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March 29, 2017

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Homework Help: Science: Chemistry

Recent Homework Questions About Chemistry

Chemistry
Please help! I'm trying to find the solubility of Ca(OH)2 in .001305 mol/L aqueous NaOH? Saturated solution of Ca(OH)2 in 0.01305 mol/L NaOH. [HCl] = 0.1213 M Volume of HCl = 9.81 mL Volume of Ca(OH)2/NaOH aliquot = 25ml Find: 1. the TOTAL [OH-] in the saturated solution of Ca...
Monday, March 20, 2017 by Alex

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 = 4 to the level n = 1.v
Monday, March 20, 2017 by Anonymous

Chemistry
You need to make 40.00 ml of a 0.045M NaOH solution from a 2.1M stock solution. How many ml of the stock solution are needed?
Sunday, March 19, 2017 by Kailee

Chemistry
A solution of a weak acid (.025M, 200ml) is mixed with a solution of NaOH ( 0.015M, 150ml). The equilibrium pH is 5.51. What is the Ka of the weak acid?
Sunday, March 19, 2017 by Jae M.

chemistry
What would the predicted voltage be if four Zn(s)/ Zn2+(aq) // Ag+(aq) / C (s) cells were connected in series
Sunday, March 19, 2017 by Kelsey

A.P Chemistry
For a certain reaction ∆H is 54 kJ/mol and ∆S is 128 J/mol · K. This reaction can become spontaneous only above some temperature. What is this temperature? Answer in units of ◦C.
Sunday, March 19, 2017 by Rachel

Chemistry
How did the net voltage of the two cells connected in series compare to the net voltage of a single why the calculated cell potentials and the observed cell potentials might be different
Sunday, March 19, 2017 by Kelsey

chemistry
consider equilibrium equation below `Mg(NO3)2(aq) + 2Na(OH)(aq) <--> Mg(OH)2(s) + 2NaNO3 (aq) If NH3 is added, according to Le Chatelier's Principle, which way would reaction shift?
Sunday, March 19, 2017 by sam

Reposting Chemistry Question -Emergency !!
Saturated solution of Ca(OH)2 in 0.05349 mol/L NaOH. Temperature: 22.1 * C Volume of Ca(OH)2/NaOH aliquot: 25ml Concentration of Standard HCl: 0.1213M Indicator Used: Bromothymol Blue Ksp from previous part I got 3.55x10^-5 - Average volume of HCl added to titrate was 15.05 mL...
Sunday, March 19, 2017 by DrBobPleaseHelp

Chemistry
How many moles of magnesium nitride form when 1.0 mole of magnesium reacts completely?
Sunday, March 19, 2017 by Carly

Chemistry
Determine the pH at the equivalence point when 25.00 mL of 0.1056 M CH3COOH is titrated with 0.1056 M NaOH.
Sunday, March 19, 2017 by Help101

Chemistry Explanation??
So what would the explanation for this be? Its really confusing me. The Ksp is independent of [NaOH] while the solubility of Ca(OH)2 decreases as the [NaOH] increases. Explain why this is the case. ( in the data table, the naoh concentration is 0 M, and the solubility is 2.30 ...
Sunday, March 19, 2017 by Help101

Chemistry
what is the oxidation number of Carbon in C6H12? thank you!
Sunday, March 19, 2017 by Jake

Chemistry 2202
Henry uses 0.150L of 0.500 mol/L NaOH to neutralize 250.0 mL of the hydrochloric acid. What is the concentration of the HCl (aq)?
Sunday, March 19, 2017 by Hannah

Chemistry
An empty aerosol-spray can at room temperature (20 ◦C) is thrown into an incinerator where the temperature reaches 458◦C. If the gas inside the empty container was initially at a pressure of 1 atm, what pressure did it reach inside the incinerator? Assume the gas was at ...
Sunday, March 19, 2017 by Madi

chemistry
. What is the pH of a solution in which 15 mL of 0.10 M NaOH is added to 25 mL of 0.10 M HCl?
Sunday, March 19, 2017 by Anonymous

chemistry
calculate the mass at 15.0 L at NH3 at 27 digree Celsius and 900 mm hg?
Sunday, March 19, 2017 by Tshering

physical chemistry
a mixture of toluene and water boils at 90 degrees. calculate the vapour pressure at this temperature. Assume the atmospheric pressure to be 760 mmHg
Sunday, March 19, 2017 by joyce

Chemistry
How many joules are required to raise the temperature of 450mL of water from 30 °C to 100 °C? The specific heat of copper metal is 0.385 J/ g- K. How many KJ of heat needed to raise the temperature of 1.1 kg block of copper from 27.5 C to 50 C? If 200 J of heats is added to...
Sunday, March 19, 2017 by Jenner

chemistry
The specific heat of copper metal is 0.385 J/ g- K. How many KJ of heat needed to raise the temperature of 1.1 kg block of copper from 27.5 C to 50 C?
Sunday, March 19, 2017 by kathryn

Chemistry
What mass of ammonia is necessary to produce 500 kJ of heat? 4 NH3(g) + 5 O2(g) → 4 NO(g) + 6 H2O(g) ΔrH = -906 kJ mol-1
Saturday, March 18, 2017 by Anonymous

Chemistry
The enthalpy of combustion of butane C4H10 is described by the reaction: C4H10(g) + (13/2) O2(g) -> 4CO2(g) + 5H2O(g) ΔH°rxn = –2613 kJ/mol Given the following enthalpies of formation: ΔH°f[CO2(g)] = -393.5 kJ/mol ΔH°f[H2O(g)] = -241.8 kJ/mol Calculate the value of ...
Saturday, March 18, 2017 by anon

Chemistry
1)What is the pH of a 0.25 M solution of acetate (CH3COO-) with a pKa of 4.76? 2)If the [OH] of a solution is 2.95 x 10-5M, what is the pH of the solution? 3)Determine the pH at the equivalence point when 25.00 mL of 0.1056 M CH3COOH is titrated with 0.1056 M NaOH. 4)Determine...
Saturday, March 18, 2017 by ChemEmergency

Chemistry Titration-emergency :(
[HCl]=0.1213M Avg Amount HCl added: 14.15mL Volume of Saturated Solution of Ca(OH)2 in NaOH used: 25 mL and its concentration was 0.05349 M. 1.)Calculate the total [OH ] in the saturated solution of Ca(OH)2 in sodium hydroxide -> for this do I only find the mols of HCl? and...
Saturday, March 18, 2017 by DrBobPleaseHelp

Chemistry
c) Now make up 500 mL of a 0.025M phosphate buffer using the 0.1M phosphate buffer. Show all your workings. The 0.1M is made of 120.1ml conjugate base and 379.9ml acid.
Saturday, March 18, 2017 by LQ

Chemistry
c) Now make up 500 mL of a 0.025M phosphate buffer using the 0.1M phosphate buffer. Show all your workings. The 0.1M is made of 120.1ml conjugate base and 379.9ml acid.
Saturday, March 18, 2017 by LQ

chemistry
Under the same condition temperature and pressure hydrogen diffuses 8 times as fast as gas y calculate the rmm of gas y the rmm of h=2
Saturday, March 18, 2017 by Anonymous

Chemistry
Determine the final temperature of water if 17.6 kJ of heat is added to 350 g of water initially at a temperature of 24.10 C. (specific heat of water is 4.184 Jg^-1K^-1)
Saturday, March 18, 2017 by Anonomous

Chemistry
Calculate the tota bond energy of ethanol from this info:(C_C=347,C_H=414,H_O=464,C_O=360)kJ​mol-1.Thanks for responding
Saturday, March 18, 2017 by Jonathan

chemistry
according to the data in the merck index,if 1,0g of aspirin is dissolved in 100ml of water at 37,how much aspirin will precipitate out of solution when it is cooled to 25.
Saturday, March 18, 2017 by peter

Chemistry
Given below is a reaction 2Mg+O2 = 2MgO Mass of magnesium oxide formed by buring 24g of magnesium in air is a.16g b.80g c.20g d.40g
Saturday, March 18, 2017 by Rashi

chemistry
Calculate the pH of a buffer solution prepared by mixing equal volumes of 0.20 M NaHCO3 and 0.10 M Na2CO3. (Ka = 4.3 x10-7)
Friday, March 17, 2017 by Anonymous

Chemistry
What is the final temperature when 180.0 mL water at 101.3 C is added to 93.1 mL of water at 65.5 C?
Friday, March 17, 2017 by Anon

Chemistry
A gas expands its volume from 4.7 L to 8.9 L at constant temperature. Answer the following: a) If the gas expands against vacuum conditions, calculate the work (in joules) done by the gas. b) Calculate the work done (in joules) by the gas if it expands against a constant ...
Friday, March 17, 2017 by Anon

Chemistry
Which equation would describe the following equilibrium constant? Kc = [Bi3+]2[S2-]3 ----- Bi2S3 (s) <-> 2Bi3+ (aq) + 3S2- (aq) Bi2S3 (s) + 6HCl (aq) <-> 2BiCl3 (aq) + 3H2S (aq) BiS (s) <-> Bi3+ (aq) + S2- (aq) Bi2S3 (s) <-> 3Bi2+ (aq) + 2S- (aq)
Friday, March 17, 2017 by nonny

chemistry
when hcl reacts with mg, how many grams of magnesium are needed to produce 100 grams of hydrogen?
Friday, March 17, 2017 by tehreem

Chemistry
Determine the pH of a solution after 20.00 mL of 0.4963 M HI has been titrated with 12.64 mL of 0.5174 M NaOH.
Friday, March 17, 2017 by Sarah

Chemistry
Determine the number of moles of NaCl in the solution. Measured Mass of NaCl: 11.69g Measured Vol of Water: 100mL Molar Mass of NaCL: 58.44g/mol 11.69gNaCL/58.44g/mol = 0.20 mol NaCl Do I then to multiply my answer by 100ml? 0.20 x 100=20.00mol NaCl?
Thursday, March 16, 2017 by Rose

chemistry
Calculate the mass of benzoic acid required to prepare 100cm3 each of 0.1m,0.25m, and 0.5m solutions
Thursday, March 16, 2017 by elamin

Chemistry
Consider the titration of 20.00 mL of 0.1728 M Ascorbic acid (Ka = 7.9 x 10-5) with 0.4329 M NaOH. Match the following regions in the titration curve with the appropriate pH range. 1.Initial pH 2.Before equivalence point 3.At equivalence point 4.After equivalence point A. 8 - ...
Thursday, March 16, 2017 by Sarah

Chemistry
Determine the pH of a solution after 20.00 mL of 0.4963 M HI has been titrated with 12.64 mL of 0.5174 M NaOH.
Thursday, March 16, 2017 by Sarah

chemistry
When a base is introduced into this buffer, which of H2CO3 and HCO3− reacts with the base to maintain the pH of the solution? HCO3− H2CO3
Thursday, March 16, 2017 by Jennifer

Chemistry
you have a solution of 0.1 m KCN and a solution of 0.1 m of HF what is the buffer?
Thursday, March 16, 2017 by Jennifer

Chemistry
You dissolve 2.35 g of sodium carbonate (Na2CO3) in sufficient water to produce a final solution volume of 100.0 mL. Assuming all of the solid dissolves, calculate the solution pH.
Thursday, March 16, 2017 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
Thursday, March 16, 2017 by Driyah

organic chemistry
2. An unknown white solid has melting point range 119 – 121o C. Benzoic acid is a white solid of 122 o C melting point. How can a student confirm the identity of the unknown solid (is the benzoic acid or not)
Thursday, March 16, 2017 by fatma

chemISTRY
What is the rms speed of N2 molecules at 281 K? What is the rms speed of He atoms at 281 K? where R=8.314
Wednesday, March 15, 2017 by Hannah

CHEMISTRY
If He(g) has an average kinetic energy of 4190 J/mol under certain conditions, what is the root mean square speed of Cl2(g) molecules under the same conditions?
Wednesday, March 15, 2017 by Hannah

chemISTRY
Under identical conditions, separate samples of O2 and an unknown gas were allowed to effuse through identical membranes simultaneously. After a certain amount of time, it was found that 5.36 mL of O2 had passed through the membrane, but only 3.60 mL of of the unknown gas had ...
Wednesday, March 15, 2017 by Hannah

Chemistry help!!
Phosphoric acid, H3PO4, has some important applications. It can be used to produce fertilizers and it is present in soft drinks. Phosphoric acid can be made from phosphorus in a two step process: Reaction 1: P4 + 5 O2 --> P4O10 Reaction 2: P4H10 + 6H2O--> 4H3PO4 A ...
Wednesday, March 15, 2017 by Lyndsay

chemistry
A 275 mL sample of 1-propylamine vapor (in equilibrium with the liquid) at 25 °C is removed and dissolved in 0.500 L of H2O. For 1-propylamine, Kb = 3.72 x 10-4 and the vapor pressure at 25.0 °C is 316 Torr. a. What should be the pH of the aqueous solution? b. How many ...
Wednesday, March 15, 2017 by Andreea Grigore

CHEMISTRY
WHY A CONICAL FLASK CONTAINING A HOT SOLUTION IS NOT TIGHTLY STOPPERED TO PREVENT SOLVENT LOSS DURING COOOLING.
Wednesday, March 15, 2017 by CYNTHIA

Chemistry
When 22.50 mL of 0.500 M H2SO4 is added to 22.50 mL of 1.00 M KOH in a coffee-cup calorimeter at 23.50°C, the temperature rises to 30.17°C. Calculate ΔH of this reaction. (Assume that the total volume is the sum of the individual volumes and that the density and specific ...
Wednesday, March 15, 2017 by Beth

Organic Chemistry
What is the literature value for the partition coefficient for caffeine?
Wednesday, March 15, 2017 by Mark

Chemistry 11
What mass of iron can be obtained from 500.0g of Fe3O4? I am having a hard time getting started on this question. I think I need to find the percent of iron in the compound and then multiply that by 500.0 g. But, when I tried that I got a really wonky answer. Fe 3 55.85g/mol...
Wednesday, March 15, 2017 by Karen Zhang

Chemistry
When iron metal reacts with oxygen, the reaction can form Fe2o3 (numbers are subscripts). Write a balanced chemical equation for this reaction and find the number of moles of oxygen that are needed to form 6 mol of Fe2o3. Show your work. I am really stuck and I don't know how ...
Tuesday, March 14, 2017 by Leon

Chemistry
Please help me these are the only two I have left. 17. If the solubility of a gas is 5.6 g/L at 505 kPa pressure, what is the solubility of the gas when the pressure is 1010kPa? * 19. Calculate the [H⁺] for the aqueous solution in which [OH⁻] is 1 x10⁻⁹. Is this ...
Tuesday, March 14, 2017 by Lydia

chemistry
1.2 mol HCl and 3.9 mol NaOH react to this equation, HCl + NaOH=NaCl + H20 If the limited reactant id HCl, calculate the amount of NaCl formed in moles. Please help and explain how to solve this so I may understand it better please and thank you.
Tuesday, March 14, 2017 by Javier

Chemistry
How many grams of KI must be added to a 250-ml volumetric flask to prepare a water solution that is 0.100 M in potassium iodide?
Tuesday, March 14, 2017 by Miranda

Chemistry
When a 6.50g sample of solid sodium hydroxide dissolves in 100.0g of water in a coffee cup calorimeter, the temperature rises from 21.6C to 37.8C. A.) Calculate the quantity of heat (in kJ) released in the reaction. (I know the answer, but can you show the steps) Thanks
Tuesday, March 14, 2017 by Audrey

Chemistry
A 14.7 mL sample of 0.0550 M KOH solution required 55.5 mL of aqueous acetic acid solution in a titration experiment. Calculate the molarity of the acetic acid solution.
Tuesday, March 14, 2017 by Lane

Chemistry
By titration, 66.6 mL of aqueous H2SO4 neutralized 11.4 mL of 0.465 M LiOH solution. What was the molarity of the aqueous acid solution?
Tuesday, March 14, 2017 by Lane

Chemistry
Which elements have the greatest tendency to act as reducing agents? metals nonmetals noble gases halogens
Tuesday, March 14, 2017 by M, S, E

chemistry
How can lime be used yo improve the quality of soil degraded by industrial pollution?
Tuesday, March 14, 2017 by martha

chemistry
What will be the color of litmus paper when tested with lime?
Tuesday, March 14, 2017 by martha

chemistry
What is the name of the acid produced when CO2 reacts with water?
Tuesday, March 14, 2017 by martha

chemistry
What is the gas produced when lime is heated?
Tuesday, March 14, 2017 by martha

chemistry
How does ammonium ion act as an acid in the reaction between ammonium ion and water?
Tuesday, March 14, 2017 by martha

chemistry
What is the balanced equation of the reaction between ammonium ion amd water?
Tuesday, March 14, 2017 by martha

chemistry
What is the difference between the reaction of hydrochloric acid and water amd ethanoic acid and water?
Tuesday, March 14, 2017 by martha

chemistry
What os the balanced equation for the reaction between ethanoic acid and water?
Tuesday, March 14, 2017 by martha

chemistry
What is the balanced equation for reaction between hydrochloric acid and water?
Tuesday, March 14, 2017 by martha

chemistry
A titration to standardize a HCl solution was performed by taking 50.0ml hydrochloric acid in a flask with a few drops of phenolphthalein indicator. The burette was filled with 0.15 molar NaOH. The initial reading of the burette was 0.50ml and the final reading was 30.5ml. ...
Tuesday, March 14, 2017 by martha

chemistry
A 20ml hydrochloric acid is diluted by 80ml of distilled water, what would be the pH of the hydrochloric acid after the dilution?
Tuesday, March 14, 2017 by martha

chemistry
What will be the pH of hydrochloric acid after 0.01M of hydrochloric acid is diluted by the addition of 80ml distilled water?
Tuesday, March 14, 2017 by martha

Chemistry
in a neutralization reaction, dilute tetraoxosulphate (vi) acid completely reacted with sodium hydroxide solution.write a balanced chemical equation for the reaction
Tuesday, March 14, 2017 by Donniceski

Chemistry
The volume equivalent of CO2(at stp) in the reaction. NaHCO3+HCL=NaCL+H20+CO2 is
Tuesday, March 14, 2017 by Mihir

Chemistry
The volume equivalent of CO2(at stp)in the reaction NaHCO3+HCL=NaCL+H2O+CO2 is
Tuesday, March 14, 2017 by Mihir

Chemistry help!!
Potassium perchlorate decomposes as follows: KClO4 (s) --> KCl (s) + 2 O2 (g) If 269 mL of wet O2 (g) is collected over water at 25 c (vapor pressure= 23.8 torr) and the barometric pressure is 748.0 torr, how many grams of potassium perchlorate have decomposed?
Monday, March 13, 2017 by Lyndsay

Chemistry
Potassium perchlorate decomposes as follows: KClO4 (s) --> KCl (s) + 2 O2 (g) If 269 mL of wet O2 (g) is collected over water at 25 c (vapor pressure= 23.8 torr) and the barometric pressure is 748.0 torr, how many grams of potassium perchlorate have decomposed?
Monday, March 13, 2017 by Lyndsay

Chemistry
A tablet containing calcium carbonate and fillers with a mass of 1.631 g was dissolved in HCl. After the fillers were filtered out, the HCl was neutralized by adding sodium carbonate. The resulting precipitate was pure calcium carbonate (with the fillers removed). The solid ...
Monday, March 13, 2017 by Sam

Chemistry
A tablet containing calcium carbonate and fillers with a mass of 1.631 g was dissolved in HCl. After the fillers were filtered out, the HCl was neutralized by adding sodium carbonate. The resulting precipitate was pure calcium carbonate (with the fillers removed). The solid ...
Monday, March 13, 2017 by Erin

Chemistry
Can someone check my answer and let me know me if the are right or wrong. 1. What is the maximum amount of KCl that can dissolve in 600 g of water? (The solubility of KCl is 34 g/100 g H₂O at 20°C.) * 34 g 204 g ***** 2040 g 3. (1 point) If the solubility of a gas in water ...
Monday, March 13, 2017 by Lydia

chemistry
This refers to your archive question in 2014 Oct 30 at 4.58 posted by Ruzzle and replied by DrBob222. Small query on the solution , which states 1/6 of D atoms will go to form D2O18. Isn't it 2/6 since out of all 6 D atoms 2 is required to form D2O18. Please clarify. Regards ...
Monday, March 13, 2017 by senaka

chemistry
When a 8.45-mg sample of a compound containing carbon is burned completely, 18.1 mg of carbon dioxide is produced. What is the mass percentage of carbon in the compound?
Sunday, March 12, 2017 by kai

Chemistry
If 50.00 mL of 0.250 M barium nitrate are combined with 50.00 mL of 0.400 M sodium sulfate, how any grams of precipitate will form? I'd really appreciate it if someone could walk me through this problem. I don't want the answer, I just want to have a hint at which steps I need...
Sunday, March 12, 2017 by Matthew

Chemistry
Human blood contains glucose at a typical concentration of 0.100% (W/V). At this concentration, how many grams of glucose would be found in one liter of human blood?
Sunday, March 12, 2017 by Tammy

chemistry
Calculate the amount of silver deposited at cathod when 5 ampere of current is passed for 50 minutes through a solution of AgNO3
Sunday, March 12, 2017 by ali

chemistry
what is the method to prepartion CO from these equation in the lab CaCo3 + 2HCl → CaCl2+H2O+ CO2 (g) Or CaCo3 ----(Heat 500 to 600 C0→ Cao +Co2 (g) 2- CO2 + H2 → CO (s) + H2O(g) i have CaCo3 powder and i do not have any idea how to work in lab??? method???
Sunday, March 12, 2017 by roro

Chemistry
Convert the information described below into balanced equation: (a) When a mixture of copper(II) oxide and carbon is heated, elemental copper forms and carbon monoxide evolves into the atmosphere. (b) When a concentrated solution of sodium hydroxide is added to an aqueous ...
Sunday, March 12, 2017 by Dan

chemistry
how to prepare CO from this equation in the lab CaCo3 + 2HCl → CaCl2+H2O+ CO2 (g) Or CaCo3 ----(Heat 500 to 600 C0→ Cao +Co2 (g) 2- CO2 + H2 → CO (s) + H2O(g)
Sunday, March 12, 2017 by roro

Chemistry
A 6.3 g sample of solid NH4NO3 is dissolved in 50g of water, causing the temperature to drop from 24°C to 19°C. Calculate the ∆Hsolution in J/mol. -Thank you ☺
Sunday, March 12, 2017 by Gennelle

Chemistry
The specific heat of a copper metal is 0.385J/g-°K. How many kJ of heat are needed to raise the temperatue of 1.1 kg block of copper from 27.5°C to 50°C? -Thank you ☺
Sunday, March 12, 2017 by Gennelle

chemistry
Water, compared to other substances, has one of the highest specific heat values. What is the advantage of this fact for the human body? -Thank you ☺
Sunday, March 12, 2017 by Gennelle

Chemistry
Determine the Enthalpy of combustion of ethyne (C2H2) using the following enthalpies of formation; Data: DHf°(H2O)= -285.9kj/mol DHf°(2H2)= +226.7Kj/mol DHf°(CO2)= -393.5Kj/mol Equation; C2H2--------->CO2 + H2O
Sunday, March 12, 2017 by Steve

Chemistry
Write a balanced equation for the reaction that occurs in each of the following cases. (Use the lowest possible coefficients. Include states-of-matter under SATP conditions in your answer.) I think have the reactions, but I'm stuck with the states of matter. Any help would be ...
Saturday, March 11, 2017 by AC

Chemistry
In a titration experiment what would be the result on the concentration of the analyte if the drop counter did not count all the drops? would it be lower since you would just be calculating the concentration at the same point on the curve just with a lower volume of titrant?
Saturday, March 11, 2017 by Sean

Chemistry
Which statement is always true if ΔU sys is always negative? a) q = w b) +q>–w c) -w> +q d) +w>-q
Saturday, March 11, 2017 by Anon

Chemistry
Identify which of the following changes is exothermic. a) liquid water boils to steam b) liquid water freezes to give ice c) ice melts to give liquid water d) liquid water increases in temperature from 35 C to 45 C
Saturday, March 11, 2017 by Anon

Chemistry
what volume of oxygen is needed to react to complete reaction and to form 5cm of so3?
Saturday, March 11, 2017 by Anon

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