Chemistry

Chemistry (Urgent)
Ksp of PbI2 at 25 degrees celcius and 15 degrees celcius is 7.5×10^-8 and 7.5×10^-9 respectively. (Pb=207 I=127) 1) write an expression for the equilibrium of PbI2 2)write an equation for the Ksp of PbI2 3)calculate the solubility of PbI2 at 25 degrees celcius in gdm^-3 4)...

Chemistry
My school notes say : pH < pOH is acidic pH > pOH is basic Is this correct, I was thinking that if the pH is less than pOH than it was a basic solution

Chemistry
Calculate the wavelength of nitrogen molecule travelling with a speed of 500 m/s

Chemistry
If a chemical reaction uses 140 g of N2. How many moles is this? n=m/M

Chemistry
Suppose a student diluted and titrated a bleach unknown exactly as described in the experimental procedure, except only a single titration was performed which required 16.22 mL of 0.100 M Na2S2O3. Calculate the number of moles of Na2S2O3 used in the titration.

CHEMISTRY: HESS'S LAW need help!
I'm just overly confused on how to begin this especially with the fractions... please show step by step if you could. Quiz very Soon! Example A: H2(g)+1/2 O2 (g) ----> H2O(l) ... ΔH= -285.8 kJ N2O5(g) + H2O(l) -----> 2HNO3(l) ΔH= -76.56 kJ 1/2 N2(g) + 3/2 O2(g) +1/2 H2...

chemistry
what is the net ionic equation for AlBr3(aq) + 3LiOH(aq)

Chemistry
Use the concentrations and volumes of hydrogen peroxide and KI before mixing (Table 1), calculate the post-mixing concentrations. Before mixing: [H2O2] = 0.88M [KI] = 0.500M Table 1: before mixing 1. Vol H2O2 = 4.0 mL, [H2O2] = 0.88M 2. Vol KI = 1.0 mL, [KI] = 0.500 M units: M...

chemistry
THE QUESTION ASKS TO CALCULATE THE AMOUNT (IN GRAMS) OF CARBON DIOXIDE FROM THE AMOUNT OF SODIUM BICARBONATE THAT YOU USED IN THE REACTION Run 1. The reaction of citric acid and sodium bicarbonate is written as H3C6H5O7(aq) + 3 NaHCO3(aq) → Na3C6H5O7(aq) + 3 H2O(l) + 3 CO2(g...

Chemistry
Tooth enamel consist mainly of hydroxyapatite (Ca5(PO4)3(OH). When tine (II) Flouride is added to toothpaste it reacts with the enamel to product a more decay-resistant material fluorapatite (Ca(PO4)3F. The by-products of this reaction are tin (II) oxide and water. What mass ...

Analytical Chemistry
A solution is prepared by dissolving 0.2222 (¡¾0.0002) g of KIO3 in 50.00 (¡¾0.05) mL. (i) Calculate the molar mass of KIO3 with its associated uncertainty to the correct number of significant figures. (ii) Find the molarity and its uncertainty with an appropriate number ...

chemistry
Write the reactants and products of the reaction between zinc and oxygen. Include the half-reactions. What type of reaction is this? I know the reaction is 2Zn + O2 -> 2ZnO I am not really sure where to go from here.

Chemistry
Calculate the mass of solid AgNo3 that can be added to 2.0 L of 0.10M K2CrO4 solution in order to just start precipitation? Here is what I have done so far: 2AgNO3(aq) + K2CrO4(aq) ==> Ag2CrO4(s) + 2KNO3(aq) Ag2CrO4(s) ===> 2Ag^+ CrO4^^2- Ksp = [Ag^+]^2[CrO4^2-] Ksp = (...

chemistry
A student dissolves a .726 g aspirin tablet in water and titrates the solution with .272 M NaOH are required to reach the equivalence point. Calculate the percentage of acetylsaliclic acid in the tablet. I am not really sure where to start with this. I unfamiliar with problems...

Chemistry
Calculate ΔG at 25°C for the precipitation of lead(II) iodide from mixing 100. mL of 0.10 M lead(II) nitrate solution with 100. mL of 0.10 M sodium iodide solution. The ΔG° for this precipitation reaction at 25°C = −46.2 kJ/mol.

Chemistry
Thanks to Dr. Bob for answering all these questions! I always do poorly on conceptual problems. Consider the following equilibrium system at 25°C and select the true statement below: H2PO4−(aq) + SO42−(aq) ↔ HSO4−(aq) + HPO42−(aq) ΔG°rxn > 0 at 25°C (1) this ...

Chemistry
Silicon Carbide, SiC, is prepared by heating silicon dioxide in the presence of graphite. Carbon dioxide is the by-product of the reaction. How many grams of silicon carbide can be formed from the reaction of 50.0 grams fo graphite with 50.0 grams of silicon dioxide?

Chemistry
Classify the reaction type (formation, simple composition, decomposition, combustion, single replacement, double replacement) and predict the balance equation 1. AL(s) + 02(g) ------> 2. Ag2O(s)------> 3. Br2(1) + KI(aq) ------->

Chemistry
Give an example of each of the following reactions, showing balanced equations for reactants= products and show s, I, g, or aq A.) synthesis B.) decomposition C.) single replacement D.) double replacement E.) neutralization F.) combustion

Chemistry
A scientist studying the reaction between decaborane (B10H18) and oxygen mixed 1.00 x 10^2 grams of decaborane with 2.75 x 10^2 grams of oxygen. Compute the masses of all substance present after the reaction went ot completion, generating B2O2 and water as the only products.

Chemistry
Calculate the mass of solid AgNo3 that can be added to 2.0 L of 0.10M K2CrO4 solution in order to just start precipitation?

chemistry
The alcoholic fermentation of350 g/l glucose syrup ceases when the alcoholic degree of the mixture attains 16º (16ml ethanol in 100ml of the solution) Write the reaction of the fermentation reaction. Consider the fermentation of 100L of the glucose syrup. Determine the volume...

Chemistry
What is the approximate ratio of the solubility of CaSO4 (Ksp = 2.4 x 10−5) in pure water to the solubility of CaSO4 in 0.10 M Na2SO4 at the same temperature?

Chemistry 2
A scientist studying the reaction between decaborane (B10H18) and oxygen mixed 1.00 x 10^2 grams fo oxygen. Compute the masses of all substances present after the reaction went to completion, generating B2O3 and water as the only products.

chemistry
Help me conclude my lab experiment on formula of a hydrate.with the aim of determine the number of molecules of water associated with a hydrated inorganic salt

Chemistry
At 3745°C, K = 0.093 for the following reaction. N2(g) + O2(g) equilibrium reaction arrow 2 NO(g) Calculate the concentrations of all species at equilibrium for each of the following cases. (a) 2.0 g N2 and 3.0 g O2 are mixed in a 1.3-L flask. [N2] [O2] [NO] (b) 1.5 mol pure...

Chemistry
An organic compound on analysis gave C=57.8% and H=3.6% and rest of oxygen.The vapour density of the compound was found to be 83.Find the molecular formula of the compound?

Chemistry
A sample of a substance (containing only C, H, and N) is burned in oxygen. 7.961 g of CO2, 1.164 g of H2O and 1.551 g of NO are the sole products of combustion. What is the empirical formula of the compound?

Chemistry
Calculate how many moles of Na2S2O3 must be added to dissolve 0.020 mol AgBr in 1.0 L of water at 25°C (assume constant volume). AgBr(s) ↔ Ag+(aq) + Br−(aq) Ksp = 3.3 x 10^−13 Ag+(aq) + 2S2O32−(aq) ↔ [Ag(S2O3)2]3−(aq) Kf = 2.0 x 10^13 (1) 0.0078 mol (2) 0.048 mol...

Chemistry
How many hydrogen atoms are present in 6.49 moles of hydrogen molecules

Chemistry
When mixing 10m/L of 6 M HCl (diluted with 10 mL of water) with 0.1 g of Mg, how many moles of H2 are created and how many moles of Mg are reactant? I understand I must use n=(PV)/(RT) to find H2, since it is a gas, but the constant R is still confusing to me and I cannot ...

Chemistry
A forensic scientist is given a white substance that is thought to be cocaine. The substance is found to have a percent composition: 49.48% C, 5.19% H, 28.85% N, and 16.48% O. What is the empirical formula for this substance? Is it cocaine?

chemistry
describe briefly a suitable laboratory procedure for separating a mixture of NaCl4,NH4Cl and PbCl2

chemistry
Under the same condition of temp.and pressure hydrogen gas diffuses 8 times as fast as gas y.calculate the relative molecular mass of gas y.(R.M M_2

chemistry
A certain amount of gas occupy 5.0dm cube at 2atm.and 10 degree centigrade .calculate d number of mole present(R_0.082atm)

chemistry
Under the same temp.and pressure ,nitrogen gas diffuses 8 times as fast as gas y .calculate the relative molecular mass of gas y.

CHEMISTRY
Determine the concentrations of Na2CO3, Na , and CO32– in a solution prepared by dissolving 2.22 × 10–4 g Na2CO3 in 2.25 L of water. Express all three concentrations in molarity. Additionally, express the concentrations of the ionic species in parts per million (ppm). ...

chemistry
How much energy is evolved during the formation of 98.7 g of Fe, according to the reaction below? Fe2O3(s) + 2 Al(s) → Al2O3(s) + 2 Fe(s) ΔH°rxn = -852 kJ A. 482 kJ B. 753 kJ C. 1.51 × 10ee3 kJ D. 4.20 × 10ee3 kJ

Chemistry
Calculate the molarity of the H2SO4 solution if 17.45 mL of NaOH was necessary to reach the endpoint of titration. The molarity of the NaOH solution was 0.425 M and 26.30 mL of H2SO4 was added to the Erlenmeyer flask. H2SO4(aq) + 2 NaOH (aq) -----> Na2SO4 (aq) + 2 H2O (l) I...

chemistry
hw much 0.1N NaoH would u have added to 30ml of 0.1N Hcl at a equivalent point?

Chemistry
Hydrogen iodide decomposition via a second-order process to produce hydrogen and iodine according to the following chemical equation: 2 HI(g) -> H2 (g) + I2 (g) If it takes 489 seconds for the initial concentration of HI to decrease from 0.0693 M to 0.0174 M, what is the ...

Chemistry
sulfuric acid can be prepared by a multistep process summarized as: 2 SO2 + O2 + 2 H2O--> 2 H2SO4 What mass of sulfuric acid could be produced daily by a process using 38 kg per day of sulfuric dioxide with a 70% conversion efficiency ("yield"), assuming that sulfuric ...

Chemistry
How many grams of a solid mixture containing strontium chloride would one need to make 558 mL of a 0.100 M strontium chloride solution, if the solid mixture contains 58.6% strontium chloride by weight

Chemistry
High-pressure sodium vapor lamps are used in street lighting. The two brightest lines in the sodium spectrum are at 589.00 and 589.59 nm. What is the diffrence in energy per photon of the radiations corresponding to these two lines?

Chemistry
Calculate the energy needed to ionize an electron of H atoms from its second excited state.

Chemistry
A hydrogen atom in one of its excited states ha an energy of -1.5129^20 J. What is the frequency of radiation is emitted when the atom relaxes down to its ground state?

Chemistry
Consider a 1.0 L container of Neon gas at STP. Will the average kinetic energy, average velocity,and frequency of the collisions of gas molecules with the walls of the container increase, decrease, or remain the same under each of the following conditions? a. The temperature ...

Chemistry
A compressed gas in a cylinder contains 1000.0 g of argon gas. The pressure inside the cylinder is 2050 psi at 18 degrees Celcius. How much gas remains if the pressure is decreased to 650. psi at a temperature of 26 degrees Celcius?

chemistry, science
how many moles of he atoms are there in 0.02g of he?

chemistry
A 75.0g sample of liquid contains 17.5% by mass of H3PO4 (molar mass = 98.0g/mol). If 215.0mL of Ba(OH)2 is needed to completely neutralize the acid, determine the concentration of the Ba(OH)2 solution used

Chemistry
Determine the concentration for the following solutions 2.0g KOH is dissolved in water to make 200.0 ml of solution

Chemistry
How much energy (in kj) is required to ionize 2.78 moles of hydrogen atoms the right answer is: 3.65x10^3 kj wondering how they got this answer.

Chemistry
Calculate the ionization energy (in kj) for a mole of hydrogen atoms, making the assumption that ionization is the transition from n=1 the correct answer is : 1.31x10^3 kJ

Chemistry
When 25g of ice lose 2092 J of heat at 0 degrees Celsius, what will be the new temperature of the ice? Calorimetry problem

chemistry
already missed question so I just need help figuring out what I did. Small amounts of chlorine gas can be gener- ated in the laboratory from the reaction of manganese(IV) oxide with hydrochloric acid: 4 HCl(aq) + MnO 2 (s) → 2 H 2 O( ℓ ) + MnCl 2 (s) + Cl 2 (g). What mass ...

Chemistry
what is the minimum uncertainty in the position of an electron moving at a speed of 4 x 10^6 m/s ± 1 %? I keep getting 1.44 x10^-11 m, but the right answer is 1x10^-9 m.

chemistry
how can i determine via infrared spectrum whether the alcohol that was oxidized was primary or secondary? i did a lab experiment in which we oxidized a diol with bleach and i need to figure out which -OH group was oxidized into a C=O. What are the signs of whether the -OH is ...

Chemistry
4.72 g of a compound of carbon, hydrogen, and silver was burned in an atmosphere of oxygen, yielding 7.95 g of CO2, 1.02 g of H2O and 3.02 g of a mixture of silver and silver oxide. Because the production of this mixture yielded an indeterminate value for the amount of silver...

Chemistry
Can geranium be used to detect infrared radiation emitted by a remote control device that has a wavelength of 902 nm? the work function (binding energy) of geranium is 7.61 x10^-19 J?

chemistry help, urgent!
Which of the following should you add to stabilize the pH of a solution? solute acid <<my choice buffer base

Chemistry
the lead (II) nitrate in 25.49 ml of a 0.1338M solution reacts with all of the aluminum sulfate in 25.00 ml solution. What is the molar concentration of the aluminum sulfate in the original aluminum sulfate solution? For a question like this how do I find out it is a 3:1 ratio...

Chemistry Help
The most effective buffer solutions have equal concentrations of salt and acid (or base). Find the pH of a buffer solution with equimolar concentrations of: (a) HCOOH and NaCOOH (Ka = 3.5 x 10-4 for HCOOH) (b)CH3NH2 and CH3NH3Cl (Kb = 3.7 x 10-4 for CH3NH2) Thank you!

Chemistry
Calculate the molar mass of a molecular compound if a solution of 6.70 g of the compound in 22.60 g of water boils at 100.78 degrees C (at 760mmHg).

Chemistry
A is a solution of hydrochloric acid containing 3.650g of HCl in 1dm3 of solution. B is a solution of impure sodium carbonate. 25cm3 of B require 22.7cm3 of A for complete reaction. Given that 5.00g of impure B was dissolved in1dm3 solution,what is the percentage by mass pf ...

Chemistry
How much ethylalcohol must be added to 1litre of water so that the solution will freeze at 14 farenite, kf of wa ter is 1.86 c/mol

Chemistry
the lead (II) nitrate in 25.49 ml of a 0.1338M solution reacts with all of the aluminum sulfate in 25.00 ml solution. What is the molar concentration of the aluminum sulfate in the original aluminum sulfate solution?

chemistry
calculate the volume of hydrogen that will combine with 40 litres of oxygen to form steam at 150°C and atmospheric pressure?

Chemistry
Compound A consisting of carbon and hydrogen only. The compound was found to contain 80% carbon by mass,cal. its empiri.

Chemistry
Find the ratio of the volumes of NaC3H5O3 soloution to HC3H5O3 (lactic acid) required to prepare a buffer with a pH of 3.90. the solutions are equal in molarity. Ka = 1.4 x 10-4 for HC3H5O3. ratio = ________ mL of NaC3H5O3 per mL of HC3H5O3

Chemistry
Find the pH of a buffer solution with equimolar concentrations of: HCOOH and NaCOOH (Ka = 3.5 x 10-4 for HCOOH)a

Chemistry
A 5.00g of sodium chloride is Dissolved m, exactly 250 mL calibrated volumetric flask, what is the molarity of the solution?

CHEMISTRY
Mg(s) + FeCl2(aq) → MgCl2(aq) + Fe(s). IS THE IRON(II) ION OXIDIZED?

CHEMISTRY
2 C8H18 + 25 O2 → 16 CO2 + 18 H2O. WHAT IS THE MOLE-TO-MOLE RATIO BETWEEN OXYGEN GAS AND WATER?

chemistry
Four gases were combined in a gas cylinder with these partial pressures: 3.5 atm N2, 2.8 atm O2, 0.25 atm Ar, and 0.15 atm He.What is the mole fraction of N2 in the mixture?

Chemistry
What mass of solute is needed to make the following solutions: 0.238 M FeCl3 solution in 1000. mL of solution.

Chemistry
calculate the change in ph for 1l of buffer solution containing NH4OH and NH4Cl upon addition of 1) 0.02 moles of HCl 2) 0.02 moles of NaOH I got the initial pH as 9.2504 But now Im stuck cus I dunno what happens when we add HCl and NaOH? Please help! :)

chemistry
If 14.50mL of 0.25M sodium hydroxide reacts completely with 25.0 mL of hydrochloric acid, what is the concentration of the hydrochloric acid?

Chemistry
A 0.2638 g impure sodium carbonate sample is analyzied by titrating the sodium carbonate with the 0.1288 M hydrochloride solution requiring 38.27 mL. The reaction is CO3^2- + 2H^+ --> H2O + CO2 Calculate the percent sodium carbonate in the sample.

chemistry
calculate the volume of 4.0 M hydrochloric acid needed to make 100.0 mL of 0.10 M hydrochloric acid.

chemistry
how many moles of water vapour are formed when 10 liters of butane gas C4H10 is burned in oxygen at stp?

Chemistry
Describe how to prepare 10 mL of 0.200 acetate buffer, pH 5.00, starting with pure acetic acid and solutions containg 3 M HCl and 3 M NaOH. Include both quantitate and qualitative details. I know that a strong base reacts completely witha weak acid because the equilibrium ...

Chemistry
Write the formula of the corresponding acid that contains this anion. Express your answer as a chemical formula. The arsenite ion has the formula AsO33−.

chemistry
how many grams of CO2 could be produced from 100.0 grams of CH4? CH4 + 2O2 -> CO2 + 2H2O

chemistry
Confused on how to find the reactants in these two compounds Ba(OH)2 (aq) + I2Zn (aq) -> ?? Additionally, I am not really sure how to find the ionic equation for this.

Chemistry
A 75.0g sample of liquid contains 17.5% by mass of H3PO4 (molar mass = 98.0g/mol). If 215.0mL of Ba(OH)2 is needed to completely neutralize the acid, determine the concentration of the Ba(OH)2 solution used. WITH FULL EXPLANATION PLEASE!

Chemistry
A piece of metal ribbon has a mass of 6g.It has a density of 4g/mL. What is the volume of the ribbon?

chemistry
An environmental chemist needs to determine the amount of Fe+2 ions in a simple of polluted water from a rusting industrial plant. one procedure is to analyses the sample by using solution of sodium dochromate, Na2Cr2O7. identify the oxdising agent and the reducing agent in ...

chemistry
what volume of chlorine is required to produce 25.4grams of copper II chloride at 18 degrees celsius and 2.13 atm

Chemistry
Using the following data, determine the initial rate by calculating the slope of the tangent line at time zero. Time (s). [I2] (mM) 0. 0 20. 0.009 40. 0.017 60. 0.023 80. 0.029 100. 0.034 120. 0.039 140. 0.043 160. 0.046 180. 0.049 I can't figure out how to make a tangent ...

Chemistry
Can someone clarify where I'm going wrong with this? Kw for pure water is 1.2 x 10-15 at 5°C. The pH of pure water at 5°C? I thought Kw=[H3O][OH]... I've tried a few different things, but none seem to work. Thanks!

Chemistry
N2(g) + 3 H2(g) → 2 NH3(g) [balanced] If 5.42 g of nitrogen gas are reacted with 5.42 g of hydrogen gas, which of the reactants is the limiting reactant? Use the molar mass data below if necessary. Molar mass of N2 = 28.02 g/mol Molar mass of H2 = 2.02 g/mol Molar mass of ...

chemistry
N2(g) + 3 H2(g) → 2 NH3(g) [balanced] If 5.42 g of nitrogen gas are reacted with 5.42 g of hydrogen gas, which of the reactants is the limiting reactant? Use the molar mass data below if necessary. Molar mass of N2 = 28.02 g/mol Molar mass of H2 = 2.02 g/mol Molar mass of ...

Chemistry
A sample of 10.7 g of O2 reacts completely with CO to form CO2. 2 CO + O2 → 2 CO2. How many grams of CO is required.

Chemistry
If 32.3 grams of KCl are dissolved in 192 grams of water, what is the concentration of the solution in percent by mass? 5.94% KCl 8.55% KCl 14.4% KCl 16.8% KCl Can someone explain this to me? I don't want the answer I just want to know how to find it.

Chemistry
How many grams of K2SO3 would be required to react completely with 200.0 mL of 0.245 M HCl

chemistry
. What would be the molarity of the solution produced when 276 mL of 6.00 M NaOH is combined with 125 mL of a 2.00 M NaOH solution?

Chemistry
You put a rock weighing 45g into a graduated cylinder. Before you put the rock in the graduated cylinder, the volume of water in the cylinder is 10mL. After you put the rock in the graduated cylinder, the volume rises to 25mL. What is the density of this 3rd rock?

Chemistry 101
Fe3+ and CN-

chemistry
Create balanced equation, given the two compounds in aqueous solution may react with one another. State whether or not a chemical reaction occurs. Make sure to include the state of each reactant and product. If a precipitation reaction occurs, provide the ionic and net ionic ...

Chemistry
Write the Kc expression for the following reaction: Fe3+ + SCN- = FeSCN2+