Sunday
July 5, 2015

Homework Help: Science: Chemistry

Recent Homework Questions About Chemistry

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

Chemistry
I have know clue how to answer this, but I tried something.(predicting products of electrolysis in aqueous solution)/ Predict the products of the electrolysis of a solution of aqueous MnSO4. I first wrote this: Mn^2+ SO4^2- Then for Mn^2+, it can be reduced to Mg(s) -2.36V and...
Tuesday, June 16, 2015 by Sara

Chemistry
Use each equation to predict whether the relative entropy change is S(products) > S(reactants) or S(products) < S(reactants) and whether ΔS > 0 or ΔS < 0 for the chemical reaction represented. Justify your answer in each case. a. 2NH3(g)&...
Tuesday, June 16, 2015 by Madison

college chemistry
Calculate the molarity (M) of 156.2g of H2SO4 in 1.275L of solution.
Tuesday, June 16, 2015 by Alicia Estrada

chemistry
A lactic acid/lactate ion buffer solution contains 0.43M HC3H5O3 and 0.90M C3H5O3-. The value of lactic acid is 1.4*10-4 calculate the pH of this buffer
Tuesday, June 16, 2015 by jennifer

Chemistry
Calculate the mass percent of a NaCl solution in which 158g of NaCl is dissolved in 3.81L of water at 25 ∘C (density = 0.997 g/mL).
Tuesday, June 16, 2015 by Alicia Estrada

Chemistry.
Predict these reaction products. If a reaction takes place, balance the reaction if needed. If no reaction takes place then write no reaction. Cu+FeCl3--->CuCl3 + Fe Double replacement Al+HBr----> AgNO3 + KCL--->AgClKnO3 Double replacement Ba(NO3)2+MgSO4---->BaSO4(...
Tuesday, June 16, 2015 by Jessy

Chemistry
Consider the NiCd (nickle cadmium) cell found in rechargeable batteries. 1.)Which element is the cathode when the cell is recharging (being electrolytic)? 2.)How many cells must be present to produce 1.2 V 3.)Which element is the anode when the cell is discharging (being ...
Tuesday, June 16, 2015 by Sara

Chemistry
Predict the products of the electrolysis of a solution of aqueous MnSO4 given the following choices: a. H2SO3 (aq) b. O2 (g) c. H2 (g) d. OH- (aq) e. Mn (s) f. e- g. H+ (aq) how is the answer O2 and H2SO3?
Tuesday, June 16, 2015 by Sara

chemistry
How many equivalents of an acid or base are in the following? 0.43mol Mg(OH)2 and 2.8g Mg(OH)2?
Tuesday, June 16, 2015 by jennifer

chemistry
What volume of 0.076M HNO3 is required to titrate 20.0ML of 0.25M Ba(OH)2 solution? use 2 sig figures
Tuesday, June 16, 2015 by jennifer

chemistry
The mechanism of solubility depends on the solute and solvent. Describe on an ionic or molecular scale how each of the following dissolve: a.NaCl in H2O b.I2 in CCl4 c.CH3CH2OH in H2O
Tuesday, June 16, 2015 by Lisa

chemistry
The ksp for Al(OH)3 is 3.7*-5 at 20 degrees. What is the solubility of Al(OH)3 in grams per litre?
Tuesday, June 16, 2015 by Lisa

chemistry
The concentration of Mg2+ ion in a solution is 0.010M. At what pH will Mg(OH)2 first precipitate? (Given Ksp Mg(OH)2 equals 1.2*10-11)
Tuesday, June 16, 2015 by Lisa

chemistry
Ksp fo CaSO4 is 6.1*10?-5. how many grams of CaCl2 must be added to 500ml of 0.010M H2SO4 to just start preciptation of CaSO4? I cant figure this out at all.
Tuesday, June 16, 2015 by Samantha

Chemistry
Equilibrium constants at 25 ∘C are Substance Kc Value of Kc CaCO3 Ksp 4.5×10−9 H2CO3 Ka1 4.3×10−7 Ka2 5.6×10−11 What is the molar solubility of marble (i.e., [Ca2+] in a saturated solution) in acid rainwater, for which pH=4.20?
Tuesday, June 16, 2015 by Samantha

chemistry
The molar volume of an ideal gas is
Tuesday, June 16, 2015 by Xaim

Chemistry
Item 1 Maleic acid is a carbon-hydrogen-oxygen compound used in dyeing and finishing fabrics and as a preservative of oils and fats. •In a combustion analysis, a 1.054-g sample of maleic acid yields 1.599 g of CO2 and 0.327 g of H2O. •When 0.609 g of maleic acid is ...
Tuesday, June 16, 2015 by Samantha

Chemistry
What is the pH change of a 0.220M solution of citric acid (pKa=4.77) if citrate is added to a concentration of 0.155M with no change in volume?
Tuesday, June 16, 2015 by Samantha

analytical chemistry
a buffer solution is 0.2M in acetic acid and in sodium acetate. Calculate the change in pH upon adding 1.0ml of 0.1M hydrochloric acid to 10ml of this solution.(Given pKA of acetic acid is 4.76)
Tuesday, June 16, 2015 by woo

analytical chemistry
a 0.4617g sample containing sodium bicarbonate was dissolved and titrated with standard 0.106M of hydrochloric acid solution , requiring 40.72ml. the reaction is: HCO3- + H+ -> H2O + CO2 Calculate the percent sodium bicarbonate in the sample. (Given molecular weight of ...
Tuesday, June 16, 2015 by zzz

Organic Chemistry
Which isomer of 1-ethyl-3-methylcyclohexane is more stable, cis or trans? My teacher hasn't covered this material as of yet, but we have a test done tomorrow on it. What is a cis and trans? Not sure how to begin figuring this out. My text book isn't helpful. Thanks
Monday, June 15, 2015 by Michelle

Chemistry
Balance TeO3^3- + N2O4 --> Te +NO3^- using oxidation numbers
Monday, June 15, 2015 by Sara

chemistry
1. Unless otherwise instructed, you may use the periodic table in the Chemistry: Problems and Solutions book for this test. You also may use the formulas on pages 238 243. A student increases the temperature of a 556 cm3 balloon from 278 K to 308 K. Assuming constant pressure...
Monday, June 15, 2015 by tony

chemistry
If 32.9mL of 0.170M BaCl2 are needed to react completely with 35.0mL of 0.160M Na2SO4 . How many grams of BaSO4 will be formed?
Monday, June 15, 2015 by jennifer

chemistry
If the theoretical yield of a reaction is 0.173g and the actual yield is 0.165g , what is the percent yield?
Monday, June 15, 2015 by dj

chemistry
How can i Fill in the missing words Ionisation energy, water, melting point, electronegativity, non-polar, solvent, pair, boiling points, polar A covalent bond is formed when a 1________ of electrons is shared between the bonding atoms.when the electrons are shared equally,a ...
Monday, June 15, 2015 by dennis

chemistry
At room temperature , the density of water is 1 g/ml and the density of ethanol is 0.789 g/ml . What volume of ethanol contains the same no. of molecules as are present in 175 ml of water?
Monday, June 15, 2015 by Kajal

chemistry
write a balanced chemical equation for the process of photosynthesis and the conditions of the reaction giving physical state of all the substances
Monday, June 15, 2015 by aakriti

science chemistry
A basic amino acid,arginine,has a molar mass of 174g.mol^-1.it has the following percentage composition:41,38% carbon, 18,39% of oxygen,32,18% of nitrogen and 8,O5% of Hydrogen.determine the molecular formular of arginine
Sunday, June 14, 2015 by bob

science chemistry
A given mass of helium(gas)occupies a volume of 3,6m^3 at a pressure of 105 kPa.if the temperature remains constant,calculate volume of the gas if the pressure is decreased to 70 kPa.
Sunday, June 14, 2015 by melissa

physical science chemistry
Fill in the missing words Ionisation energy, water, melting point, electronegativity, non-polar, solvent, pair, boiling points, polar A covalent bond is formed when a 1________ of electrons is shared between the bonding atoms.when the electrons are shared equally,a 2_______ ...
Sunday, June 14, 2015 by kem

Chemistry
Magnesium metal reacts with hydrochlroic acid according to following reaction: Mg(s) + 2HCl(aq) -> MgCl2(aq) + H2 (g) over interval of 10.00s, the mass of Mg changes by -0.22g. What is the corresponding rate of consumption of HCl (in Mol/s) ? So what i think i should do is ...
Sunday, June 14, 2015 by Rez

chemistry
Aspirin is a monoprotic acid called acetylsalicylic acid. Its formula is HC9H7O4. A certain pain reliever was analyzed for aspirin by dissolving 0.311 g of it in water and titrating it with 0.0398 M KOH solution. The titration required 22.32 mL of base. What is the percentage ...
Sunday, June 14, 2015 by walter

chemistry
how much faster does krypton diffuse than bromine under the same conditions of temperature and pressure?
Sunday, June 14, 2015 by nyakno

chemistry
"Stomach acid" is hydrochloric acid. A sample of gastric juice having a volume of 6.68 mL required 13.90 mL of 0.0161 M KOH solution for neutralization in a titration. What was the molar concentration of HCl in this fluid? C(HCl) = If we assume a density of 1.00 g mL...
Sunday, June 14, 2015 by walter

chemistry
A student prepares a solution of hydrochloric acid that is approximately 0.1 M and wanted to determine its precise concentration. A 25.00 mL portion of the HCl solution is transferred to a flask, and after a few drops of indicator are added, the HCl solution is titrated with 0...
Sunday, June 14, 2015 by walter

chemistry
A 12.6 mL sample of vinegar, containing acetic acid, was titrated using 0.542 M NaOH solution. The titration required 24.1 mL of the base. what is the molar concentration of acid in the vinegar?'
Sunday, June 14, 2015 by walter

chemistry
how many grams of methanol must be added to 5.00kg of water to lower its freezing point to -12.0 degrees C? for each mole of solute the freezing point of 1kg of water is lowered 1.86 degrees C?
Sunday, June 14, 2015 by jennifer

chemistry
what is the freezing point of a solution that contains 20.2g of urea CO(NH2)2 in 295mL water? Assume a density of water of 1.00g/mL
Sunday, June 14, 2015 by jennifer

chemistry
148 mL of 0.325 M MgCl2 is mixed with 68.7 mL of 0.388 M NaOH and allowed to react completely. how many grams of Mg(OH)2 will form?
Sunday, June 14, 2015 by walter

Organic Chemistry
What is the hybridization of all the atoms (other than hydrogen) in each of the following species? a) NH3 e) +NH4 i) H3O+ b) BH3 f) +CH3 j)H2C=O c) -CH3 g) HCN d)*CH3 h) C(CH3)4 There are a couple I don't know how to do. Please help? Did I do the other correctly? Thanks. a...
Sunday, June 14, 2015 by Michelle

chemistry
'24.6 mL of 0.488 M NaCl is added to 24.6 mL of 0.312 M AgNO3. How many moles of AgCl would precipitate? What would be the concentrations of each of the ions in the reaction mixture after the reaction? Ion Concentration (M) Ag+ M NO3- M Na+ M Cl- M'
Saturday, June 13, 2015 by walter

Chemistry
What intermolecular forces are present in CSH2??
Saturday, June 13, 2015 by Jacob

chemistry
What volume of water should be added to 50 ml of HNO3 having specific gravity 1.5g ml-1 and 63.0%by weight to have one molar solution
Saturday, June 13, 2015 by adarsh

chemistry
ow many grams of NH3 can be produced from 2.89mol of N2 and excess H2. Express your answer numerically in grams.
Friday, June 12, 2015 by caro

chemistry
How many grams of NH3 can be produced from 2.89mol of N2 and excess H2. Express your answer numerically in grams.
Friday, June 12, 2015 by caro

chemistry
if you had excess chlorine, how many moles of of aluminum chloride could be produced from 17.0g of aluminum? Express your answer numerically in moles.
Friday, June 12, 2015 by caro

chemistry
23.8 ml of a 2.0 mol/l surfuric acid solution reacted completely with 68.0 ml of potassium hydroxide. find the concentration of potassium hydroxide
Friday, June 12, 2015 by walter

chemistry
23.8 ml of a 2.0 mol/l surfuric acid solution reacted completely with 68.0 ml of potassium hydroxide. find the concentration of potassium hydroxide
Friday, June 12, 2015 by walter

Chemistry
Can someone help me with these two questions? Thank you! a.) Describe (give instructions) how you would prepare 7.00 L of 0.750 M K2CrO4 from a 2.25 M K2Cro4 stock solution b.) A stock solution containing Ba2+ ions was prepared by dissolving 23.0 grams of pure barium metal in ...
Thursday, June 11, 2015 by Anonymous

Chemistry
A solution is prepared by dissolving 35g hoemoglobin in water to make 1 litter. If osmotic pressure of solution is 10.00mmHg at 25 degree centigrade. Calculate the molarmass of the hoem6globin
Thursday, June 11, 2015 by Shuhudaht

analytical chemistry
draw the complexation titration of 50ml of 0.1M MgCl2 with 0.2M EDTA(take aminimum of six point) kf=4.9*10^8?
Thursday, June 11, 2015 by baynes

chemistry
Calculate the number of moles volume number of molecules of carbon dioxide liberated when 200 grams of limestone decomposed .
Thursday, June 11, 2015 by Anonymous

chemistry
Calculate the number of moles volume number of molecules of carbon dioxide liberated when 200 grams of limestone decomposed .
Thursday, June 11, 2015 by Anonymous

Organic Chemistry
Is eutectic point and eutectic mixture the same thing? If not what is the difference between the two? Thanks in advance.
Thursday, June 11, 2015 by Michelle

Chemistry
Aqueous calcium bromide was mixed with aqueous gold(I) perchlorate, and a crystallized gold(I) bromide product was formed. Consider the other product and its phase, and then write the balanced molecular equation for this precipitation reaction.
Thursday, June 11, 2015 by Alicia Estrada

Chemistry
What is the total internal energy change (∆E), in J, of a system that releases 202.90 J of heat and absorbs 315.7 J of work from the surroundings?
Wednesday, June 10, 2015 by Katie

chemistry
Calculate the number of moles of each of the ions in the following solution: 30.8 mL of 0.507 M AlCl3
Wednesday, June 10, 2015 by walter

chemistry
How many milliliters of water must be added to 153.2 mL of 2.73 M KOH to give a 1.68 M solution?
Wednesday, June 10, 2015 by walter

chemistry
A coin dealer offers to sell you an ancient nickel coin that is 3.1 cm in diameter and 4.65 mm in thickness. A) The density of nickel is 8.9 g/cm3. How much should the coin weigh if it is pure nickel? (in grams) B) If nickel sells for $0.216 per troy ounce, how much is the ...
Wednesday, June 10, 2015 by Abe

Chemistry
How much heat would be absorbed by 55 grams of copper when heated from 24 degrees Celsius to 40 degrees Celsius? The specific heat of copper is .385 My answer is 338.8 Joules. Is this correct?
Wednesday, June 10, 2015 by H

chemistry
Okay so the question is: what would be the molarity of a saturated aqueous solution of NaI prepared at 25 C, assuming that the added NaI does not add significantly to the volume of the water? My question is, I got confused on what formula I use to for the question, because the...
Wednesday, June 10, 2015 by Unknown

chemistry
how do you do acids/bases, oxidation, buffers, and Boyle's Law. what are the rules for each, can u give me an example for each and explaining how you get the answers, because i'm confused on how you do these.
Wednesday, June 10, 2015 by reina bonilla

chemistry
What volume of hydrogen gas at standard temperature and pressure can be collected from the electrolysis of water using a current of 100mA for a period of 3 hours? I know that the answer is 0.125 L but I don't know how to approach the problem. I multiplied 100*10^-3 by 3600...
Wednesday, June 10, 2015 by Anon

Chemistry
Find the number of atoms in 138 grams of nickel. I'm not sure where to start. Can anyone help me?
Wednesday, June 10, 2015 by A

Chemistry
A piece of copper 12 cm long, 8.5 cm wide, and .50 cm thick has a mass of 457 grams. What is its density? D = m/v D = 457 g / 12x8.5x.50 D = 457 / 51 = 8.96 g/cm^3 Is this correct?
Wednesday, June 10, 2015 by T

chemistry
How much 35.6 M H2SO4 is needed to make a 1 L solution that is .007 ppm? Not sure how to convert from M to ppm-is there a formula?
Wednesday, June 10, 2015 by Nat

Chemistry
If a 0.688 mole sample of silver at 19.6°C absorbs 1.162 kJ of heat, what is the final temperature in C?
Wednesday, June 10, 2015 by Josh

Chemistry
Could a buffer system employing H3PO4 as the weak acid and H2PO4^- as the weak base be used as a buffer system within cells? Explain. I know the answer is no but I'm not really quite sure how to explain why.
Tuesday, June 9, 2015 by Candice

Chemistry
How much time a 250 watt heater takes to heat up 1 kg of water from 20 degree c to 50 degree c?
Tuesday, June 9, 2015 by Maya

Chemistry
A beaker contains 50 gm water at 20 degree c.How much water having temperature 60 degree C should be added to have an equilibrium temperature of 40 degree c?
Tuesday, June 9, 2015 by Maya

Kainantu sec..science(chemistry)
How many moles of O2 are there in the above sample at the initial temperature and pressure?
Tuesday, June 9, 2015 by Tema Andrew

Kainantu sec..science(chemistry)
A sample of O2 gas occupies 1.93L at a pressure of 10.0atm at 100 degree celsius. What volume will the sample occupy at stp?
Tuesday, June 9, 2015 by Tema Andrew

Kainantu sec..science(chemistry)
At stp what volume of SO2 gas will be produced when 2.00g of CS2 is burned
Tuesday, June 9, 2015 by Tema Andrew

Chemistry
1.3188g of antacid is weighed and mixed with 75.00mL of excess 0.1746M HCl. The excess acid required 27.20mL of 0.09767M of NaOH for back titration. Calculate the amount of CaCO3 in the tablet.
Monday, June 8, 2015 by B

Chemistry
analyze and describe the different types of genetic mutations and their effects
Monday, June 8, 2015 by Michelle

Chemistry
How much heat is absorbed/released when 20.00 g of NH2 reacts in the presence of excess O2 to produce NO and H2O according to the following chemical equation: 4NH3 + 5O2 --> 4NO + 6H2O, deltaH= +1168 kJ. The answer is 342.9 kJ of heat absorbed. I want to know how to ...
Monday, June 8, 2015 by Jenny

Chemistry
A tanker spilled 5,000l ammonia (approximately 0.2M). How much sulphuric acid is needed to nuetralize ammonia?
Monday, June 8, 2015 by Anne

Chemistry
Can someone please help me with this question? Hydrazine is somewhat toxic. Use the half-reactions shown be- low to explain why household bleach (a highly alkaline solution of sodium hypochlorite) should not be mixed with household ammonia or glass cleansers that contain ...
Sunday, June 7, 2015 by Anonymous

chemistry
Chemical reaction between solid ammonium chloride and solid barium hydroxide octahydrate 2NH4Cl(s)+Ba(OH)*8H2O(s)->2NH3(aq)+Ba​Cl2(aq)+10H2O(l) the change in heat for this reaction is 54.8kJ how much energy would be absorbed if 24.9g of NH4Cl reacts
Sunday, June 7, 2015 by jennifer

chemistry
for N2O4(g)-><-2NO2(g) the value of K at 25 degrees C is 7.19*10-3. calculate N2O4 at equilibrium when NO2 =2.80*10-2 mol/L. Calculate NO2 at equilibrium when N2O4=7.00*10-2 mol/L
Sunday, June 7, 2015 by jennifer

chemistry
4HCl(g)+O2(g)-><-2Cl2(g)+2H2O(g) with Hcl=0.80M, Cl2=3.0M, O2=0.20M H2O=3.0M what is the equilibrium constant
Sunday, June 7, 2015 by jennifer

chemistry
I2(g)+Cl2(g)-><-2ICl(g) molar concentrations are I2=1.5M, Cl2=0.60M and ICl=5.0M calculate the ratio of products to reactants assume that the reaction has not yet regained equilibrium
Sunday, June 7, 2015 by jennifer

chemistry
Fe3O4 can be reduced by treatment with hydrogen to yield iron metal and water vapor write the balanced equation. this process required 36kcal for every 1.00 mol of Fe3O4 reduced. how much energy in kcal is required to produce 64g of iron. how many grams of hydrogen are needed ...
Sunday, June 7, 2015 by jennifer

chemistry
methanol CH3OH is used as race car fuel write the balanced equation for the combustion of methanol. change in heat= -174kcal/mol methanol for the process How man kilocal are released u burning 33.0g of methanol
Sunday, June 7, 2015 by jennifer

chemistry
How much heat in kilocalories is absorbed in the reaction of 1.94g of Na with H2O? 2Na(s)+2H2O(l)->2NaOH(aq)+H2(g) change in heat= -88.0kcal/mol
Sunday, June 7, 2015 by jennifer

chemistry
During the combustion of 5.00g of octane C8H18, 239.5 kcal is released. Write a balanced equation for the combustion reaction. Are reactants or products favored? What is the sign of change of heat for this reaction? how much energy is released by the combustion of 1.53mol of ...
Sunday, June 7, 2015 by jennifer

Chemistry
Methanol is produced commercially by the catalysed reaction of carbon monoxide and hydrogen: CO(g) + 2H2(g)  CH3OH(g). An equilibrium mixture in a 2.00 L vessel is found to contain 0.0406 mol CH3OH, 0.170 mol CO, and 0.302 mol H2 at 500 K. Calculate Kp at this ...
Sunday, June 7, 2015 by Ng Chew Hong

Chemistry
What are some of the distinctive properties of gases with respect to: density, volume, shape?
Sunday, June 7, 2015 by Mark

Chemistry
Calculate the volume of solution of 3.6 M NH4CI needed to prepare 350.0ml of 1.24 M NH4CI. How many grams of ammonium chloride are in the solution you created in the above problem.
Sunday, June 7, 2015 by Donna

Chemistry
How many moles of potassium sulfate would you need to prepare 1200 grams of 5.0% sulfate (m/m) solution? Calculate the volume of solution of 3.6 NH4CI needed to prepare 350.0ml of 1.24 M NH4CI. How many grams of ammonium chloride are in the solution you created in the above ...
Sunday, June 7, 2015 by Donna

Chemistry
A chemist wants to make 150 mL of a 1.26 M solution of carbonic acid to be used in the lab. How many grams of H2CO3 does the chemist need to make this solution? I converted mL to .150L, multiplied .150*1.26= =0.189 to get mol. H2CO3=62.028 so I multiplied this by 0.189 to get ...
Saturday, June 6, 2015 by Nick

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