A researcher wants to determine the concentration of beta-carotene in carrots. She obtains a 0.554 M stock solution of beta-carotene and creates Dilution A by transferring 23.00 mL of stock solution into a new container and diluting it with solvent to a final volume of 99.00 mL. She creates Dilution B by transferring 59.00 mL of stock solution into a new container and diluting it with solvent to a final volume of 73.00 mL. She creates Dilution C by transferring 8.00 mL of Dilution B into a new container and diluting it with solvent to a final volume of 25.00 mL. She measures the absorbance of each solution and obtains the values below. Plot the data in a spreadsheet software and determine the best-fit line. What is the slope of the best-fit line?   Solution Absorbance Stock solution 0.971 Dilution A 0.273 Dilution B 0.597 Dilution C 0.294

Bud N. Chemist mixes 125.0 mL of 0.0250 M sodium phosphate (aq) with 75.0 mL of 0.0500 M calcium hydroxide (aq), resulting in an observable reaction. (a) Write the balanced total equation and balanced net ionic equation for the reaction.

A researcher wants to determine the concentration of beta-carotene in carrots. She obtains a 0.689 M stock solution of beta-carotene and creates Dilution A by transferring 11.00 mL of stock solution into a new container and diluting it with solvent to a final volume of 91.00 mL. She creates Dilution B by transferring 51.00 mL of stock solution into a new container and diluting it with solvent to a final volume of 99.00 mL. She creates Dilution C by transferring 7.00 mL of Dilution B into a new container and diluting it with solvent to a final volume of 20.00 mL. She measures the absorbance of each solution and obtains the values below. Plot the data in a spreadsheet software and determine the best-fit line. What is the slope of the best-fit line? Report your answer with three places after the decimal. Solution Absorbance Stock solution 0.981 Dilution A 0.229 Dilution B 0.47 Dilution C 0.287

You are asked to create a 0.35 M solution of calcium chloride (CaCl2) using a 250.0 mL volumetric flask. Calculate the mass of CaCl2 needed to make this stock (original) 0.35 M CaCl2 solution.   You are asked to create 50.0 mL of 0.15 M CaCl2 from the stock solution you made in (A). Calculate the volume of stock solution you need to create your diluted solution.   You have two solvents, difluoromethane (CH2F2) and ethanol (C2H5OH) available to dissolve your CaCl2. Which solvent would be more appropriate to use? Justify your response in 2 sentences or less.   You react 30.0 mL of  0.35 M CaCl2 with excess solid lithium. The balanced reaction is shown below. What mass of solid calcium is made during this experiment? CaCl2(aq) +  2 Li(s) → Ca(s) + 2 LiCl(aq)

Timely matter!

A chemist needs to determine the concentration of a sulfuric acid solution by titration with a standard sodium hydroxide solution. He has a 0.1437 M standard sodium hydroxide solution. He takes a 25.00 mL sample of the original acid solution and dilutes it to 250.0 mL. Then, he takes a 10.00 mL sample of the dilute acid solution and titrates it with the standard solution. The endpoint was reached after the addition of 18.80 mL of the standard solution. What is the concentration of the original sulfuric acid solution? concentration: M

Solid potassium phosphate is slowly added to 150 mL of a 0.135 M aluminum chloride solution until the concentration of phosphate ion is 0.0647 M. The mass of aluminum ion remaining in solution is grams.

A 0.430 M solution of KCl needs to be prepared through dilution. A 2.00 M stock solution will be added to a 0.250 L volumetric flask and then water will be added to the 0.250 L mark. Determine the volume (in mL) of the 2.00 M stock solution of KCl needed to produce this solution.

A 25.00-mL sample of a commercial vinegar is diluted with de-ionized water to 100.0 mL. Then, a 10.00-mL portion of the dilute vinegar solution is titrated with 0.1125 M NaOH solution, and the titration requires 18.50 mL of the NaOH solution to neutralize the acetic acid in the dilute vinegar sample. Calculate the molar concentration of acetic acid in the original vinegar sample (before dilution). The acid-base reaction occurs as follows:              HC2H3O2(aq)  +  NaOH(aq)  -->  NaC2H3O2(aq)  +  H2O(g)          (A) 0.8325 M           (B) 0.2081 M           (C) 0.3330 M           (D) 0.2432 M

A 0.500 M solution of KCl needs to be prepared through dilution. A 2.00 M stock solution will be added to a 0.250 L volumetric flask and then water will be added to the 0.250 L mark. Determine the volume (in mL) of the 2.00 M stock solution of KCl needed to produce this solution.