of sulfuric acid (H2SO4)? Assume that the sulfuric acid completely dissociates in water. 2 mols of KOH = 1 mol of H2SO2 4.5 ...
Thursday, June 30, 2016 by Mariah

chemistry/biochemistry
How can we calculate the HCO3- (bicarbonate ion) concentration in water in 25C pH7.0? I think we can use PV=nRT equation, but I am not sure. If pH is changed from 7.5 to 6.5 ( around pka 6.3 of CO2), how can change the HCO3- concentration? Thanks in advance.
Thursday, June 30, 2016 by Anonymous

Chemistry
100g of water is added into 10.6m NaOH solution.What is the mol fraction of NaOH in the diluted NaOH solution. Density of NaOH is 1.08g/ml
Thursday, June 30, 2016 by Que

Chemistry
How to convert 1.08g/ml to volume in ml?
Thursday, June 30, 2016 by Que

Chemistry
What quantity of NaOH should be dissolved in 15000l of water to obtain 4% concentration? proposed solution 4/100 * 15000 = 600
Thursday, June 30, 2016 by Mankah

chemistry
2Na+(aq) + 2OH−(aq) + Zn2+(aq) + 2NO3−(aq) → Zn(OH)2(s) + 2Na+(aq) + 2NO3−(aq) Write the net ionic equation for this precipitation reaction.
Wednesday, June 29, 2016 by malka

Chemistry
What will the pH of a solution be when 0.5447 L of NaOH (pH = 14.436) is added to 0.357 L of 2.01 M ascorbic acid (H2C6H6O6)? Not sure how to do this.
Wednesday, June 29, 2016 by Anonymous

chemistry
How would prove that sodiumhydroxied is a base without using litmus paper to test
Wednesday, June 29, 2016 by marvelous

Chemistry
How would you find out whether a sample of sodium chloride is pure or impure
Wednesday, June 29, 2016 by Anand

University of Liberia Chemistry 102
Using a current of 4.75A how many minutes does it takes to plate onto a sculpture 1.50g of CuSO4 solution?
Wednesday, June 29, 2016 by James

chemistry
Calculate the amount of water (in grams) that must be added to 5.00 g urea in preparation of 16.2% by mass solution.
Tuesday, June 28, 2016 by ain

Chemistry
What is the variable x in the following hydrate formula NaCl xH2O if the mass of sodium chloride is 58g and the mass of the water is 36g
Tuesday, June 28, 2016 by Kim

chemistry plz helpp!
A) 9.8g of an alcohol A completely reacts with an excess of sodium , and a gas is released. When the reaction ceases the volume of the gas is 1.6L measured at a temperature of 22ºc and under a pressure of 1 bar.  a- What gas is released in this reaction, how can it ...
Tuesday, June 28, 2016 by angy

Chemistry
100 g of water is added into 10.6 m NaOH solution. The diluted NaOH solution is then neutralized completely with H2SO4 solution. Density of NaOH is 1.08 g/ml. Calculate: i. the mol fraction of NaOH in the diluted NaOH solution. ii. mol of H2SO4 required.
Tuesday, June 28, 2016 by Ann

chemistry
Calculate the amount of water (in grams) that must be added to 5.00 g urea in preparation of 16.2% by mass solution.
Tuesday, June 28, 2016 by baizura

Chemistry
100g of water is added into 10.6M NaOH solution. The diluted NaOH then neutralized completely with H2SO4 . density of NaOH is 1.08g/ml . calculate the mole fraction of NaOH in diluted solution .
Tuesday, June 28, 2016 by Amy

chemistry
A) 9.8g of an alcohol A completely reacts with an excess of sodium , and a gas is released. When the reaction ceases the volume of the gas is 1.6L measured at a temperature of 22ºc and under a pressure of 1 bar. a- What gas is released in this reaction, how can it be ...
Tuesday, June 28, 2016 by angy

chemistry
If 5.00g of glucose were to react completely with an excess of oxygen, how many grams of carbon dioxide would be produced?
Tuesday, June 28, 2016 by helena15zgeo

Chemistry
100g of water is added into 10.6M NaOH solution. The diluted NaOH then neutralized completely with H2SO4 . density of NaOH is 1.08g/ml . calculate the mole fraction of NaOH in diluted solution .
Tuesday, June 28, 2016 by Amy

Chemistry
The volume of 18 molar concentrated H2SO4 that must be diluted with distilled water to prepare 10 liters
Monday, June 27, 2016 by Angel Kenkpen

chemistry
sorry,for the mistake. To 200mL of a 0.1M solution of a CH3COOH (Ka=1.8 x 10-5) 70mL of a 0.2M solution of NaOH have been added.calculate the pH before and after the NaOH addition.
Monday, June 27, 2016 by Anonymous

chemistry
I am trying to calculate the how amount of Tris-bicarbonate should be added in the reaction. I would like to have final volume of bicarbonate 10mM in 2ml reaction. I made Tris-base (1M, 100ml) and instead of HCl, CO2 was bubbling to set pH7.5. 0.1L*0.1M= 0.01 moles of Tris &#...
Monday, June 27, 2016 by chocho

chemistry
How could you prepare: a ) 2-chloropropane from 2-propanol? b) 2-butanone from 2-butanol? c) ethyl acetate CH3COOC2H5 from ethanol? d) 2-methyl-2-butene from 3-methyl-2-butanol?
Monday, June 27, 2016 by vicky

Organic Chemistry
Suppose 5.00 gram of a mixture of aspirin, caffeine, and acetanilide was dissolved in enough solvent (methylene chloride) to make a total of 100.00 mL volume. You took 10.00 mL from it and isolated its components using the same protocol you did in the lab. You obtained: ...
Monday, June 27, 2016 by David

Chemistry
I had to do a lab and had to calculate the molar mass for a substance with this equation MM=Mrt/pv but we had to calculate the mass of the substance and its temperature experimently. My question is why did we have to boil the liquide in a water containing becker. Why did we ...
Monday, June 27, 2016 by Gabby

chemistry
write the electron-dot formula for the following compound HCN,Co2,H2O@,O2,H2O
Monday, June 27, 2016 by maawiya muhammad diggie

Chemistry
Hi I got a question if we have An unknow but we have its molecular formula of that unknown compound can that Molecular formula ALWAYS tell us exactly what compound we have?
Monday, June 27, 2016 by Bonny

Chemistry
What is the amount of oxygen needed to create output 20gm?
Monday, June 27, 2016 by LABIBUL HASAN

Chemistry
Sorry, I have been stuck on this question. I would appreciate if someone could help me out. Approx how many mL of 0.25M BaCl2 solution would be required to precipitate all the sulfate if we assume the sample is pure sodium sulfate? Assume that the density of the barium ...
Sunday, June 26, 2016 by Mike

chemistry
How many degenerate orbitals have the following name? 2s 3p 5d 4p 5s I dont get this question
Sunday, June 26, 2016 by lo

Chemistry
The sulfate in a 0.2345 g sample of a mixture containing only K2SO4 (fm = 174.26) and Na2SO4 (fm = 142.04) is to beanalyzed by precipitating all the sulfate as barium sulfate, BaSO4 (fm = 233.39) by the addition of excess BaCl2. Na2SO4 + BaCl2 image from custom entry ...
Sunday, June 26, 2016 by Esraa

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Homework Help: Science