126 Answered Questions for the topic College Chemistry

How many moles of O2 are needed to oxidize 6.71 moles of CuFeS2 in the reaction 2 CuFeS2 + 5 O2 ———> 2 Cu + 2 FeO + 4 SO2

I really don't know how to do it I've tired and tried. I know how to balance, I have consistantly practiced but am getting no where. How many moles of O2 are needed to oxidize 6.71 moles of CuFeS2... more

How many moles of NaCl are needed if we want to make 4.37 moles of AgCl by the reaction 3Fe2O3 + 3O -> 2Fe3 + 3CO2

How many moles of NaCl are needed if we want to make 4.37 moles of AgCl by the reaction 3Fe2O3 + 3O -> 2Fe3 + 3CO2

If 0.528 mole of Al2S3 react with 3.70 mole HCl, how mant grams of H2S are formed

If 0.528 mole of Al2S3 react with 3.70 mole HCl, how mant grams of H2S are formed

Calculate the mass of KHP needed to react completely with 25 mL of a 0.10 M NaOH solution. Consider the reaction equation to be as shown below.

 NOTE: The “P” in KHP ( 204 g/mol ) is an abbreviation for “phthalate”. It is not the element phosphorus. Calculate the mass of KHP needed to react completely with 25 mL of a 0.10 M NaOH solution.... more

PLEASE HELP ME WITH CHEM TITRATION PROBLEM??!!!

A 25.0 mL sample of 0.150 M hypochlorous acid is titrated with a 0.150 M NaOH solution. What is the pH after 26.0 mL of base is added? The Ka of hypochlorous acid is 3.0 × 10-8.   7.51 11.47 7.54... more

Buffer/Titration Chemistry Problem??! PLEASE HELP - I AM LOST!!!

A 25.0 mL sample of 0.723 M HClO4 is titrated with a 0.273 M KOH solution. The H3O+ concentration after the addition of 66.2 mL of KOH is __________ M. 0.723 1.00 × 10-7 2.81 × 10-13 0.439... more

Equilibrium Constant

The basic question I am asking is how does varying the initial concentrations of reactant(s) in a chemical reaction affect the equilibrium constant. What I have so far is:   Using this basic... more

You carefully weigh out 17.00 g of CaCO3 powder and add it to 68.85 g of HCl solution. You notice bubbles as a reaction takes place. (contnd at description)

Question:You carefully weigh out 17.00 g of CaCO3 powder and add it to 68.85 g of HCl solution. You notice bubbles as a reaction takes place. You then weigh the resulting solution and find that it... more

n an actual combustion expirement 88 grams of propane produced 176 grams. how many grams of co2 should have been produced theoretically

in an actual combustion expirement 88 grams of propane produced 176 grams. how many grams of co2 should have been produced theoretically

Full question is in the description

the ratio of oxygen to nitrogen by mass in NO2 is 2.29. The ratio of chlorine to nitrogen by mass in NCl3 is 7.61. Find the ratio of oxygen to chlorine by mass in Cl2O.

How many grams of sucrose are needed to prepare 100 mL of 5% sucrose?

I know the molecular weight of sucrose is 342 g/mol

CHEMISTRY PLEASE HELP!!!!!!! Calculate the concentration of a crystal violet solution prepared by diluting 4.0 mL of 1.0 x 10^-4 M crystal viole...

Calculate the concentration of a crystal violet solution prepared by diluting 4.0 mL of 1.0 x 10^-4 M crystal violet with 2.0 mL of 0.100 M NaOH and 4.0 mL of distilled water.    I am so so so... more

A volume of 253 mL of hydrogen is collected over water; the water level in the collecting vessel is the same as the outside level. Atmospheric pressure is 756.0

A 0.548 gram sample of a metal, M, reacts completely with sulfuric acid according to:M(s)+H2SO4(aq) -> MSO4(aq)+H2(g)A volume of 253 mL of hydrogen is collected over water; the water level in... more

What is the boiling point of an aqueous solution that freezes at -5.5 °C?

The equation that was given in class doesn't make sense I need some guidance on how to solve this problem.

Ammonia burns in air as follows: 4NH3(g) + 3O2(g) ? 2N2(g) + 6H2O(g)

I am trying to figure out this question, but I have no idea how. Please help!   Ammonia burns in air as follows: 4NH3(g) + 3O2(g) → 2N2(g) + 6H2O(g), How many liters of N2(g) are formed by... more

Titration question

When a 21.1 mL sample of a 0.403 M aqueous hydrocyanic acid solution is titrated with a 0.420 M aqueous sodium hydroxide solution, what is the pH at the midpoint in the titration

If a wavelength is .089 nanometers, how much energy is it giving off in Joules per mole?

A wavelength of light is 0.089 nm.  How many Joules per mole is it giving off.   I got 3.79 *10-39 J/mol   but I don't think that's right.

Ionic Size

I really don't understand what this is asking... please help.   1.) As you move left to right across the period, there are two elements that instead show a decrease in ionization energy. Identify... more

Perform a rxn to obtain 5 g ethyl bromide. Assuming that a normal percentage yield is 85%, what min quantity of materials needed to give desired product

Density of ethyl bromide is 1.47 g/cm3 Molecular mass of ethyl bromide is 108.97 g/mol   I need the answer in mL ethanol and mL phosphorus tribromide

to 25ml of 023 molar ammonium hydroxide solution 25 ml of 0.25 M HCl is added. What will be the ph of the resulting solution?

i am struggling to figure out to to get ph using the kb value for ammonium hydroxide of 1.8x10^-5. 

determine which experiences a lower effective nuclear charge.

using words and/ or drawings explain why. A) an electron in a 2s or an electron in a 2p B) a valence electron on sulfure or a valence electron on silicon C) a valence electron on chlorine or a... more

For The reaction: A + B ? C + D, the rate law was found by experiment to be: rate=k[B]2. What is the effect of doubling the concentration of B?

The rate would be doubled. The rate would be one quarter as great. The rate would be four times as great. The rate would be unchanged. The rate would be cut in half.

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