09/29/22

Which best demonstrates the placebo effect?
Which best demonstrates the placebo effect?A. a patient who quits smoking because he thinks he is given antismoking pills but is really given sugar pillsB. a patient who feels better with an... more
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09/29/22

The mass of an evacuated 255 mL flask is 143.187 g . The mass of the flask filled with 356 mbar of an unknown gas at 25 ∘C is 143.348 g . Calculate the molar mass of the unknown gas.

The mass of an evacuated 255 mL flask is 143.187 g . The mass of the flask filled with 356 mbar of an unknown gas at 25 ∘C is 143.348 g . Calculate the molar mass of the unknown gas.
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09/29/22

I need help solving it by the rule of three #Chemistry
Rust contains an iron-oxygen compound in which there are three oxygen atoms for each two iron atoms. In this compound, the iron to oxygen mass ratio is 2.325:1. Another compound of iron and oxygen... more
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09/29/22

Please explain significant figures to me
Hi, so I am taking AP Chem but I'm still iffy on sig figs since my teacher didn't teach it very well last year, and my teacher this year is subtracting points off tests if we have incorrect sig... more
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09/29/22

Calculate the energy change when an electron falls from the n =5 energy level to the n = 1 energy level in a hydrogen atom.
Calculate the energy change when an electron falls from the n =5 energy level to the n = 1 energy level in a hydrogen atom. AE =-2.178 × 10^-18 J( 1/2 n final -1/2 n final)
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09/29/22

The density of liquid bromine is 3.12g/mL. What is the mass of 0.390L of bromine (in g)

The density of liquid bromine is 3.12g/mL. What is the mass of 0.390L of bromine (in g)
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09/29/22

Determine the number of atoms that would make up a 44.9 g sample of Selenium.
Determine the number of atoms that would make up a 44.9 g sample of Selenium.
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09/28/22

Calculate the concentration of C at equilibrium.
Consider the given reaction.A(aq)+B(s)↽−−⇀C(aq) 𝐾=9.40Suppose 10.9 mol A reacts with excess B in 6.45 L of solution. Calculate the concentration of C at equilibrium.
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09/28/22

If a 5.305.30 M sample of A is heated to 500 K, what is the concentration of B at equilibrium?
Consider the reaction.A(aq)↽−−⇀2B(aq) 𝐾=2.03×10-6 at 500 KIf a 5.305.30 M sample of A is heated to 500 K, what is the concentration of B at equilibrium?
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09/28/22

titrations part 2
A 0.5450-g sample of an unknown monoprotic acid is dissolved in water and titrated with standardized sodium hydroxide. The equivalence point in the titration is reached after the addition... more
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09/28/22

titrations part 1
Potassium hydrogen phthalate is a solid, monoprotic acid frequently used in the laboratory as a primary standard. It has the unwieldy formula of KHC8H4O4. This is often written in shorthand... more
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09/28/22

Calculate the equilibrium concentrations of each gas at 430 ∘C.
A mixture of 0.435 M H2,0.435 M H2, 0.357 M I2,0.357 M I2, and 0.874 M HI0.874 M HI is enclosed in a vessel and heated to 430... more
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09/28/22

Calculate the equilibrium pressure of each gas at 700 K.
A mixture of 0.683 atm ClF30.683 atm ClF3 , 0.545 atm F20.545 atm F2 , and 0.427 atm ClF0.427 atm ClF is heated in a closed vessel... more
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09/28/22

Calculate the solubility product, 𝐾spKsp, for SrF2SrF2.
In a saturated aqueous solution of SrF2SrF2, the strontium ion concentration is 8.55×10−48.55×10−4 M and the fluoride ion concentration is 1.71×10−31.71×10−3 M. Calculate the solubility... more
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09/28/22

How do I set up this equilibrium pressure question?
An equilibrium mixture contains N2O4, (P= 0.28 atm ) and NO2 (P= 1.0 atm ) at 350 K. The volume of the container is doubled at constant temperature.Calculate the equilibrium pressure of N2O4 when... more
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09/28/22

What is molar mass?
The freezing point of an aqueous solution containing an unknown solute is -2.60 ∘C. The solution was prepared by dissolving 5.00 g of a nonelectrolytic solute in 100. mL of water. What is the molar... more
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09/28/22

Help! How would I answer the following chemistry questions? Thank you so much!!

a) Determine the molarity and mass percent of a solution in mol/L that is prepared by completely dissolving 3.56g of SrBr2 (molar mass is: 247.428 g/mol). The density of water is 1.00 g/mL.b) A... more
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09/28/22

A 6.00 L tank at 14.7 C is filled with 4.19 g of chlorine pentafluoride gas and 10.1 g of sulfur hexafluoride gas. You can assume both gases behave as ideal gases under these conditions.

Have to find the mole fraction, partial pressure and total pressure. I attempted this problem but it seems like I did something wrong, I'm not sure what though. I first found the mole fractions,... more
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09/27/22

Concentration and Molarity
In the laboratory, a student adds 12.9 g of chromium(II) nitrate to a 250. mL volumetric flask and adds water to the mark on the neck of the flask. Calculate the concentration (in mol/L)... more
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09/27/22

The ideal gas law
What volume of oxygen gas will fill a balloon that is at a pressure of 728 mmHg, at standard temperature?the number of moles oxygen gas is 0.89mol
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09/27/22

Chemistry Question
Ethanol, C2H5OH, is considered clean fuel because it burns in oxygen to produce carbon dioxide and water with few trace pollutants. If 500.0 g of H2O are produced during the combustion of ethanol,... more
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09/27/22

The mol fractions (Xbenzene = 0.25) & (Xtoluene = 0.75) in a solution are given at 25C. The densities at are (ρbenzene = 0.876 g/mL) & (ρtoluene = 0.867 g/mL). What is the molal concentration of both?
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09/27/22

The vapor pressure data for an unknown liquid at 50 °C was 13.3 kPa and at 120 °C was 107 kPa.What is the value of ∆Hvap for this gas?
Chemistry II Question
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09/27/22

F2 (g) + Cl2 (g) = 2 ClF (g) Kc = 272.3
If you put 3.000 M F2 and 3.000 M Cl2 into a container at these conditions and let it go to equilibrium, what are the equilibrium concentrations of F2 and ClF?
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09/26/22

General Chemistry

If you have 214.1 mL of a 1.085 M solution of sodium hydroxide, how many mL of a 0.950 M solution of sulfuric acid do you need in order to neutralize it? _____ mL   
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