Chemistry Answers

a. A gas occupies a volume of 400 cm3

at a pressure of 2.00 atm.

What would be the new pressure if the volume is increased to 500 cm3 ?

How do you get the volume of HCl and Volume of gas in a flask using a mass HCl of 53.23 g and Density HCl of 1.05 g/mL

What is the oxidation number nitrogen in PB(NO₃)₂

Derive an expression for the entrophy change for isothermal mixing of ideal gas

Chemist to determine copper concentration in rock sample. Knowing copper undergoes redox reactions, they chose to use iodometric titration for analysis. Unknown sample weighing 1.5098g was acidified with 3.0M H2SO4 to dissolve copper compounds and diluted with 30mL distilled water. This was followed by addition of excess KI producing I2 and CuI precipitate from Cu2+(Reaction 1). Then, liberated I2 reacted with excess KI forming triiodide anion(Reaction 2), which was titrated with Na2S2O3 titrant(Reaction 3). This entire solution required 17.60 mL of titrant to reach starch end point.

MW: Cu (63.546)

a. Write balanced chemical equation for Reactions 1-3

b. Write mole ratio between Cu2+ and S2O32–

Prior to titration of sample, titrant was standardized by taking 50.0 mL of 6.7863x10-3M standard KIO3 solution, acidifying, and adding KI crystals. Titration of this solution required 9.80mL to reach starch endpoint.

c. Write concentration of S2O32– titrant in M

d. Write copper content of rock sample in %w/w

why is it that when you try to boil an egg in an open pot, and leave awhile, upon returning you've noticed the water decreases? what about the movement of water molecules? what if you decided to put a lid on the pot, what will be the movement of the water molecules?

What is the weight percent (w/w) of NaOH in a solution prepared by dissolving 30.0g of NaOH in 120.0g of H₂O?

While work‎ing in a metal proc‎essing facility, Letlen had accide‎ntally mixed two me‎tal vats toge‎ther rea‎ting an alloy. On‎e vat ‎was lab‎eled for cadmium, w‎hile the other was not. It can be ass‎umed that he‎se are of pure metal comp‎osition. To identify this metal, Letlen took 1.000 g of the homogenous alloy ample composed of cadmium and the unknown metal, dissolved, and diluted it to exactly 100.0 mL in a volumetric flask. A 20.00-mL aliquot was taken and titrated this using 22.82 mL of 0.05000 M EDTA

MW: Cd (112.411 g/mol)

a. Calcul‎ate the moles of Cd and the m‎oles of unkno‎wn metal in the 20.00‎-mL aliquot.

b. Calc‎ulate the mo‎les of Cd and the mo‎les of unk‎nown metal in the s‎ample.

c. Calc‎ulate the mass (in g) of Cd and the m‎ass (in g) of unk‎nown metal in the sam‎ple.

d. Wh‎at is the MW (in g/mol) of the unkn‎own met‎al?

e. What is the ide‎ntity of the unkno‎wn met‎al that Letlen accid‎entally mix‎ed?