Chemistry, 04.05.2021 21:10 zaymuney3063

How much heat is required to raise 250.0 g of ice at a temperature –15.0°C to105.0°C?

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Chemistry, 22.06.2019 00:00, 2024daisjavien

Which actions would increase the rate at salt dissolves in water? stir the water? crush the salt? use less water? heat the water? cool the salt

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Chemistry, 22.06.2019 05:30, MansellS5529

A3.37-mg sample of protein was chemically digested to convert its nitrogen into ammonia and then diluted to 100.0 ml. then 10.0 ml of this solution was placed in a 50-ml volumetric flask and treated with 5 ml of phenol solution plus 2 ml of sodium hypochlorite solution. the sample was diluted to 50.0 ml, and the absorbance at 625 nm was measured in a 1.00-cm cuvette and found to be 0.486. for reference, a standard solution was prepared from 10.0 mg of nh4cl (molar mass = 53.49 grams/mole) dissolved in 1.00 l of water. then 10.0 ml of this standard was placed in a 50-ml volumetric flask, treated in the same manner as the unknown, and the absorbance found to be 0.323. finally, a reagent blank was prepared using distilled water in place of unknown, it was treated in the same manner as the unknown, and the absorbance found to be 0.076. calculate the weight percent of nitrogen in the protein.

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Chemistry, 22.06.2019 19:00, cindyroxana229

Nan element’s square on the periodic table, the number with the greatest numerical value represents the

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Chemistry, 23.06.2019 06:40, 1991987

1.) which of the following is a molecule but not a compound? a. he b. f2 c. h2o d. ch4 2.) what is a physical combination of substances? a. a compound b. a molecule c. a mixture d. an element 3.) what is a chemical combination of substances? a. a compound b. an atom c. a mixture d. an element 4.) what is the relationship between the solute and solvent in a solution? a. they form a compound b. they form a mixture c. they form molecules d. they form chemical bonds 5.) the gases in air dissolve in water. what would be one way to reduce the amount of a gas dissolved in water? a. add more water b. reduce the air pressure c. increase the air pressure d. stir the water 6.) how would you determine the solubility of a substance? a. find how well it dissolved various substances. b. find the mass and the volume of the substance. c. find the temperature at which the substance evaporated. d. find how much i was able to dissolve in a solute. 7.) the periodic table organizes all of the kinds of a. molecules. b. compounds. c. atoms. d. ions. 8.)what distinguishes two substances combined to become a compound vs. two substances combined to become a mixture? a. whether they can be easily separated b. whether they chemically bond together c. whether they both are visible d. whether they are heterogeneous 9.) the principle components of air are: n2 78% o2 21% ar 0.95% co2 0.038% this is a solution of a. molecules and atoms. b. molecules. c. compounds and molecules. d. atoms.